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  • 1.
    Bejarano, Maria D.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    The effects of hydropeaking on riverine plants: a review2018Inngår i: Biological Reviews, ISSN 1464-7931, E-ISSN 1469-185X, Vol. 93, nr 1, s. 658-673Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Hydropeaking refers to frequent, rapid and short-term fluctuations in water flow and water levels downstream and upstream of hydropower stations. Such fluctuations are becoming increasingly common worldwide and are known to have far-reaching effects on riverine vegetation. Novel hydrology caused by hydropeaking has no natural correspondence in freshwater systems, and hence few species have adaptations to all its aspects. Here, we review the literature on hydropeaking effects on riverine plants and define the state of the information on this human alteration of riverine ecosystems. We focus on riparian plants, but also draw on information from aquatic plant species, which exhibit a wide variety of adaptations to inundation and associated processes. Riparian plants face both physiological and physical constraints because of the shifts between submergence and drainage, and erosion of substrates. At the population level, hydropeaking may favour dispersal within, but not between, reservoirs, but may hamper germination, establishment, growth and reproduction. At the community level, strong filtering towards easily dispersed, flexible, flood-tolerant and amphibious plants is expected, although few species share these traits. Hence, most riparian plant species are expected to disappear or be pushed towards the upper boundaries of the regulated river margin. Future research should examine more closely global variation in hydropeaking effects, including other taxonomic groups of species and the diversity of hydropeaking regimes. There is also a need for studies focusing on identifying the boundaries within which hydropeaking could operate without impairing plant life.

  • 2.
    Bejarano, Maria D.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Department of Natural Systems and Resources, Technical University of Madrid, Madrid, Spain.
    Sordo-Ward, Alvaro
    Alonso, Carlos
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Hydropeaking affects germination and establishment of riverbank vegetation2020Inngår i: Ecological Applications, ISSN 1051-0761, E-ISSN 1939-5582, artikkel-id e02076Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hydropeaking, defined as frequent and rapid variation in flow in regulated rivers with hydropower plants over a short period of time, usually sub-daily to weekly, alters hydraulic parameters such as water levels or flow velocity and exerts strong impacts on fluvial ecosystems. We evaluated the effects of hydropeaking on riverbank vegetation, specifically assessing the germination and establishment of seedlings and cuttings of plant species representing a variation in traits. We used seeds and seedlings and cuttings varying in size as phytometers, and transplanted them to riverbanks both above and below dams used for hydropower production in northern Sweden, selected to represent a gradient in hydropeaking intensity, and along a free-flowing reach. We also analyzed sub-daily water-level variables modified by hydropeaking to identify variables key in explaining the observed vegetation patterns. We found that plant responses to hydropeaking varied with species, with flood-intolerant species being the most strongly affected, as early as the germination stage. In contrast, seeds of flood-tolerant species managed to germinate and survive the early establishment phase, although strong erosive processes triggered by hydropeaking eventually caused most of them to fail. The fate of flood-intolerant species identifies germination as the most critical life-history stage. The depth and frequency of the inundation were the leading variables explaining plant responses, while the duration of shallow inundation explained little of the variation. The rise and fall rates of water levels were key in explaining variation in germination success. Based on the results, we propose restoration measures to enhance establishment of riparian plant communities while minimizing the impact on hydropower electricity production. Given the strong decrease in the germination of species intolerant to prolonged flooding with hydropeaking, planting of seedlings, preferably of large sizes, together with restrictions in the operation of the power plant during the establishment phase to enhance survival would be the best restoration option. Given the high probability of plant uprooting with hydropeaking, bank protection measures have the potential to increase riparian plant survival of all species, including flooding-tolerant species.

  • 3.
    Blume-Werry, Gesche
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Milbau, Ann
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Root phenology unresponsive to earlier snowmelt despite advanced aboveground phenology in two subarctic plant communitiesManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Earlier snowmelt at high latitudes advances aboveground plant phenology, thereby affecting water, nutrient and carbon cycles. Despite the key role of fine roots in these ecosystem processes, phenological responses to earlier snowmelt have never been assessed belowground. We experimentally advanced snowmelt in two contrasting plant community types (heath and meadow) in northern Sweden and measured above- and belowground phenology (leaf-out, flowering and fine root growth). We expected earlier snowmelt to advance both above- and belowground phenology, and shrub-dominated heath to be more responsive than meadow. Snow melted on average nine days earlier in the manipulated plots than in controls, and soil temperatures were on average 0.9 °C higher during the snowmelt period of three weeks. This resulted in small advances in aboveground phenology, but contrary to our expectations, root phenology was unresponsive, with root growth generally starting before leaf-out. Both plant community types responded similarly to the snowmelt treatment, despite strong differences in dominating plant functional types, and root properties, such as root length and turnover. The lack of a response in root phenology, despite warmer soil temperatures and aboveground phenological advances, adds evidence that aboveground plant responses might not be directly translated to belowground plant responses, and that our understanding of factors driving belowground phenology is still limited, although of major importance for water, nutrient and carbon cycling.

  • 4.
    Blume-Werry, Gesche
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Milbau, Ann
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Department of Biodiversity and Natural Environment, Research Institute for Nature and Forest INBO, Kliniekstraat 25,1070 Brussels, Belgium.
    Root phenology unresponsive to earlier snowmelt despite advanced above-ground phenology in two subarctic plant communities2017Inngår i: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 31, nr 7, s. 1493-1502Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1. Earlier snowmelt at high latitudes advances above-ground plant phenology, thereby affecting water, nutrient and carbon cycles. Despite the key role of fine roots in these ecosystem processes, phenological responses to earlier snowmelt have never been assessed below-ground. 2. We experimentally advanced snowmelt in two contrasting plant community types (heath and meadow) in northern Sweden and measured above- and below-ground phenology (leaf-out, flowering and fine root growth). We expected earlier snowmelt to advance both above- and below-ground phenology, and shrub-dominated heath to be more responsive than meadow. 3. Snow melted on average 9 days earlier in the manipulated plots than in controls, and soil temperatures were on average 0.9 degrees C higher during the snowmelt period of 3 weeks. This resulted in small advances in above-ground phenology, but contrary to our expectations, root phenology was unresponsive, with root growth generally starting before leaf-out. These responses to the snowmelt treatment were similar in both plant community types, despite strong differences in dominating plant functional types and root properties, such as root length and turnover. 4. The lack of a response in root phenology, despite warmer soil temperatures and above-ground phenological advances, adds evidence that above-ground plant responses might not be directly translated to below-ground plant responses, and that our understanding of factors driving below-ground phenology is still limited, although of major importance for water, nutrient and carbon cycling.

  • 5. Catford, Jane A.
    et al.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Drowned, buried and carried away: effects of plant traits on the distribution of native and alien species in riparian ecosystems2014Inngår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 204, nr 1, s. 19-36Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Riparian vegetation is exposed to stress from inundation and hydraulic disturbance, and is often rich in native and alien plant species. We describe 35 traits that enable plants to cope with riparian conditions. These include traits for tolerating or avoiding anoxia and enabling underwater photosynthesis, traits that confer resistance and resilience to hydraulic disturbance, and attributes that facilitate dispersal, such as floating propagules. This diversity of life-history strategies illustrates that there are many ways of sustaining life in riparian zones, which helps to explain high riparian biodiversity. Using community assembly theory, we examine how adaptations to inundation, disturbance and dispersal shape plant community composition along key environmental gradients, and how human actions have modified communities. Dispersal-related processes seem to explain many patterns, highlighting the influence of regional processes on local species assemblages. Using alien plant invasions like an (uncontrolled) experiment in community assembly, we use an Australian and a global dataset to examine possible causes of high degrees of riparian invasion. We found that high proportions of alien species in the regional species pools have invaded riparian zones, despite not being riparian specialists, and that riparian invaders disperse in more ways, including by water and humans, than species invading other ecosystems.

  • 6.
    Catford, Jane A.
    et al.
    Department of Resource Management and Geography, The University of Melbourne, Australia.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Reducing redundancy in invasion ecology by integrating hypotheses into a single theoretical framework2009Inngår i: Diversity & distributions: A journal of biological invasions and biodiversity, ISSN 1366-9516, E-ISSN 1472-4642, Vol. 15, nr 1, s. 22-40Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aim: Invasion ecology includes many hypotheses. Empirical evidence suggests that most of these can explain the success of some invaders to some degree in some circumstances. If they all are correct, what does this tell us about invasion? We illustrate the major themes in invasion ecology, and provide an overarching framework that helps organize research and foster links among subfields of invasion ecology and ecology more generally.

    Location: Global.

    Methods: We review and synthesize 29 leading hypotheses in plant invasion ecology. Structured around propagule pressure (P), abiotic characteristics (A) and biotic characteristics (B), with the additional influence of humans (H) on P, A and B (hereon PAB), we show how these hypotheses fit into one paradigm. P is based on the size and frequency of introductions, A incorporates ecosystem invasibility based on physical conditions, and B includes the characteristics of invading species (invasiveness), the recipient community and their interactions. Having justified the PAB framework, we propose a way in which invasion research could progress.

    Results: By highlighting the common ground among hypotheses, we show that invasion ecology is encumbered by theoretical redundancy that can be removed through integration. Using both holistic and incremental approaches, we show how the PAB framework can guide research and quantify the relative importance of different invasion mechanisms.

    Main conclusions: If the prime aim is to identify the main cause of invasion success, we contend that a top-down approach that focuses on PAB maximizes research efficiency. This approach identifies the most influential factors first, and subsequently narrows the number of potential causal mechanisms. By viewing invasion as a multifaceted process that can be partitioned into major drivers and broken down into a series of sequential steps, invasion theory can be rigorously tested, understanding improved and effective weed management techniques identified.

    Fulltekst (pdf)
    Catford et al_DD2009
  • 7. Dawson, Michael N.
    et al.
    Algar, Adam C.
    Antonelli, Alexandre
    Dávalos, Liliana M.
    Davis, Edward
    Early, Regan
    Guisan, Antoine
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Lessard, Jean-Philippe
    Marske, Katharine A.
    McGuire, Jenny L.
    Stigall, Alycia L.
    Swenson, Nathan G.
    Zimmermann, Niklaus E.
    Gavin, Daniel G.
    An horizon scan of biogeography2013Inngår i: Frontiers of Biogeography, ISSN 1948-6596, Vol. 5, nr 2, s. 130-157Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The opportunity to reflect broadly on the accomplishments, prospects, and reach of a field may present itself relatively infrequently.  Each biennial meeting of the International Biogeography Society showcases ideas solicited and developed largely during the preceding year, by individuals or teams from across the breadth of the discipline.  Here, we highlight challenges, developments, and opportunities in biogeography that were summarized at or emerge from that biennial synthesis. We note the realized and potential impact of rapid data accumulation in several fields, a Renaissance for inter-disciplinary research, the importance of recognizing the evolution-ecology continuum across spatial and temporal scales and at different taxonomic, phylogenetic and functional levels, and re-exploration of classical assumptions and hypotheses using new tools. However, advances are taxonomically and geographically biased, key theoretical frameworks await development of tools for handling, or strategies for simplifying, the biological complexity seen in empirical systems. Current threats to biodiversity require unprecedented integration of knowledge and development of predictive capacity that may enable biogeography to unite its descriptive and hypothetico-deductive arms and establish a greater role within and outside academia.

    Fulltekst (pdf)
    fulltext
  • 8.
    Dietrich, Anna L.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    A phytometer study evaluating the effects of stream restoration on riparian vegetation2016Inngår i: Ecohydrology, ISSN 1936-0584, E-ISSN 1936-0592, Vol. 9, nr 4, s. 646-658Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Channelization of streams and rivers to facilitate timber floating has cut off riparian zones from the channel, covered them with coarse sediment and resulted in less flooding. Restoration measures aiming to counteract these impacts are expected to create a higher, more natural hydrological variability and enhance site quality for riparian plants. In a long-term field experiment, we evaluated the effect of flooding regime on riparian plant performance by measuring survival and biomass increment of two transplanted phytometer species, a grass (Molinia caerulea) and a forb (Filipendula ulmaria). We also analysed the number and duration of flooding events in channelized and restored stream and river reaches with an indirect method using diurnal temperature oscillation. We found that flow duration was higher, with significantly more flood events at restored compared with channelized sites in medium-sized and large watercourses, particularly during the summer months. Phytometer performance was better at restored sites, and it was positively correlated with duration and frequency of summer flooding, indicating that more but less intense floods after restoration improved site conditions for phytometer growth. This may not only result from an increased heterogeneity in channel morphology caused by the return of boulders but can probably also be attributed to a reduced current velocity at restored sites. Flood variables were more often correlated with other abiotic variables at restored than at channelized sites, which points to an increased land-water connectivity as a result of restoration. 

  • 9.
    Dietrich, Anna L.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Restoration effects on germination and survival of plants in the riparian zone: a phytometer study2015Inngår i: Plant Ecology, ISSN 1385-0237, E-ISSN 1573-5052, Vol. 216, nr 3, s. 465-477Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Many streams that were channelized to facilitate timber floating in northern Sweden, have in recent years been restored by returning coarse sediment (cobbles and boulders) to the channel and reconnecting riparian with instream habitats. We asked if such restoration measures affect germination and survival of plants in the riparian zone, and if such potential effects depend on location in the catchment. We used a paired site approach, comparing the performance of Helianthus annuus (sunflower) phytometers (seeds and seedlings) in the riparian zone in channelized versus restored river reaches along climate and stream size gradients in the Vindel River catchment in northern Sweden. Phytometer survival, substrate availability, and soil nutrient content in large streams were enhanced by restoration, but overall, phytometer performance was negatively related to the length of the growing season, i.e. phytometers grew best at high altitudes and short growing seasons. This result may have been caused by less competition from the shorter and sparser neighbouring vegetation at these sites or to more frequent flooding events, enhancing retention of organic matter. Soil nutrient levels were lowest close to the coast and in large streams, probably due to deposition of mineral sediment. The higher availability of riparian habitat at restored than at channelized sites suggests that plant species richness and abundance may potentially increase after restoration. Seedling transplantation seems to be a preferable revegetation measure, because phytometer seedlings established better than seeds and survival was significantly higher at restored sites. The good plant performance at sites with short growing seasons and high altitudes suggests that, with limited resources, restoration measures should first be located to such sites.

  • 10.
    Dietrich, Anna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Lind, Lovisa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    The Use of Phytometers for Evaluating Restoration Effects on Riparian Soil Fertility2014Inngår i: Journal of Environmental Quality, ISSN 0047-2425, E-ISSN 1537-2537, Vol. 43, nr 6, s. 1916-1925Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ecological restoration of streams in Sweden has become increasingly important to counteract effects of past timber floating. In this study, we focused on the effect on riparian soil properties after returning coarse sediment (cobbles and boulders) to the channel and reconnecting riparian with instream habitats. Restoration increases habitat availability for riparian plants, but its effects on soil quality are unknown. We also analyzed whether the restoration effect differs with variation in climate and stream size. We used standardized plant species to measure the performance of a grass (Phleum pratense L.) and a forb (Centaurea cyanus L.) in soils sampled in the riparian zones of channelized and restored streams and rivers. Furthermore, we analyzed the mass fractions of carbon (C) and nitrogen (N) along with the proportions of the stable isotopes C-13 and N-15 in the soil, as well as its grain size composition. We found a positive effect of restoration on biomass of phytometers grown in riparian soils from small streams, indicating that restoration enhanced the soil properties favoring plant performance. We suggest that changed flooding with more frequent but less severe floods and slower flows, enhancing retention, could explain the observed patterns. This positive effect suggests that it may be advantageous to initiate restoration efforts in small streams, which make up the highest proportion of the stream network in a catchment. Restoration responses in headwater streams may then be transmitted downstream to facilitate recovery of restored larger rivers. If the larger rivers were restored first, a slower reaction would be expected.

  • 11.
    Dietrich, Anna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    A long-term phytometer study to evaluate stream restoration along climate and discharge gradientsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Simplified channel morphology caused by the channelization of rivers to facilitatetimber floating resulted in a less variable flow regime with faster flows in the mainchannel. Restoration measures aiming to counteract these impacts, such as the returnof boulders to the channel and the reconnection of the riparian zone with instreamhabitats, are expected to create a higher, more natural hydrological variability andenhance riparian site quality. In this study, we analysed the number and duration offlooding events at channelized and restored river reaches with an indirect methodusing diurnal temperature oscillation. In a long-term field experiment, we evaluatedthe effect of flooding regime on riparian plant performance by measuring survival andbiomass increment of two transplanted phytometer species, a grass (Molinia caerulea)and a forb (Filipendula ulmaria). We found that flow variability was significantlyhigher at restored compared to channelized sites in medium-sized and large streams,particularly during summer months. Phytometer performance was better at restoredsites and positively correlated with summer flooding, indicating that a more variableflow after restoration improved site conditions for phytometer growth. This may notonly result from the higher heterogeneity in channel morphology caused by thereturned boulders, but can probably also be attributed to a lower flow velocity atrestored sites. Flood variables were more often correlated with other abiotic variablesat restored than at channelized sites, which points to an increased land-waterconnectivity as a result of restoration.

  • 12.
    Dietrich, Anna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Phytometers are underutilised for evaluating ecological restoration2013Inngår i: Basic and Applied Ecology, ISSN 1439-1791, E-ISSN 1618-0089, Vol. 14, nr 5, s. 369-377Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ecological restoration increases, but evaluation of restoration efforts is inadequate because reliable performance indicators are lacking. As plants are important actors in ecological restoration, we suggest that they be used as meters, i.e. phytometers, of restoration success. Phytometer plants are transplanted to different conditions to integrate measures of the prevailing conditions. We analysed 100 studies for the use of phytometers and especially their applicability to evaluate ecological restoration. Most studies employed single species and life-stages and focused on habitat conditions and environmental impacts. Most experiments were conducted on grasslands in wet temperate regions. Growth was the dominant response variable, in long-term studies often combined with reproductive output and plant survival. Only five studies specifically evaluated ecological restoration, implying that its potential is not yet realised. We found phytometers promising in evaluating restoration outcomes given that they are easy to measure, can provide rapid results, and serve as integrative indicators of environmental conditions with the ability of covering many aspects of plant life and ecosystem processes. To evaluate restoration success with high resolution and generality, we suggest a combination of different phytometer species, life-forms and life-stages, and experimental periods >1 year to reduce effects of transplantation and between-year variation and to account for time lags in ecological processes and changes after restoration.

  • 13.
    Dynesius, Mats
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
    Evolutionary consequences of changes in species geographical distributions driven by Milankovitch climate oscillations2000Inngår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 97, s. 9115-9120Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We suggest Milankovitch climate oscillations as a common cause for geographical patterns in species diversity, species' range sizes, polyploidy, and the degree of specialization and dispersability of organisms. Periodical changes in the orbit of the Earth cause climatic changes termed Milankovitch oscillations, leading to large changes in the size and location of species' geographical distributions. We name these recurrent changes ‘‘orbitally forced species' range dynamics'' (ORD). The magnitude of ORD varies in space and time. ORD decreases gradual speciation (attained by gradual changes over many generations), increases range sizes and the proportions of species formed by polyploidy and other ‘‘abrupt'' mechanisms, selects against specialization, and favor dispersability. Large ORD produces species prone neither to extinction nor gradual speciation. ORD increases with latitude. This produces latitudinal patterns, among them the gradient in species diversity and species' range sizes (Rapoport's rule). Differential ORD and its evolutionary consequences call for new conservation strategies on the regional to global scale.

  • 14.
    Dynesius, Mats
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Persistence of within-species lineages: a neglected control of speciation rates2014Inngår i: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 68, nr 4, s. 923-934Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a framework distinguishing three principal controls of speciation rate: rate of splitting, level of persistence, and length of speciation duration. We contend that discussions on diversification become clearer in the light of this framework, because speciation rate variation could be attributed to any of these controls. In particular, we claim that the role of persistence of within-species lineages in controlling speciation rates has been greatly underappreciated. More emphasis on the persistence control would change expectations of the role of several biological traits and environmental factors, because they may drive speciationrate in one direction through the persistence control and in the opposite direction through the other two controls. Traits and environments have been little studied regarding their influence on speciation rate through the persistence control, with climatic fluctuations being a relatively well-studied exception. Considering the recent advances in genomic and phylogenetic analysis, we think that the time is ripe for applying the framework in empirical research. Variation among clades and areas (and thus among traits and environments) in the importance of the three rate controls could be addressed for example by dating splitting events, detecting within-species lineages, and scanning genomes for evidence of divergent selection.

  • 15.
    Dynesius, Mats
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Johansson, Mats E
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Intercontinental similarities in riparian-plant diversity and sensitivity to river regulation2004Inngår i: Ecological Applications, ISSN 1051-0761, E-ISSN 1939-5582, Vol. 14, s. 173-191Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We asked whether assemblages of species with separate evolutionary histories differed in their response to similar human interventions. We assessed this by comparing the response of riparian plant communities to river regulation on two different continents. We compared free-flowing and regulated rivers between boreal parts of North America (Alberta and British Columbia) and Europe (Sweden), using a standardized sampling protocol and the same field staff on both continents. Although the two regions shared few species, both riparian plant-species diversity along free-flowing rivers and the response to different kinds of flow regulation were similar between the continents. The number of riparian-plant species and their amount of cover differed among types of water-level regime, but the continental affiliation of a river-margin site did not statistically explain any of the variation. Within continents, the local flora of the regulated river-margin sites was largely similar in species composition to the free-flowing ones, but the sites along storage reservoirs were more species-poor. The similarity in the response to regulation between the continents suggests that general guidelines for rehabilitation of degraded boreal rivers are a realistic goal. The number of species and genera, plant cover, and species numbers in most trait groups (classified according to growth form and life span) were similar between free-flowing river margins in Europe and North America. Moreover, the regional native species pools of northern Sweden and Alberta were similar in size and composition of species groups, despite the fact that only 27% of the species in Alberta were found in northern Sweden. This is presumably because the floras share a common Tertiary origin and because the regions have had largely similar late-Tertiary and Quaternary histories. The most pronounced difference between the continents was that we found no exotic species on the 183 Swedish river-margin sites, whereas 9% of the species found in all 24 North American plots taken together were exotics. All North American exotics found have occurred in Europe since prehistoric times, and the difference in exotic richness most likely reflects a difference in the number of species humans have transferred from one continent to another, rather than a difference in invasibility between the regions.

    Fulltekst (pdf)
    Dynesius et al_EA2004
  • 16.
    Engström, Johanna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Weber, Christine
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Effects of river ice on riparian vegetation2011Inngår i: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 56, nr 6, s. 1095-1105Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1.  Many rivers and streams experience pronounced ice dynamics caused by the formation of anchor and frazil ice, leading to flooding and disturbance of riparian and aquatic communities.  The effects of dynamic ice conditions on riverine biota are little known.

    2.  We studied the formation of anchor ice in natural streams over 2 years, and assessed the effects of anchor ice on riparian vegetation by comparing sites with frequent or abundant and little or no anchor ice formation. We also studied the direct impact of ice on riparian plants by experimentally creating ice in the riparian zone over three winters, and by exposing plants of different life-forms to ‑18oC cold ice in the laboratory.

    3.  Riparian species richness per 1-m2 plot was higher at sites affected by anchor ice than at sites where anchor ice was absent or rare. Dominance was lower at anchor ice sites, suggesting that ice disturbance enhanced species richness. Species composition was more homogenous among plots at anchor ice sites. Experimentally creating riparian ice corroborated the comparative results, with species richness increasing in ice-treated plots compared to controls, irrespective of whether the sites showed natural anchor ice.

    4.  Because of human alterations of running waters, the natural effects of river ice on stream hydrology, geomorphology and ecology are little known.  Global warming in northern streams will lead to more dynamic ice conditions, offering new challenges for aquatic organisms and river management.  We expect that the results discussed here can stimulate new research, contributing to a better understanding of ecosystem function during winter.

  • 17.
    Engström, Johanna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Effects of stream restoration on dispersal of plant propagules2009Inngår i: Journal of Applied Ecology, ISSN 0021-8901, E-ISSN 1365-2664, Vol. 46, nr 2, s. 397-405Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1. Species immigration is vital for the success of restoring degraded ecosystems, but the effectiveness of enhancing dispersal following restoration is seldom evaluated. Running water is an important vector for plant dispersal. Frequency and duration of floods and channel-network complexity are important factors influencing propagule dispersal. In Sweden, these functions have been modified by channelization to facilitate timber floating, thus hampering emigration and immigration of riparian propagules.

    2. During the last 10–20 years, affected watercourses have been restored by removing barriers and replacing boulders into channels. This is hypothesized to facilitate retention of water-dispersed propagules. We studied the efficiency of propagule retention following restoration by releasing propagule mimics and by placing propagule traps in the riparian zone.

    3. Retention of propagule mimics was highest in sites restored with boulders and large wood. Retention occurred at both high and low flows but was most efficient during low flows when mimics were trapped by boulders and wood. Waterborne propagules ending up at such sites are unlikely to establish unless they can reach the riparian zone later. At high flows, floating propagules are more likely to reach riparian areas suitable for establishment. According to propagule traps placed at various levels of the riparian zone, deposition of plant propagules and sediments did not increase in restored sites.

    4. Synthesis and applications. Our study not only demonstrates that restoration of channel complexity through replacement of boulders and wood can enhance retention of plant propagules, but also it highlights the importance of understanding how restoration effects vary with flow. Most streams are restored to function optimally during median or average flows, whereas communities often are controlled by ecological processes acting during extreme flow events. We advocate that stream restoration should be designed for optimal function during those discharges under which the ecological processes in question are most important, which in this case is, during high flow.

    Fulltekst (pdf)
    Engström et al_JAE2009
  • 18.
    Frainer, André
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Department of Arctic and Marine Biology, University of Tromsø, Tromsø, Norway.
    Polvi, Lina E.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    McKie, Brendan G.
    Enhanced ecosystem functioning following stream restoration: The roles of habitat heterogeneity and invertebrate species traits2018Inngår i: Journal of Applied Ecology, ISSN 0021-8901, E-ISSN 1365-2664, Vol. 55, nr 1, s. 377-385Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1. Habitat restoration is increasingly undertaken in degraded streams and rivers to help improve biodiversity and ecosystem functioning. Follow-up assessments focused on outcomes for biodiversity have often found scant evidence for recovery, raising concerns about the efficacy of habitat restoration for improving ecological integrity. However, responses of other ecological variables, such as ecosystem process rates and the functional trait composition of biological assemblages, have been little evaluated.

    2. We assessed how the restoration of habitat heterogeneity affected multiple functional parameters in 20 boreal stream reaches encompassing both more and less extensively restored sites, as well as channelised and natural reference sites. We further assessed relationships between our functional parameters and a fluvial geomorphic measure of habitat heterogeneity.

    3. Leaf decomposition was positively related to habitat heterogeneity. This was associated with shifts in the functional composition of detritivore assemblages, with the most obligate litter consumers more prominent in reaches showing higher habitat heterogeneity. The deposition of fine particulate organic matter was consistently higher in restored than channelised sites, and was positively related to the heterogeneity gradient. Algal biomass accrual per unit area did not vary either with restoration or the heterogeneity gradient.

    4. Synthesis and applications. Our findings demonstrate that restoration of river habitat heterogeneity can enhance retention and decomposition of organic matter, key ecosystem properties underpinning ecosystem functioning and service delivery. Significantly, enhanced litter decomposition was linked with a change in the functional composition rather than diversity of detritivore assemblages. Future evaluation of the success of habitat restorations should incorporate quantification of ecosystem processes and the functional traits of biota, in addition to measures of fluvial geomorphology and more traditional biotic metrics, to facilitate a more comprehensive and mechanistic assessment of ecological responses.

  • 19.
    Frainer, André
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Polvi, Lina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    McKie, Brendan
    SLU Uppsala.
    Is ecosystem functioning enhanced when habitat complexity increases?: River restoration and the functioning of algal and detrital food websManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Stream restoration is a multi-million dollar business that aims at rehabilitating systems impacted by hydrogeomorphological modifications, such as channelization, and ameliorating physical or ecological degradation caused by catchment-scale impacts, such as agriculture or urbanization. Despite extensive programs aimed at restoring habitat complexity in channelized streams, there is little evidence for a recovery of biological diversity, and functional responses have been little assessed. Notably large-scale habitat restorations have recently been undertaken in a river catchment in northern Sweden, including rehabilitation of large habitat structures (massive boulders, large woody debris) originally removed to facilitate timber floating. Based on a hydrogeomorphological measure of habitat complexity, we characterised variability in habitat complexity across 20 stream reaches in the catchment, including reference, channelised and restored sites. We assessed whether increased habitat complexity following restoration affected retention of organic matter (FPOM), the functional diversity and organisation of the detritivore feeding guild, and two ecosystem processes: algal productivity and litter decomposition. Deposition of FPOM increased along the complexity gradient, as did leaf litter decomposition mediated by invertebrates. The increase in invertebrate-mediated decomposition was associated with shifts in the functional composition of detritivore assemblages, with feeding traits associated with more efficient decomposition more prominent in the restored reaches. There was no change in algal productivity at local scales, but increases in shallow, well- lit habitats favourable for algal growth indicate a possible increase in algal productivity at the stream reach scale. Increases in habitat complexity enhanced functioning within the detritital foodweb at local scales, without any changes in the biodiversity of detritivores. Our findings indicate that aspects of functional diversity and ecosystem functioning may be better than measures of community structure for assessing stream restoration projects.

  • 20.
    Fuentes-Hurtado, Marcelo
    et al.
    Departamento de Ecosistemas y Medio Ambiente, Pontificia Universidad Católica de Chile, Santiago, Chile.
    Hof, Anouschka R.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences (SLU), Umeå, Sweden.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Paleodistribution modeling suggests glacial refugia in Scandinavia and out-of-Tibet range expansion of the Arctic fox2016Inngår i: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 6, nr 1, s. 170-180Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Quaternary glacial cycles have shaped the geographic distributions and evolution of numerous species in the Arctic. Ancient DNA suggests that the Arctic fox went extinct in Europe at the end of the Pleistocene and that Scandinavia was subsequently recolonized from Siberia, indicating inability to track its habitat through space as climate changed. Using ecological niche modeling, we found that climatically suitable conditions for Arctic fox were found in Scandinavia both during the last glacial maximum (LGM) and the mid-Holocene. Our results are supported by fossil occurrences from the last glacial. Furthermore, the model projection for the LGM, validated with fossil records, suggested an approximate distance of 2000 km between suitable Arctic conditions and the Tibetan Plateau well within the dispersal distance of the species, supporting the recently proposed hypothesis of range expansion from an origin on the Tibetan Plateau to the rest of Eurasia. The fact that the Arctic fox disappeared from Scandinavia despite suitable conditions suggests that extant populations may be more sensitive to climate change than previously thought.

    Fulltekst (pdf)
    fulltext
  • 21. Helfield, James M
    et al.
    Capon, Samantha J
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Palm, Daniel
    Restoration of rivers used for timber floating: Effects on riparian plant diversity2007Inngår i: Ecological Applications, ISSN 1051-0761, Vol. 17, nr 3, s. 840-851Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fluvial processes such as flooding and sediment deposition play a crucial role in structuring riparian plant communities. In rivers throughout the world, these processes have been altered by channelization and other anthropogenic stresses. Yet despite increasing awareness of the need to restore natural flow regimes for the preservation of riparian biodiversity, few studies have examined the effects of river restoration on riparian ecosystems. In this study, we examined the effects of restoration in the Ume River system, northern Sweden, where tributaries were channelized to facilitate timber floating in the 19th and early 20th centuries. Restoration at these sites involved the use of heavy machinery to replace instream boulders and remove floatway structures that had previously lined stream banks and cut off secondary channels. We compared riparian plant communities along channelized stream reaches with those along reaches that had been restored 3-10 years prior to observation. Species richness and evenness were significantly increased at restored sites, as were floodplain inundation frequencies. These findings demonstrate how river restoration and associated changes in fluvial disturbance regimes can enhance riparian biodiversity. Given that riparian ecosystems tend to support a disproportionate share of regional species pools, these findings have potentially broad implications for biodiversity conservation at regional or landscape scales.

    Fulltekst (pdf)
    Restoration of rivers used for timber floating: Effects on riparian plant diversity
  • 22.
    Helfield, James M
    et al.
    Department of Environmental Science, Huxley College of the Environment, Western Washington University, Bellingham, Washington 98225-9181 USA.
    Engström, Johanna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Michel, James T
    Department of Environmental Science, Huxley College of the Environment, Western Washington University, Bellingham, Washington 98225-9181 USA.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Effects of river restoration on riparian biodiversity in secondary channels of the Pite River, Sweden2012Inngår i: Environmental Management, ISSN 0364-152X, E-ISSN 1432-1009, Vol. 49, nr 1, s. 130-141Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Between 1850 and 1970, rivers throughout Sweden were channelized to facilitate timber floating.  Floatway structures were installed to streamline banks and disconnect flow to secondary channels, resulting in simplified channel morphologies and more homogenous flow regimes.  In recent years, local authorities have begun to restore channelized rivers.  In this study, we examined the effects of restoration on riparian plant communities at previously disconnected secondary channels of the Pite River.  We detected no increase in riparian diversity at restored sites relative to unrestored (i.e., disconnected) sites, but we did observe significant differences in species composition of both vascular plant and bryophyte communities.  At disconnected sites, plots closest to the stream featured greater representation of mesic-hydric floodplain species, whereas plots farthest from the stream featured greater representation of mesic-xeric species characteristic of the surrounding upland forest.  In contrast, restored sites were most strongly represented by upland species at all distances relative to the stream.  These patterns suggest that restoration has resulted in increased water levels in reconnected channels, but that the restored fluvial regime has not influenced the development of characteristic flood-adapted plant communities.  This may be due to the short time interval (ca. 5 years) since restoration.  Previous studies have demonstrated relatively quick responses to similar restoration in single-channel tributaries, but secondary channels may respond differently due to the more buffered hydrologic regimes typically seen in anabranching systems.  These findings illustrate how restoration outcomes can vary according to hydrologic, climatic and ecological factors, reinforcing the need for site-specific restoration strategies.

  • 23.
    Hof, Anouschka R.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Future Climate Change Will Favour Non-Specialist Mammals in the (Sub)Arctics2012Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, nr 12, s. e52574-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Arctic and subarctic (i.e., [sub] arctic) ecosystems are predicted to be particularly susceptible to climate change. The area of tundra is expected to decrease and temperate climates will extend further north, affecting species inhabiting northern environments. Consequently, species at high latitudes should be especially susceptible to climate change, likely experiencing significant range contractions. Contrary to these expectations, our modelling of species distributions suggests that predicted climate change up to 2080 will favour most mammals presently inhabiting (sub) arctic Europe. Assuming full dispersal ability, most species will benefit from climate change, except for a few cold-climate specialists. However, most resident species will contract their ranges if they are not able to track their climatic niches, but no species is predicted to go extinct. If climate would change far beyond current predictions, however, species might disappear. The reason for the relative stability of mammalian presence might be that arctic regions have experienced large climatic shifts in the past, filtering out sensitive and range-restricted taxa. We also provide evidence that for most (sub) arctic mammals it is not climate change per se that will threaten them, but possible constraints on their dispersal ability and changes in community composition. Such impacts of future changes in species communities should receive more attention in literature.

    Fulltekst (pdf)
    Future Climate Change Will Favour Non-Specialist Mammals in the (Sub)Arctics
  • 24.
    Hof, Anouschka R
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Future of biodiversity in the Barents Region2015Bok (Annet vitenskapelig)
    Abstract [en]

    Climate change may affect biodiversity to a large extent. Its effects have already caused shifts in species distributions and even species extinctions. Since especially high latitude regions are expected to be affected, this publication assesses the impact of future climate change on the biodiversity in the Barents Region (northern parts of Norway, Sweden and Finland, and Northwest Russia). It reports on the impact of climate change on a large range of species, including amphibians, butterflies, birds, mammals, moths, plants, slugs, snails, and reptiles, of which a few were studied more in depth. It further identifies future hotspots of species diversity and gives recommendations on species that should be prioritized for conservation and on areas that should be included in the network of protected areas in future. Lastly, it provides guidance on which aspects require further study.

  • 25.
    Hof, Anouschka R
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    How biotic interactions may alter future predictions of species distributions: future threats to the persistence of the arctic fox in Fennoscandia2012Inngår i: Diversity & distributions: A journal of biological invasions and biodiversity, ISSN 1366-9516, E-ISSN 1472-4642, Vol. 18, nr 6, s. 554-562Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aim With climate change, reliable predictions of future species geographic distributions are becoming increasingly important for the design of appropriate conservation measures. Species distribution models (SDMs) are widely used to predict geographic range shifts in response to climate change. However, because species communities are likely to change with the climate, accounting for biotic interactions is imperative. A shortcoming of introducing biotic interactions in SDMs is the assumption that biotic interactions remain the same under changing climatic factors, which is disputable. We explore the performance of SDMs while including biotic interactions.

    Location Fennoscandia, Europe.

    Methods We investigate the appropriateness of the inclusion of biotic factors (predator pressure and prey availability) in assessing the future distribution of the arctic fox (Alopex lagopus) in Fennoscandia by means of SDM, using the algorithm MaxEnt.

    Results Our results show that the inclusion of biotic interactions enhanced the accuracy of SDMs to predict the current arctic fox distribution, and we argue that the accuracy of future predictions might also be enhanced. While the range of the arctic fox is predicted to have decreased by 43% in 2080 because of temperature-related variables, projected increases in predator pressure and reduced prey availability are predicted to constrain the potential future geographic range of the arctic fox in Fennoscandia 13% more.

    Main conclusions The results indicate that, provided one has a good knowledge of past changes and a clear understanding of interactions in the community involved, the inclusion of biotic interactions in modelling future geographic ranges of species increases the predictive power of such models. This likely has far-reaching impacts upon the design and implementation of possible conservation and management plans. Control of competing predators and supplementary feeding are suggested as necessary management actions to preserve the Fennoscandian arctic fox population in the face of climate change.

  • 26.
    Hof, Anouschka R
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    The usefulness of elevation as a predictor variable in species distribution modelling2012Inngår i: Ecological Modelling, ISSN 0304-3800, E-ISSN 1872-7026, Vol. 246, s. 86-90Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Species distribution models (SDMs) are increasingly used to forecast impacts of climate change on species geographic distributions, but the reliability of predictions is scrutinized. The main limitation of SDMs lies in their assumption that species' ranges are determined mostly by climate, which is arguable. For instance, biotic interactions, habitat and elevation may affect species ranges. The inclusion of habitat-related variables as predictors in SDMs is generally accepted, but there is no consensus regarding the inclusion of elevation. A review of randomly chosen literature revealed that elevation is used as a predictor variable by just over half of the papers studied with no apparent trends as to why, except that papers predicting mammal species distributions for large regions included elevation more often than not, and that papers that predicted mammal ranges for small regions tended to exclude elevation. In addition, we compared the performance of SDMs with and without elevation as a predictor variable for the distribution of north European mammals and plants and found that the difference between their performances is statistically significant for mammals, slightly favouring exclusion of elevation. No differences were found for plants.

    (C) 2012 Elsevier B.V. All rights reserved.

  • 27.
    Hof, Anouschka R.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, Wisconsin 53706 USA.
    Rodriguez-Castaneda, Genoveva
    Allen, Andrew M.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Vulnerability of Subarctic and Arctic breeding birds2017Inngår i: Ecological Applications, ISSN 1051-0761, E-ISSN 1939-5582, Vol. 27, nr 1, s. 219-234Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recent research predicts that future climate change will result in substantial biodiversity loss associated with loss of habitat for species. However, the magnitude of the anticipated biodiversity impacts are less well known. Studies of species vulnerability to climate change through species distribution models are often limited to assessing the extent of species' exposure to the consequences of climate change to their local environment, neglecting species sensitivity to global change. The likelihood that species or populations will decline or go extinct due to climate change also depends on the general sensitivity and adaptive capacity of species. Hence, analyses should also obtain more accurate assessments of their vulnerability. We-addressed this by constructing a vulnerability matrix for 180 bird species currently breeding in Subarctic and Arctic Europe that integrates a climatic exposure-based vulnerability index and a natural-history trait-based vulnerability index. Species that may need extra conservation-attention based on our matrix include the Great Snipe (Gallinago media), the Rough-legged Buzzard (Buteo lagopus), the Red-throated Pipit (Anthus cervinus), the Common Swift (Apus apus), the Horned Lark (Eremophila alpestris), and the Bar-tailed Godwit (Limosa lapponica). Our vulnerability matrix stresses the importance of looking beyond exposure to climate change when species conservation is the aim. For the species that scored high in our matrix the future in the region looks grim and targeted conservation actions, incorporating macroecological and global perspectives, may be needed to alleviate severe population declines. We further demonstrate that climate change is predicted to significantly reduce the current breeding range of species adapted to cold climates in Subarctic and Arctic Europe. The number of incubation days and whether the species was a habitat specialist or not were also among the variables most strongly related to predicted contraction or expansion of species' breeding ranges. This-approach may aid the identification of vulnerable bird species worldwide.

  • 28.
    Jansson, R
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
    Backx, H
    Boulton, A J
    Dixon, M
    Dudgeon, D
    Hughes, Nakamura
    Stanley, E
    Tockner, K
    Stating mechanisms and refining criteria for ecologically successful river restoration: A comment on Palmer et al. (2005)2005Inngår i: Journal of Applied Ecology, Vol. 42, s. 218-222Artikkel i tidsskrift (Fagfellevurdert)
  • 29.
    Jansson, R
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Zinko, U
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Merritt, D M
    Nilsson, C
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Hydrochory increases riparian plant species richness: a comparison between a free-flowing and a regulated river2005Inngår i: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 93, s. 1094-1103Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]
    • 1The importance of dispersal for plant community structure is poorly understood. Previous studies have hypothesized that patterns in the distribution and genetic structure of riparian plant communities were caused by hydrochory, i.e. plant dispersal by water. We separated the relative contributions of propagules from hydrochory and other dispersal vectors by comparing colonization in pairs of plots, one subject to flooding and deposition of hydrochores and the other unflooded.
    • 2The number of colonizing individuals and the mortality rate of individuals per year did not differ significantly with flooding, but hydrochory increased the number of colonizing species per year and plot by 40–200%. The pool of colonizing species was 36–58% larger per year for flooded than for unflooded plots, indicating that hydrochory increased the diversity by facilitating long-distance dispersal. Hydrochory resulted in more diverse plant communities after 3 years of succession at both plot and reach scales, despite the fact that flooding caused plant mortality.
    • 3We found no evidence that dams reduce the abundance and diversity of water-dispersed propagules by acting as barriers for plant dispersal. The role of hydrochory for plant colonization was similar between a free-flowing and a regulated river, although in fragmented rivers propagule sources are likely to be more local (within-impoundment).
    • 4We conclude that plant dispersal by water, as well as fluvial disturbance, is important for enhancing species richness in riparian plant communities. As flowing water may carry buoyant seeds long distances, riparian plant communities may receive a comparatively large proportion of their seeds by long-distance dispersal.
  • 30.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
    Extinction risks from climate change: macroecological and historical insights2009Inngår i: F1000 Biology Reports , ISSN 1740-4118, Vol. 1, s. 44-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Human-induced climate change may threaten a large proportion of Earth's biota, but the uncertainties involved in projecting the future geographical distributions of species make quantitative predictions of extinction risk difficult to make. I discuss how insight from recent advances in macroecology and knowledge about species responses to past climate change can help predict extinction risks more accurately.

  • 31.
    Jansson, Roland
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
    Davies, T. J.
    Global variation in diversification rates of flowering plants: Energy vs. climate change2008Inngår i: Ecology Letters 2008, Vol. 11, s. 173–183-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We used the largest DNA-based phylogeny of flowering plants to date to evaluate the importance of energy vs. past climate change in predicting global patterns in diversification. Relative diversification rates increased towards the equator, suggesting that differences in per-lineage net diversification may be an important component of the latitudinal diversity gradient. The amplitude of Quaternary climate oscillations experienced by families explained variation in diversification equally well compared to contemporary energy measures, and energy and climate change measures were intercorrelated, making it difficult to reject either as a causal mechanism. Many putative mechanisms linking diversification to energy availability do not apply to plants, whereas the climate change mechanism has more support. We also present the first global map of angiosperm diversification, showing that, after correcting for family range-size, tropical diversification rates were fastest for clades currently in regions with high endemic species richness outside the main lowland rainforest areas.

  • 32.
    Jansson, Roland
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
    Dynesius, Mats
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
    The fate of clades in a world of recurrent climatic change - Milankovitch oscillations and evolution2002Inngår i: Annual Review of Ecology and Systematics, ISSN 0066-4162, E-ISSN 2330-1902, Vol. 33, s. 741-778Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Variations in Earth's orbit with periods of 10-100 thousand years (kyr) (Milankovitch oscillations) have led to recurrent and rapid climatic shifts throughout Earth's history. These cause changes in the geographical distributions of clades, which we term orbitally forced range dynamics (ORD). The magnitude of ORD varies geographically, e.g., with latitude. Climatic shifts cause extinction, splitting, and merging of gene pools and clades. They select among individuals and clades for traits enhancing the ability to survive in situ and to establish new populations. There is also nonadaptive sorting caused by the large geographical variation in ORD, as only gene pools that are in the right place when climate shifts survive. ORD lead to sorting at many levels of genealogic inclusiveness. Clades that have survived climatic shifts during at least one entire period of the longest significant Milankovitch oscillations (100 kyr), we name β-clades. The products of more recent cladogenesis are α-clades, which are always nested within a β-clade. We conclude that ORD may promote α-clade formation but curb rates of β-clade formation. In areas with little ORD, where gene pools persist without going extinct or merging, clade splits and divergence may accumulate leading to high rates of β-clade formation and β-anagenesis (evolutionary change persisting >100 kyr). High ORD should lead to low numbers of β-clades, β-clades with low levels of spatial genetic divergence, little geographical subdivision and large ranges, organisms with high vagility and low specialization, high proportions of β-clades formed by polyploidization, and little β-anagenesis. We predict global and interregional geographic patterns in these variables caused by differential ORD. Thus, ORD potentially explains a wide array of patterns, suggesting ORD as a fundamental factor in evolution. The vulnerability of biotas to many human activities should vary with the magnitude of ORD.

  • 33.
    Jansson, Roland
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
    Laudon, Hjalmar
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
    Johansson, Eva
    Augspurger, Clemens
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
    The importance of groundwater discharge for plant species number in riparian zones2007Inngår i: Ecology, Vol. 88, nr 1, s. 131–139-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Riparian zones are hotspots of plant species richness in temperate and boreal biomes. The phenomenon is believed to be caused primarily by river-related processes, and upland influences on riparian zones have received relatively little attention. We investigated the importance of discharge of groundwater derived from uplands on riparian patterns in vascular plant species composition. We found that groundwater discharge areas in riparian zones were 36–209% more species rich than non-discharge areas, depending on spatial scale (1–50 m wide transects from annual high-water levels to summer low-water levels) and river (one free-flowing and one regulated). Higher nitrogen availability and less drought stress during low river stages are suggested as the major causes for the higher species diversity in discharge areas. Riparian zones lacking groundwater discharge lost more species following water-level regulation than did discharge areas. This indicates that groundwater discharge areas are more resistant to regulation because both individual plants and plant populations may grow larger in discharge areas. These results demonstrate that riparian zones are controlled by water and nutrient input from upland parts of catchments in ways that have been overlooked despite more than three decades of research into linkages between stream ecosystems and their valleys.

  • 34.
    Jansson, Roland
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Department of Applied Science, Mittuniversitetet Härnösand.
    Dynesius, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Andersson, Elisabet
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Effects of river regulation on river-margin vegetation: a comparison of eight boreal rivers2000Inngår i: Ecological Applications, ISSN 1051-0761, E-ISSN 1939-5582, Vol. 10, nr 1, s. 203-224Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Regulation and fragmentation by dams belong to the most widespread deliberate impacts of humans on the world's rivers, especially in the Northern Hemisphere. We evaluated the effects of hydroelectric development by comparing the flora of vascular plants in 200-m-long reaches of river margin distributed along eight entire rivers in northern Sweden. Four of these rivers were free-flowing, and four were strongly regulated for hydroelectric purposes. First, we compared species diversity per site between entire free-flowing and regulated rivers. To reduce the effects of natural, between-river variation, we compared adjacent rivers. One regulated river had lower plant species richness and cover than two adjacent free-flowing ones, whereas two other parallel rivers, one regulated and another free-flowing, did not differ significantly. Second, river-margin vegetation responded differently to different types of regulated water-level regimes. Both along run-of-river impoundments, with small but daily water-level fluctuations, and along storage reservoirs, with large fluctuations between low water levels in spring and high levels in late summer and fall, the number of species and their cover per site were lower than along the free-flowing rivers. Regulated but unimpounded reaches were most similar to free-flowing rivers, having lower plant cover per site, but similar numbers of species. For reaches with reduced discharge, evidence was mixed; some variables were lower compared to free-flowing rivers whereas others were not. However, for the last two types of regulation, statistical power was low due to small sample sizes. Third, we classified all plant species according to their dispersal mechanisms and tested whether they respond differently to different types of regulated water-level regimes. Three out of four types of regulation had higher proportions of wind-dispersed species, and two out of four had lower proportions of species without specific mechanisms for dispersal, compared to free-flowing rivers, suggesting that dispersal ability is critical for persistence following regulation. Run-of-river impoundments had higher proportions of long-floating species and species with mechanisms for vegetative dispersal, suggesting that water dispersal may still be important despite fragmentation by dams. Fourth, plant species richness and cover varied with both local factors, such as water-level regime, and regional factors, such as length of the growing season. Presence of clay and silt in the river-margin soil, preregulation position of the contemporary river margin, non-reservoir sites, low altitudes, and long growing seasons were associated with high plant species richness and cover.

    Fulltekst (pdf)
    Effects of river regulation on river-margin vegetation: a comparison of eight boreal rivers
  • 35.
    Jansson, Roland
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Keskitalo, E Carina H
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för geografi och ekonomisk historia.
    Vlasova, Tatiana
    Sutinen, Marja-Liisa
    Moen, Jon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Chapin, F Stuart, III
    Bråthen, Kari Anne
    Cabeza, Mar
    Callaghan, Terry V
    van Oort, Bob
    Dannevig, Halvor
    Bay-larsen, Ingrid A
    Ims, Rolf A
    Aspholm, Paul Eric
    Future changes in the supply of goods and services from natural ecosystems: prospects for the European north2015Inngår i: Ecology & society, ISSN 1708-3087, E-ISSN 1708-3087, Vol. 20, nr 3, artikkel-id 32Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Humans depend on services provided by ecosystems, and how services are affected by climate change is increasingly studied. Few studies, however, address changes likely to affect services from seminatural ecosystems. We analyzed ecosystem goods and services in natural and seminatural systems, specifically how they are expected to change as a result of projected climate change during the 21st century. We selected terrestrial and freshwater systems in northernmost Europe, where climate is anticipated to change more than the global average, and identified likely changes in ecosystem services and their societal consequences. We did this by assembling experts from ecology, social science, and cultural geography in workshops, and we also performed a literature review. Results show that most ecosystem services are affected by multiple factors, often acting in opposite directions. Out of 14 services considered, 8 are expected to increase or remain relatively unchanged in supply, and 6 are expected to decrease. Although we do not predict collapse or disappearance of any of the investigated services, the effects of climate change in conjunction with potential economical and societal changes may exceed the adaptive capacity of societies. This may result in societal reorganization and changes in ways that ecosystems are used. Significant uncertainties and knowledge gaps in the forecast make specific conclusions about societal responses to safeguard human well-being questionable. Adapting to changes in ecosystem services will therefore require consideration of uncertainties and complexities in both social and ecological responses. The scenarios presented here provide a framework for future studies exploring such issues.

    Fulltekst (pdf)
    fulltext
  • 36.
    Jansson, Roland
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Malmqvist, Björn
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Restoring freshwater ecosystems in riverine landscapes: the roles of connectivity and recovery processes2007Inngår i: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 52, nr 4, s. 589-596Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1. This paper introduces key messages from a number of papers emanating from the Second International Symposium on Riverine Landscapes held in August 2004 in Sweden, focusing on river restoration. Together these papers provide an overview of the science of river restoration, and point out future research needs.

    2. Restoration tests the feasibility of recreating complex ecosystems from more simple and degraded states, thereby presenting a major challenge to ecological science. Therefore, close cooperation between practitioners and scientists would be beneficial, but most river restoration projects are currently performed with little or no scientific involvement.

    3. Key messages emanating from this series of papers are: The scope, i.e. the maximum and minimum spatial extent and temporal duration of habitat use, of species targeted for restoration should be acknowledged, so that all relevant stages in their life cycles are considered. Species that have been lost from a stream cannot be assumed to recolonise spontaneously, calling for strategies to ensure the return of target species to be integrated into projects. Possible effects of invasive exotic species also need to be incorporated into project plans, either to minimise the impact of exotics, or to modify the expected outcome of restoration in cases where extirpation of exotics is impractical.

    4. Restoration of important ecological processes often implies improving connectivity of the stream. For example, longitudinal and lateral connectivity can be enhanced by restoring fluvial dynamics on flood-suppressed rivers and by increasing water availability in rivers subject to water diversion or withdrawal, thereby increasing habitat and species diversity. Restoring links between surface and ground water flow enhances vertical connectivity and communities associated with the hyporheic zone.

    5. Future restoration schemes should consider where in the catchment to locate projects to make restoration most effective, consider the cumulative effects of many small projects, and evaluate the potential to restore ecosystem processes under highly constrained conditions such as in urban areas. Moreover, restoration projects should be properly monitored to assess whether restoration has been successful, thus enabling adaptive management and learning for the future from both successful and unsuccessful restorations.

  • 37.
    Jansson, Roland
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Rodriguez-Castaneda, Genoveva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Harding, Larisa E.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    What can multiple phylogenies say about the latitudinal diversity gradient?: a new look at the tropical conservatism, out of the tropics, and diversification rate hypotheses2013Inngår i: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 67, nr 6, s. 1741-1755Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We reviewed published phylogenies and selected 111 phylogenetic studies representing mammals, birds, insects, and flowering plants. We then mapped the latitudinal range of all taxa to test the relative importance of the tropical conservatism, out of the tropics, and diversification rate hypotheses in generating latitudinal diversity gradients. Most clades originated in the tropics, with diversity peaking in the zone of origin. Transitions of lineages between latitudinal zones occurred at 16-22% of the tree nodes. The most common type of transition was range expansions of tropical lineages to encompass also temperate latitudes. Thus, adaptation to new climatic conditions may not represent a major obstacle for many clades. These results contradict predictions of the tropical conservatism hypothesis (i.e., few clades colonizing extratropical latitudes), but support the out-of-the-tropics model (i.e., tropical originations and subsequent latitudinal range expansions). Our results suggest no difference in diversification between tropical and temperate sister lineages; thus, diversity of tropical clades was not explained by higher diversification rates in this zone. Moreover, lineages with latitudinal stasis diversified more compared to sister lineages entering a new latitudinal zone. This preserved preexisting diversity differences between latitudinal zones and can be considered a new mechanism for why diversity tends to peak in the zone of origin.

  • 38.
    Jansson, Roland
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Ström, Lotta
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Smaller future floods imply less habitat for riparian plants along a boreal river2019Inngår i: Ecological Applications, ISSN 1051-0761, E-ISSN 1939-5582, Vol. 29, nr 8, artikkel-id e01977Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Climate-change projections suggest large changes in riverine flow regime, which will likely alter riparian communities. In northern Europe, forecasts propose lower annual spring flood peaks and higher winter flows, resulting in narrower riparian zones. To estimate the impact of climate change on habitat extent of riparian plants, we developed a framework estimating the sensitivity and exposure of individual species to streamflow change, and surveyed five reaches along the free-flowing Vindel River in northern Sweden. We modeled the hydrologic niche of riparian plant species based on the probability of occurrence along gradients of flood frequency and duration and used predicted future water-level fluctuations (based on climate models and IPCC emission scenarios) to calculate changes in flow-related habitat availability of individual species. Despite projected increases in runoff, we predict most species to decrease in riparian elevational extent by on average 12-29% until the end of the century, depending on scenario. Species growing in the upper, spring-flood-controlled part of the riparian zone will likely lose most habitat, with the largest reductions in species with narrow ranges of inundation duration tolerance (decreases of up to 54%). In contrast, the elevational extent of most amphibious species is predicted to increase, but conditions creating isoetid vegetation will become rarer or disappear: isoetid vegetation is presently found in areas where ice formed in the fall settles on the riverbank during the winter as water levels subside. Higher winter flows will make these conditions rare. We argue that our framework is useful to project the effects of hydrologic change caused by climate change as well as other stressors such as flow regulation also in other regions. With few rivers remaining unaffected by dams and other human stressors, these results call for monitoring to detect species declines. Management to alleviate species losses might include mitigation of habitat degradation from land-use activities, more environmentally friendly flow schemes, and more intensive management options such as mowing riparian meadows no longer regularly maintained by recurrent floods.

  • 39.
    Karlsson Tiselius, Andreas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Lundbäck, Sofi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Lönnell, Niklas
    Artdatabanken, Sverige Lantbruksuniversitet, Uppsala.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Dynesius, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Bryophyte community assembly on young land uplift islands: dispersal and habitat filtering assessed using species traits2019Inngår i: Journal of Biogeography, ISSN 0305-0270, E-ISSN 1365-2699, Vol. 46, nr 10, s. 2188-2202Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aim: To assess habitat filtering and dispersal limitation in spore plant community assembly using bryophytes on recently emerged land uplift islands as study system. Location Gulf of Bothnia, northern Europe. Taxa Bryophytes, including the spore plant phyla Bryophyta (mosses) and Marchantiophyta (liverworts).

    Methods: The species compositions of 20 coastal land uplift islands differing in age, area, connectivity and habitat composition were recorded in the field. In addition, we compiled a list of the regional species pool (446 species) and gathered data on species traits related to habitat affiliations (substrate, light, moisture, and pH) and dispersal capacity (regional abundance, spore size, sporophyte frequency, sexual system, vegetative propagules). For the 420 species with available trait data, we used multivariate generalized linear models to compare trait effects on species occurrence probabilities on the islands.

    Results: Occurrence probabilities depended strongly on habitat affiliations. In addition, occurrence probabilities were lower for predominantly asexual species than for sexual species and for regionally rare than for regionally abundant species. Having specialized asexual propagules increased occurrence probabilities, but compensated only partly for the reductions in asexual species. No effect of the size of sexually produced spores was detected. Comparison of trait effects across island size and connectivity gradients revealed (a) reduced habitat filtering on larger islands and (b) decreasing negative effects of being predominantly asexual with increasing island connectivity.

    Conclusions: Both habitat filtering and dispersal capacities affect the community assembly of spore plants on land uplift islands. Asexual mosses and liverworts show landscape scale (<= 10 km) dispersal limitation. The weak or absent relationships between island connectivity and the effects of dispersal traits suggest that colonization is regulated mainly by habitat availability and the abundance of each species in a "regional spore rain" from which colonists are recruited.

  • 40.
    Kuglerova, Lenka
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Department of Forest and ConservationSciences, University of British Columbia,Vancouver, Canada.
    Botkova, Kamila
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Responses of riparian plants to habitat changes following restoration of channelized streams2017Inngår i: Ecohydrology, ISSN 1936-0584, E-ISSN 1936-0592, Vol. 10, nr 1, artikkel-id e1798Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ecological effects of stream restoration were evaluated by comparing riparian vegetation, flooding, and habitat properties between channelized and two types of restored streams in northern Sweden. Channelized streams were straightened and cleared of in-stream boulders and wood >50 years ago to facilitate timber floating. Basic restoration (performed 8-10 years ago) returned cleared material back to the channels, and enhanced restoration (3 years ago) added large structural elements (boulders and downed trees) to previously basic-restored streams. Riparian inundation duration increased only after enhanced restoration. Similarly, enhanced-restored reaches had the highest amount of substrate available for plant establishment compared to channelized and basic-restored streams. In contrast, soil biochemical properties (pH and C:N ratio) did not improve following either restoration effort. Riparian plant cover was higher at both restored types than channelized reaches. Plant species richness was higher at plot-scale level (0.25 m(2)) at both restored types in the most species-rich elevation levels compared to channelized reaches, whereas at the reach-scale (>700 m(2) of riparian area), species richness did not differ among stream types. Similarly, species composition segregated between channelized and restored reaches only at the plot scale. We found no significant differences in riparian vegetation between the two restored types. The lack of positive responses of vegetation to enhanced restoration and to variables that changed immediately after restoration (inundation, habitat area) implies that responses were either slower than expected or the changes in hydrology and substrate availability were not as important for riparian flora as believed.

  • 41.
    Kuglerova, Lenka
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Ågren, Anneli
    Laudon, Hjalmar
    Malm-Renöfält, Birgitta
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Groundwater discharge creates hotspots of riparian plant species richness in a boreal forest stream network2014Inngår i: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 95, nr 3, s. 715-725Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Riparian vegetation research has traditionally focused on channel-related processes because riparian areas are situated on the edge of aquatic ecosystems and are therefore greatly affected by the flow regime of streams and rivers. However, due to their low topographic position in the landscape, riparian areas receive significant inputs of water and nutrients from uplands. These inputs may be important for riparian vegetation, but their role for riparian plant diversity is poorly known. We studied the relationship between the influx of groundwater (GW) from upland areas and riparian plant diversity and composition along a stream size gradient, ranging from small basins lacking permanent streams to a seventh-order river in northern Sweden. We selected riparian sites with and without GW discharge using a hydrological model describing GW flow accumulation to test the hypothesis that riparian sites with GW discharge harbor plant communities with higher species richness. We further investigated several environmental factors to detect habitat differences between sites differing in GW discharge conditions. Vascular plant species richness was between 15% and 20% higher, depending on the spatial scale sampled, at riparian sites with GW discharge in comparison to non-discharge sites, a pattern that was consistent across all stream sizes. The elevated species richness was best explained by higher soil pH and higher nitrogen availability (manifested as lower soil C/N ratio), conditions which were positively correlated with GW discharge. Base cations and possibly nitrogen transported by groundwater may therefore act as a terrestrial subsidy of riparian vegetation. The stable isotopes N-15 and C-13 were depleted in soils from GW discharge compared to non-discharge sites, suggesting that GW inputs might also affect nitrogen and carbon dynamics in riparian soils. Despite the fact that many flows of water and nutrients reaching streams are filtered through riparian zones, the importance of these flows for riparian vegetation has not been appreciated. Our results demonstrated strong relationships between GW discharge, plant species richness and environmental conditions across the entire stream size gradient, suggesting that both river hydrology and upland inputs should be considered to fully understand riparian vegetation dynamics.

    Fulltekst (pdf)
    fulltext
  • 42.
    Kuglerová, Lenka
    et al.
    Department of Forest Ecology and Management, Swedish University of Agricultural Science, Umeå, Sweden; Department of Forest and Conservation Sciences, Forest Science Centre, University of British Columbia, Vancouver, British Columbia, Canada .
    Dynesius, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Laudon, Hjalmar
    Department of Forest Ecology and Management, Swedish University of Agricultural Science, Umeå, Sweden.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Relationships between plant assemblages and water flow across a boreal forest landscape: a comparison of liverworts, mosses, and vascular plants2016Inngår i: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 19, nr 1, s. 170-184Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The distribution of water across landscapes affects the diversity and composition of ecological communities, as demonstrated by studies on variation in vascular plant communities along river networks and in relation to groundwater. However, nonvascular plants have been neglected in this regard. Bryophytes are dominant components of boreal flora, performing many ecosystem functions and affecting ecosystem processes, but how their diversity and species composition vary across catchments is poorly known. We asked how terrestrial assemblages of mosses and liverworts respond to variation in (i) catchment size, going from upland-forest to riparian settings along increasingly large streams and (ii) groundwater discharge conditions. We compared the patterns found for liverworts and mosses to vascular plants in the same set of study plots. Species richness of vascular plants and mosses increased with catchment size, whereas liverworts peaked along streams of intermediate size. All three taxonomic groups responded to groundwater discharge in riparian zones by maintaining high species richness further from the stream channel. Groundwater discharge thus provided riparian-like habitat further away from the streams and also in upland-forest sites compared to the non-discharge counterparts. In addition, soil chemistry (C:N ratio, pH) and light availability were important predictors of vascular plant species richness. Mosses and liverworts responded to the availability of specific substrates (stones and topographic hollows), but were also affected by soil C: N. Overall, assemblages of mosses and vascular plants exhibited many similarities in how they responded to hydrological gradients, whereas the patterns of liverworts differed from the other two groups.

  • 43.
    Kuglerová, Lenka
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Sponseller, Ryan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Laudon, Hjalmar
    Sveriges lantbruksuniversitet.
    Malm-Renöfält, Birgitta
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Local and regional processes determine plant species richness in a river-network metacommunity2015Inngår i: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 96, nr 2, s. 381-391Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    River systems form dendritic ecological networks that influence the spatial structure of riverine communities. Few empirical studies have evaluated how regional, dispersal-related processes and local habitat factors interact to govern network patterns of species composition. We explore such interactions in a boreal watershed and show that riparian plant species richness increases strongly with drainage size, i.e., with downstream position in the network. Assemblage composition was nested, with new species successively added downstream. These spatial patterns in species composition were related to a combination of local and regional processes. Breadth in local habitat conditions increased downstream in the network, resulting in higher habitat heterogeneity and reduced niche overlap among species, which together with similar trends in disturbance, allows more species to coexist. Riparian edaphic conditions were also increasingly favorable to more species within the regional pool along larger streams, with greater nitrogen availability (manifested as lower C:N) and more rapid mineralization of C and N (as indicated by ratios of stable isotopes) observed with downstream position in the network. The number of species with capacity for water dispersal increased with stream size providing a mechanistic link between plant traits and the downstream accumulation of species as more propagules arrive from upstream sites. Similarity in species composition between sites was related to both geographical and environmental distance. Our results provide the first empirical evidence that position in the river network drives spatial patterns in riparian plant diversity and composition by the joint influence of local (disturbance, habitat conditions, and breadth) and regional (dispersal) forces.

  • 44.
    Kuglerová, Lenka
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Ågren, Anneli
    Department of Forest Ecology and Management, Swedish University of Agricultural Science, 901 83 Umeå, Sweden.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Laudon, Hjalmar
    Department of Forest Ecology and Management, Swedish University of Agricultural Science, 901 83 Umeå, Sweden.
    Towards optimizing riparian buffer zones: Ecological and biogeochemical implications for forest management2014Inngår i: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 334, s. 74-84Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Riparian forests (RFs) along streams and rivers in forested landscapes provide many ecosystem functions that are important for the biodiversity and biogeochemistry of both terrestrial and aquatic ecosystems. In riverine landscapes, many of these ecological and biogeochemical functions have been found to be maximized in riparian areas with discharge of upland-originating groundwater (GW). This ecological significance, and the fact that riparian areas with GW discharge are important sources of many chemical elements in streams and rivers, makes these places important hotspots in the landscape. The natural functioning of RFs is however threatened by poorly designed management practices, with forestry being one of the most important examples in timber producing regions. Logging operations in riparian, but also in adjoining upland forests, threaten to alter many riparian functions. This effect is accelerated in GW discharge hotspots because of their sensitive soils and the high connectivity with uphill areas. We thus argue that forestry practices should give higher consideration to riparian GW discharge areas, and we demonstrate how improved riparian buffer zone management can be incorporated into every-day forestry planning. We offer a practical tool for more optimized site-specific riparian buffer design by using model-derived high resolution maps with detailed information about wetness and soil–water flow paths within RFs. We describe how such site-specific riparian buffer management differs from fixed-width buffers, which are generally applied in today’s forestry, and address some risks connected to fixed-width buffer management. We conclude that site-specific riparian management, allowing wider buffers at GW discharge areas and more narrow buffers on sites of lower ecological significance (i.e. riparian sites without GW flow paths), would benefit a variety of ecosystem services, mitigate negative effects caused by forestry and create more variable and heterogeneous riparian corridors. Finally, we show examples of how the new forestry planning can be applied.

  • 45.
    Malm-Renöfält, Birgitta
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Effects of hydropower generation and opportunities for environmental flow management in Swedish riverine ecosystems2010Inngår i: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 55, nr 1, s. 49-67Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hydropower is often presented as a clean and renewable energy source that is environmentally preferable to fossil fuels or nuclear power. Hydropower production, however, fundamentally transforms rivers and their ecosystems by fragmenting channels and altering river flows. These changes reduce flow velocity and the number of rapids, and reduce or alter wetland, floodplain and delta ecosystems. Dams disrupt dispersal of riverine organisms and sediment dynamics and may alter riverine biodiversity composition and abundance. Freshwater ecosystems now belong among the world's most threatened ecosystems.

    Water managers are beginning to recognise the need to combine demands for social and economic development with the protection of the resource base on which socioeconomic benefits rely. Environmental flows can help to balance ecosystem and human needs for water, both when constructing new dams and in re-licensing existing dams.

    We briefly review the impacts of hydropower generation on freshwater ecosystems by discussing different types of dams and development, and by providing examples from Sweden of how environmental effects of hydropower production could be mitigated. Special emphasis is given to flow regulation through re-operation of dams.

    Regulated rivers in Sweden were developed with little consideration of ecological effects, with most dams lacking migration pathways or minimum flow releases. There is thus a substantial potential for improvement of ecological conditions, such as naturalisation of flow regimes and reestablishment of connectivity, in regulated river reaches but technical hurdles imply major challenges for rehabilitation and mitigation. Most regulated rivers consist of cascades of consecutive reservoirs and impoundments, further constraining possible actions to improve ecological conditions.

    Most environmental mitigation measures require flow modifications to serve ecosystems, implying reduced power production. An important challenge for river management is to identify situations where measures involving relatively small production losses can have major ecological advantages.

    Climate change during the 21st century is expected to increase runoff in northern and central Sweden and make the annual hydrograph more similar to variation in electricity demand, i.e. a lower spring flood and increased run-off during winter months. This could provide opportunities for operating dams and power stations to the benefit of riverine ecosystems. On the other hand, demands to produce hydropower are likely to increase as fossil fuels are phased out, leading to increased pressures on free-flowing rivers and aquatic ecosystems.

  • 46. Merritt, David M.
    et al.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Consequences of propagule dispersal and river fragmentation for riparian plant community diversity and turnover2010Inngår i: Ecological Monographs, ISSN 0012-9615, E-ISSN 1557-7015, Vol. 80, nr 4, s. 609-626Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The spatial distribution and temporal availability of propagules fundamentallyconstrain plant community development. This study experimentally tested several hypothesesabout the relative roles of wind and water dispersal in colonization and development ofriparian communities along rivers. Through controlling the source of propagules (dispersed bywind, water, or both) reaching newly created, bare river margin sites, we isolated the relativeroles of dispersal and other factors in plant community development over five years.Replicated treatments were established at 12 sites spanning 400 km along two adjacent riversin northern Sweden, one fragmented by a series of dams, the other free-flowing. Bare rivermargins receiving only water-dispersed propagules had significantly higher species richnesscompared to plots receiving only wind-dispersed propagules during the initial two years ofcolonization. Species richness increased annually throughout the study along tranquil andturbulent reaches of the free-flowing river but reached an asymptote at comparatively lowrichness after a single year on the impounded river. Propagule source strongly influencedspecies richness during the initial establishment along both rivers, with richness beingsignificantly higher in plots receiving water-dispersed seeds. This strong treatment effectcontinued to be important through time along the regulated river but diminished inimportance along the free-flowing river where other factors such as soil moisture, lightavailability, and exposure of sites to fluvial disturbance overshadowed the influence ofdispersal pathway in mediating species richness. This suggests that hydrochory (plantdispersal by water) may be more important for maintenance of diversity in regulated systemswhere long-distance dispersal is absent or negligible, but that the rich local propagule sourcealong free-flowing rivers supports high species richness. The number of unique species washigher in water-dispersal plots along both the regulated and free-flowing rivers. This resultsuggests that hydrochory may contribute to temporal variability of sites, may enhance richnessover time, and may have an important role in meta-population and meta-communitydynamics of plant communities through long-distance (and local) dispersal and chancecolonization. Our findings provide experimental evidence that water dispersal of plantpropagules influences colonization dynamics and is important for long-term communitydevelopment in riparian zones.

    Fulltekst (pdf)
    Merritt et al_EcolMonogr2010
  • 47.
    Nilsson, Christer
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Brown, Rebecca L
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Merritt, David M
    The role of hydrochory in structuring riparian and wetland vegetation2010Inngår i: Biological Reviews, ISSN 1464-7931, E-ISSN 1469-185X, Vol. 85, nr 4, s. 837-858Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hydrochory, or the passive dispersal of organisms by water, is an important means of propagule transport, especially forplants. During recent years, knowledge about hydrochory and its ecological consequences has increased considerablyand a substantial body of literature has been produced. Here, we review this literature and define the state of the art ofthe discipline. A substantial proportion of species growing in or near water have propagules (fruits, seeds or vegetativeunits) able to disperse by water, either floating, submerged in flowing water, or with the help of floating vessels.Hydrochory can enable plants to colonize sites out of reach with other dispersal vectors, but the timing of dispersaland mechanisms of establishment are important for successful establishment. At the population level, hydrochorymay increase the effective size and longevity of populations, and control their spatial configuration. Hydrochory isalso an important source of species colonizing recruitment-limited riparian and wetland communities, contributing tomaintenance of community species richness. Dispersal by water may even influence community composition in differentlandscape elements, resulting in landscape-level patterns. Genetically, hydrochory may reduce spatial aggregation ofgenetically related individuals, lead to high gene flow among populations, and increase genetic diversity in populationsreceiving many propagules. Humans have impacted hydrochory in many ways. For example, dams affect hydrochoryby reducing peak flows and hence dispersal capacity, altering the timing of dispersal, and by presenting physical barriersto dispersal, with consequences for riverine plant communities. Hydrochory has been inferred to be an important vectorfor the spread of many invasive species, but there is also the potential for enhancing ecosystem restoration by improvingor restoring water dispersal pathways. Climate change may alter the role of hydrochory by modifying the hydrology ofwater-bodies as well as conditions for propagule release and plant colonization.

  • 48.
    Nilsson, Christer
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Keskitalo, E. Carina H.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Kulturgeografiska institutionen.
    Vlassova, Tatiana
    Institute of Geography, Russian Academy of Sciences, Moscow, Russia.
    Sutinen, Marja-Liisa
    The Finnish Forest Research Institute, Rovaniemi, Finland.
    Moen, Jon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Chapin III, F. Stuart
    Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska, USA.
    Challenges to adaptation in northernmost Europe as a result of global climate change2010Inngår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 39, nr 1, s. 81-84Artikkel i tidsskrift (Annet vitenskapelig)
    Fulltekst (pdf)
    fulltext
  • 49.
    Nilsson, Christer
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Kuglerova, Lenka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Lind, Lovisa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Ström, Lotta
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Boreal riparian vegetation under climate change2013Inngår i: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 16, nr 3, s. 401-410Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Riparian zones in boreal areas such as humid landscapes on minerogenic soils are characterized by diverse, productive, and dynamic vegetation which will rapidly react to climate change. Climate-change models predict that in most parts of the boreal region these zones will be affected by various combinations of increased temperature, less seasonal variation in runoff, increased average discharge, changes in groundwater supply, and a more dynamic ice regime. Increasing temperatures will favor invasion of exotic species whereas species losses are likely to be minor. The hydrologic changes will cause a narrowing of the riparian zone and, therefore, locally reduce species richness whereas effects on primary production are more difficult to predict. More shifts between freezing and thawing during winter will lead to increased dynamics of ice formation and ice disturbance, potentially fostering a more dynamic and species-rich riparian vegetation. Restoration measures that increase water retention and shade, and that reduce habitats for exotic plant species adjacent to rivers can be applied especially in streams and rivers that have been channelized or deprived of their riparian forest to reduce the effects of climate change on riparian ecosystems.

  • 50.
    Nilsson, Christer
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Malmqvist, Björn
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Naiman, Robert J
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Restoring Riverine Landscapes: the Challenge of Identifying Priorities, Reference States, and Techniques2007Inngår i: Ecology & society, ISSN 1708-3087, E-ISSN 1708-3087, Vol. 12, nr 1, s. 16-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This special issue of Ecology and Society on restoring riverine landscapes draws together nine presentations from the Second International Symposium on Riverine Landscapes, convened in August 2004 in Storforsen, Sweden. We summarize three themes related to river restoration: (1) setting priorities, (2) identifying relevant reference conditions, and (3) choosing appropriate techniques. We discuss ways of developing river restoration and provide examples of future needs in sustaining functioning river ecosystems that can support human societies.

    Fulltekst (pdf)
    Nilsson et al_E&S2007
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