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  • 1.
    Albrectsen, Benedicte R
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Witzell, Johanna
    Robinson, Kathryn M
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Wulff, Sören
    Luquez, Virginia MC
    Ågren, Rickard
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Large scale geographic clines of parasite damage to Populus tremula L2010In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 33, no 3, p. 483-493Article in journal (Refereed)
    Abstract [en]

    In conclusion, clines of Phyllocnistis were stronger and more persistent compared to Melampsora, which showed contrasting clines of varying strength. Our data thus support the assumption of the GMTC model that clines exist in the border between hot and cold spots and that they may be less persistent for parasites with an elevated gene flow, and/or for parasites which cover relatively larger hot spots surrounded by fewer cold spots.

  • 2. De Block, Marjan
    et al.
    Slos, Stefanie
    Johansson, Frank
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Stoks, Robby
    Integrating life history and physiology to understand latitudinal size variation in a damselfly2008In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 31, p. 115-123Article in journal (Refereed)
    Abstract [en]

    Our understanding of latitudinal life history patterns may benefit by jointly considering age and mass at maturity and growth rate. Additional insight may be gained by exploring potential constraints through pushing growth rates to their maximum and scoring physiological cost-related variables. Therefore, we reared animals of a univoltine Spanish and Belgian population and of a semivoltine Swedish population of the damselfly Enallagma cyathigerum (spanning a latitude gradient of ca 2350 km) in a common environment from the eggs until adult emergence and exposed them to a transient starvation period to induce compensatory growth. Besides age and mass at maturity and growth rate we also scored investment in energy storage (i.e. triglycerides) and immune function (i.e. total activity of phenoloxidase). At emergence, body mass was greater in Spain and Sweden and lower in Belgium, suggesting a genetic component for the U-shaped latitudinal pattern that was found also in a previous study based on field-collected adults. The mass difference between univoltine populations can be explained by the shorter development time in the Belgian population, and this despite a higher growth rate, a pattern consistent with undercompensating countergradient variation. In line with the assumed shorter growth seasons, Belgian and Swedish animals showed higher routine growth rates and compensatory growth after transient starvation. Despite a strong link with metabolic rates (as measured by oxygen consumption) populations with higher routine growth rates had no lower fat content and had higher immune function (i.e. immune function decreased from Sweden to Spain), which was unexpected. Rapid compensatory growth did, however, result in a lowered immune function. This may contribute to the absence of perfect compensating countergradient variation in the Belgian population and the lowest routine growth rates in the Spanish population. Our results underscore the importance of integrating key life historical with physiological traits for understanding latitudinal population differentiation.

  • 3. De Frenne, Pieter
    et al.
    Graae, Bente J
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Kolb, Annette
    Shevtsova, Anna
    Baeten, Lander
    Brunet, Jörg
    Chabrerie, Olivier
    Cousins, Sara A O
    Decocq, Guillaume
    Dhondt, Rob
    Diekmann, Martin
    Gruwez, Robert
    Heinken, Thilo
    Hermy, Martin
    Öster, Mathias
    Saguez, Robert
    Stanton, Sharon
    Tack, Wesley
    Vanhellemont, Margot
    Verheyen, Kris
    An intraspecific application of the leaf-height-seed ecology strategy scheme to forest herbs along a latitudinal gradient2011In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 34, no 1, p. 132-140Article in journal (Refereed)
    Abstract [en]

    We measured LHS traits in 41 Anemone nemorosa and 44 Milium effusum populations along a 1900-2300 km latitudinal gradient from N France to N Sweden. We then applied multilevel models to identify the effects of regional (temperature, latitude) and local (soil fertility and acidity, overstorey canopy cover) environmental factors on LHS traits. Both species displayed a significant 4% increase in plant height with every degree northward shift (almost a two-fold plant height difference between the southernmost and northernmost populations). Neither seed mass nor SLA showed a significant latitudinal cline. Temperature had a large effect on the three LHS traits of Anemone. Latitude, canopy cover and soil nutrients were related to the SLA and plant height of Milium. None of the investigated variables appeared to be related to the seed mass of Milium. The variation in LHS traits indicates that the ecological strategy determined by the position of each population in this three-factor triangle is not constant along the latitudinal gradient. The significant increase in plant height suggests greater competitive abilities for both species in the northernmost populations. We also found that the studied environmental factors affected the LHS traits of the two species on various scales: spring-flowering Anemone was affected more by temperature, whereas early-summer flowering Milium was affected more by local and other latitude-related factors. Finally, previously reported cross-species correlations between LHS traits and latitude were generally unsupported by our within-species approach.

  • 4. Dunn, RM
    et al.
    Colwell, RK
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    The river domain: why are there more species halfway up the river?2006In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 29, no 2, p. 251-259Article in journal (Refereed)
  • 5. Hoset, Katrine S.
    et al.
    Kyro, Kukka
    Oksanen, Tarja
    Oksanen, Lauri
    Olofsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Spatial variation in vegetation damage relative to primary productivity, small rodent abundance and predation2014In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 37, no 9, p. 894-901Article in journal (Refereed)
    Abstract [en]

    The relative importance of top-down and bottom-up mechanisms in shaping community structure is still a highly controversial topic in ecology. Predatory top-down control of herbivores is thought to relax herbivore impact on the vegetation through trophic cascades. However, trophic cascades may be weak in terrestrial systems as the complexity of food webs makes responses harder to predict. Alternatively, top-down control prevails, but the top-level (predator or herbivore) changes according to productivity levels. Here we show how spatial variation in the occurrence of herbivores (lemmings and voles) and their predators (mustelids and foxes) relates with grazing damage in landscapes with different net primary productivity, generating two and three trophic level communities, during the 2007 rodent peak in northern Norway. Lemmings were most abundant on the unproductive high-altitude tundra, where few predators were present and the impact of herbivores on vegetation was strong. Voles were most common on a productive, south facing slope, where numerous predators were present, and the impacts of herbivores on vegetation were weak. The impact of herbivores on the vegetation was strong only when predators were not present, and this cannot be explained by between-habitat differences in the abundance of plant functional groups. We thus conclude that predators influence the plant community via a trophic cascade in a spatial pattern that support the exploitation ecosystems hypothesis. The responses to grazing also differed between plant functional groups, with implications for short and long-term consequences for plant communities.

  • 6.
    Johansson, Helena
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Centre of Excellence in Biological Interactions, Dept of Biosciences, Helsinki Univ., PO Box 65, FI-00014 Helsinki.
    Stoks, Robby
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Centre of Excellence in Biological Interactions, Dept of Biosciences, Helsinki Univ., PO Box 65, FI-00014 Helsinki.
    Nilsson-Örtman, Viktor
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Centre of Excellence in Biological Interactions, Dept of Biosciences, Helsinki Univ., PO Box 65, FI-00014 Helsinki.
    Ingvarsson, Pär
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Centre of Excellence in Biological Interactions, Dept of Biosciences, Helsinki Univ., PO Box 65, FI-00014 Helsinki.
    Johansson, Frank
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Centre of Excellence in Biological Interactions, Dept of Biosciences, Helsinki Univ., PO Box 65, FI-00014 Helsinki.
    Large-scale patterns in genetic variation, gene flow and differentiation in five species of European Coenagrionid damselfly provide mixed support for the central-marginal hypothesis2013In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 36, no 6, p. 744-755Article in journal (Refereed)
    Abstract [en]

    Recently, an increased effort has been directed towards understanding the distribution of genetic variation within and between populations, particularly at central and marginal areas of a species' distribution. Much of this research is centred on the central-marginal hypothesis, which posits that populations at range margins are sparse, small and genetically diminished compared to those at the centre of a species' distribution range. We tested predictions derived from the central-marginal hypothesis for the distribution of genetic variation and population differentiation in five European Coenagrionid damselfly species. We screened genetic variation (microsatellites) in populations sampled in the centre and margins of the species' latitudinal ranges, assessed genetic diversity (HS) in the populations and the distribution of this genetic diversity between populations (FST). We further assessed genetic substructure and migration with Bayesian assignment methods, and tested for significant associations between genetic substructure and bioclimatic and spatial (altitude and latitude) variables, using general linearized models. We found no general adherence to the central-marginal hypothesis; instead we found that other factors such as historical or current ecological factors often better explain the patterns uncovered. This was illustrated in Coenagrion mercuriale whose colonisation history and behaviour most likely led to the observation of a high genetic diversity in the south and lower genetic diversity with increasing latitude, and in C. armatum and C. pulchellum whose patterns of low genetic diversity coupled with the weakest genetic differentiation at one of their range margins suggested, respectively, possible range shifts and recent, strong selection pressure.

  • 7.
    Jonsson Cabrajic, Anna V
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Moen, Jon
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Palmqvist, Kristin
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Predicting growth of mat-forming lichens on a landscape scale: comparing models with different complexities2010In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 33, no 5, p. 949-960Article in journal (Refereed)
    Abstract [en]

    During the 20th century, forestry practices has adversely affected lichen-rich habitats. Mat-forming lichens are important components of the vegetation of boreal and arctic ecosystems and are the main reindeer forage during the winter. To support the long-term management of lichens in such habitats we developed models for predicting the growth of two common species. The lichens were transplanted across northern Scandinavia along a west-east gradient varying in precipitation, temperature and irradiance. Growth was recorded seasonally over 16 months and ranged from −4.8 to 34.6% and −12.7 to 34.7% dry weight change for Cetraria stellaris and Cladina islandica, respectively. Growth was light limited below canopies with more than ca 60% cover and highest at the more humid sites when light levels were optimal. The models were based on various meteorological parameters, irradiance, physiological data and lichen hydration status; the latter was derived from a recently developed lichen hydration model. Our models' abilities to predict growth, both annually and seasonally (i.e. in summer), were evaluated in relation to their complexity and their potential usefulness from a management perspective. One parameter related to irradiance (the logarithm of site openness) was valuable in the prediction of annual growth for both species and could, in combination with precipitation, explain 52% of the variation in annual growth for C. stellaris and, in combination with total wet time and the irradiance received while wet, explain 66% of the variation in annual growth for C. islandica. The best simplified model explained 43% of the variation in annual growth for C. stellaris, using stem basal area and the annual normal temperature, and 24% for C. islandica using basal area alone. It is concluded that ensuring sufficient irradiance below the forest canopy is of crucial importance in the long-term management of mat-forming lichens and that simplified models can be used to identify appropriate habitats.

  • 8. Lembrechts, Jonas J.
    et al.
    Alexander, Jake M.
    Cavieres, Lohengrin A.
    Haider, Sylvia
    Lenoir, Jonathan
    Kueffer, Christoph
    McDougall, Keith
    Naylor, Bridgett J.
    Nunez, Martin A.
    Pauchard, Anibal
    Rew, Lisa J.
    Nijs, Ivan
    Milbau, Ann
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Research Inst. for Nature and Forest INBO, Dept of Biodiversity and Natural Environment, Brussels, Belgium.
    Mountain roads shift native and non-native plant species' ranges2017In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 40, no 3, p. 353-364Article in journal (Refereed)
    Abstract [en]

    Roads are known to act as corridors for dispersal of plant species. With their variable microclimate, role as corridors for species movement and reoccurring disturbance events, they show several characteristics that might influence range dynamics of both native and non-native species. Previous research on plant species ranges in mountains however seldom included the effects of roads. To study how ranges of native and non-native species differ between roads and adjacent vegetation, we used a global dataset of plant species composition along mountain roads. We compared average elevation and range width of species, and used generalized linear mixed models (GLMMs) to compile their range optimum and amplitude. We then explored differences between roadside and adjacent plots based on a species' origin (native vs non-native) and nitrogen and temperature affinity. Most non-native species had on average higher elevational ranges and broader amplitudes in roadsides. Higher optima for non-native species were associated with high nitrogen and temperature affinity. While lowland native species showed patterns comparable to those in non-native species, highland native species had significantly lower elevational ranges in roadsides compared to the adjacent vegetation. We conclude that roadsides indeed change the elevational ranges of a variety of species. These changes are not limited to the expansion of non-native species along mountain roads, but also include both upward and downward changes in ranges of native species. Roadsides may thus facilitate upward range shifts, for instance related to climate change, and they could serve as corridors to facilitate migration of alpine species between adjacent high-elevation areas. We recommend including the effects of mountain roads in species distribution models to fine-tune the predictions of range changes in a warming climate.

  • 9.
    Olofsson, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Kitti, Heidi
    Rautiainen, Pirjo
    Stark, Sari
    Oksanen, Lauri
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Effects of summer grazing by reindeer on composition of vegetation, productivity and nitrogen cycling2001In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 24, no 1, p. 13-24Article in journal (Refereed)
    Abstract [en]

    In this study, we investigated the effect of reindeer grazing on tundra heath vegetation in northern Norway. Fences. erected 30 yr ago, allowed us to compare winter grazed, lightly summer grazed and heavily summer grazed vegetation at four different sites. At two sites, graminoids dominated the heavily grazed zone completely, while ericoid dwarf shrubs had almost disappeared. In the other two areas, the increase of graminoids was almost significant. At one of the sites where graminoids dominated the heavily grazed area. we also measured plant biomass, primary production and nitrogen cycling. In this site: heavy grazing increased primary production and rate of nitrogen cycling, while moderate grazing decreased primary production. These results were inconsistent with the view that the highest productivity is found at intermediate grazing pressure. These results rather support the hypothesis that intensive grazing can promote a transition of moss-rich heath tundra into productive, graminoid-dominated steppe-like tundra vegetation. More over the results suggests that intermittent intensive reindeer grazing can enhance productivity of summer ranges.

  • 10. Shackelford, Nancy
    et al.
    Starzomski, Brian M.
    Banning, Natasha C.
    Battaglia, Loretta L.
    Becker, Alistair
    Bellingham, Peter J.
    Bestelmeyer, Brandon
    Catford, Jane A.
    Dwyer, John M.
    Dynesius, Mats
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Gilmour, James
    Hallett, Lauren M.
    Hobbs, Richard J.
    Price, Jodi
    Sasaki, Takehiro
    Tanner, Edmund V. J.
    Standish, Rachel J.
    Isolation predicts compositional change after discrete disturbances in a global meta-study2017In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 40, no 11, p. 1256-1266Article in journal (Refereed)
    Abstract [en]

    Globally, anthropogenic disturbances are occurring at unprecedented rates and over extensive spatial and temporal scales. Human activities also affect natural disturbances, prompting shifts in their timing and intensities. Thus, there is an urgent need to understand and predict the response of ecosystems to disturbance. In this study, we investigated whether there are general determinants of community response to disturbance across different community types, locations, and disturbance events. We compiled 14 case studies of community response to disturbance from four continents, twelve aquatic and terrestrial ecosystem types, and eight different types of disturbance. We used community compositional differences and species richness to indicate community response. We used mixed-effects modeling to test the relationship between each of these response metrics and four potential explanatory factors: regional species pool size, isolation, number of generations passed, and relative disturbance intensity. We found that compositional similarity was higher between pre- and post-disturbance communities when the disturbed community was connected to adjacent undisturbed habitat. The number of generations that had passed since the disturbance event was a significant, but weak, predictor of community compositional change; two communities were responsible for the observed relationship. We found no significant relationships between the factors we tested and changes in species richness. To our knowledge, this is the first attempt to search for general drivers of community resilience from a diverse set of case studies. The strength of the relationship between compositional change and isolation suggests that it may be informative in resilience research and biodiversity management.

  • 11.
    Zinko, Ursula
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Dynesius, Mats
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Seibert, Jan
    Department of Physical Geography and Quaternary Geology, Stockholm University.
    The role of soil pH in linking groundwater flow and plant species density in boreal forest landscapes2006In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 29, no 4, p. 515-524Article in journal (Refereed)
    Abstract [en]

    In hilly boreal landscapes topography governs groundwater flow which strongly influences soil development, and thus vegetation composition. Soil pH is known to correlate well with plant species density and composition, but in boreal forests this relationship has been little studied. Previously, we successfully used a topography-based hydrological index, the topographical wetness index (TWI), as an approximation of the variation in groundwater flow to predict local plant species density in a boreal forest landscape. Data on species indicator values demonstrated that soil pH can be an important soil variable linking groundwater flow and plant species density. In the present paper we explore this link by relating measured soil pH to species numbers of vascular plants and TWI in 200-m2 plots within two boreal forest landscapes, differing in average soil pH. The two landscapes showed almost identical relationships between plant species number and soil pH, implying that this relationship is robust. The landscapes also had similar relationships between soil pH and TWI as well as between plant species number and TWI except at high TWI values, which indicate groundwater discharge areas. In these areas soil pH and plant species numbers were higher in the high-pH landscape at any given TWI value. We conclude that for predictive mapping of the species density of vascular plants in boreal forests, soil pH is a major factor. However, TWI as a measure of groundwater flow is a practical alternative predictor.

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