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  • 1.
    Christensen, Pernilla
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Hörnfeldt, Birger
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Habitat preference of Clethrionomys rufocanus in boreal Sweden2006In: Landscape Ecology, ISSN 0921-2973, E-ISSN 1572-9761, Vol. 21, no 2, p. 185-194Article in journal (Refereed)
    Abstract [en]

    A long-term decline of vole populations in boreal Sweden, especially of the grey-sided vole (Clethrionomysrufocanus Sund.), has been revealed by snap-trapping in 1971–2004. We identified important habitats forthe grey-sided vole by mapping the distribution of cumulated number of reproductive females in 1971–1978, prior to the major decline in the 1980s. Mean abundance of C. rufocanus was higher in the western(inland) than eastern (coastland) part of the study area. As the inland appeared to represent the most, as faras we know, pristine, abundant part of the population, we based identification of high quality habitats oninland data only. Four habitats were more important than others and yielded nearly 86% of the reproductivefemales in spring: (1) forests of dry, (2) moist and (3) wet/hydric dwarf-shrub type, in addition to (4)forest/swamp complexes rich in dwarf-shrubs. The latter three habitats were used more frequently thanexpected from their occurrence in the landscape. Still, the variation in density of reproductive femaleswithin patches of the same habitat was frequently high. This suggested that habitat composition in thesurrounding landscape, perhaps may have affected local vole density at the patch scale. Clear-cut samplingplots appeared to be low-frequently used by reproductive females, but also by males and immatures. Inconclusion, our study indicated the importance of also studying habitat at a larger scale than that of thepatch to get a deeper understanding on how habitat influences local and regional densities and populationdynamics of C. rufocanus.

  • 2. Ecke, Frauke
    et al.
    Christensen, Pernilla
    Rentz, Ralf
    Nilsson, Mats
    Sandström, Per
    Hörnfeldt, Birger
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Vindelfjällens forskningsstation, Ammarnäs, Sweden; Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden .
    Landscape structure and the long-term decline of cyclic grey-sided voles in Fennoscandia2010In: Landscape Ecology, ISSN 0921-2973, E-ISSN 1572-9761, Vol. 25, no 4, p. 551-560Article in journal (Refereed)
    Abstract [en]

    Changes in forest landscape structure have been suggested as a likely contributing factor behind the long-term decline in the numbers of cyclic grey-sided voles (Clethrionomys rufocanus) in northern Fennoscandian lowland regions in contrast to mountain regions due to the absence of forest management in the mountains. This study, for the first time, formally explored landscape structure in 29 lowland (LF) and 14 mountain forest (MF) landscapes (each 2.5 x 2.5 km) in northern Sweden, and related the results to the cumulated spring trapping index of the grey-sided vole in 2002-2006. The grey-sided vole showed striking contrasts in dynamics close in space and time. The MF landscapes were characterized by larger patches and less fragmentation of preferred forest types. The grey-sided vole was trapped in all of 14 analyzed MF landscapes but only in three out of 29 of the LF landscapes. MF and LF landscapes with grey-sided vole occurrence were characterized by similar focal forest patch size (mean 357 ha, minimum 82 ha and mean 360 ha, minimum 79 ha, respectively). In contrast, these MF compared to the LF landscapes were characterized by larger patches of preferred forest types and less fragmented preferred forest types and by a lower proportion of clear-cut areas. The present results suggest that landscape structure is important for the abundance of grey-sided voles in both regions. However, in the mountains the change from more or less seasonal dynamics to high-amplitude cycles between the mid 1990s and 2000s cannot be explained by changes in landscape structure.

  • 3.
    Gimmi, Urs
    et al.
    Research Unit Landscape Dynamics, Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland.
    Poulter, Ben
    Research Unit Landscape Dynamics, Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland; Laboratoire des Sciences du Climat et l'Environement (LSCE), Gif sur Yvette, France.
    Wolf, Annett
    Forest Ecology, Department of Environmental Sciences, Institute of Terrestrial Ecosystems, Swiss Federal Institute of Technology ETH, .
    Portner, H.
    Forest Ecology, Department of Environmental Sciences, Institute of Terrestrial Ecosystems, Swiss Federal Institute of Technology ETH, .
    Weber, P
    Research Unit Soil Sciences, Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland.
    Bürgi, M.
    Research Unit Landscape Dynamics, Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland.
    Soil carbon pools in Swiss forests show legacy effects from historic forest litter raking2013In: Landscape Ecology, ISSN 0921-2973, E-ISSN 1572-9761, Vol. 28, no 5, p. 835-846Article in journal (Refereed)
    Abstract [en]

    Globally, forest soils contain twice as much carbon as forest vegetation. Consequently, natural and anthropogenic disturbances affecting carbon accumulation in forest soils can alter regional to global carbon balance. In this study, we evaluate the effects of historic litter raking on soil carbon stocks, a former forest use which used to be widespread throughout Europe for centuries. We estimate, for Switzerland, the carbon sink potential in current forest soils due to recovery from past litter raking ('legacy effect'). The year 1650 was chosen as starting year for litter raking, with three different end years (1875/1925/1960) implemented for this forest use in the biogeochemical model LPJ-GUESS. The model was run for different agricultural and climatic zones separately. Number of cattle, grain production and the area of wet meadow have an impact on the specific demand for forest litter. The demand was consequently calculated based on historical statistical data on these factors. The results show soil carbon pools to be reduced by an average of 17 % after 310 years of litter raking and legacy effects were still visible 130 years after abandonment of this forest use (2 % average reduction). We estimate the remaining carbon sink potential in Swiss forest due to legacy effects from past litter raking to amount to 158,000 tC. Integrating historical data into biogeochemical models provides insight into the relevance of past land-use practices. Our study underlines the importance of considering potentially long-lasting effects of such land use practices for carbon accounting.

  • 4.
    Hörnfeldt, Birger
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Christensen, Pernilla
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Sandström, Per
    Ecke, Fraucke
    Long-term decline and local extinction of Clethrionomys rufocanus in boreal Sweden2006In: Landscape Ecology, ISSN 0921-2973, E-ISSN 1572-9761, Vol. 21, p. 1135-1150Article in journal (Refereed)
    Abstract [en]

    Over the past three decades in boreal Sweden, there has been a long-term decline of cyclic sympatric voles,leading to local extinctions of the most affected species, the grey-sided vole (Clethrionomys rufocanus). Wemonitored this decline by snap-trapping on 58 permanent plots spread over 100 km2 in spring and fall from fall1971–2003. The reason for the decline is largely unknown, although a common major factor is likely to beinvolved in the decline of C. rufocanus and of the coexisting voles.However, here we deal with the reasonabilityof one complementary hypothesis, the habitat fragmentation hypothesis, which assumes that part of thedecline of C. rufocanus is caused by habitat (forest) destruction. There was considerable local variation in thedecline among the 58 1-ha sampling plots, with respect to both density and timing of the decline; however, alldeclines ended up with local extinction almost without exception. Local declines were not associated withhabitat destruction by clear-cutting within sampling-plots, as declines started about equally often before asafter clear-cutting, which suggested that habitat destruction outside sampling plots could be involved. In amultiple regression analysis, local habitat preference (LHP; expressed as a ratio of observed to expectednumber of voles trapped per habitat) together with two habitat variables in the surrounding (2.5 · 2.5 km2)landscape matrix explained56%of the variation among local cumulated densities of C. rufocanus and hence oflocal time-series.LHPwas positively correlated and explained31%of the variation, while connectivity amongclear-cuts was negatively correlated and proximity among xeric-mesic mires was positively correlated andexplained additional 16% and 9%, respectively. Even if the overall decline cannot be connected to local clearcuttingon sampling-plots, clear-cutting and hence habitat fragmentation/destruction in the surroundinglandscapes potentially influenced grey-sided vole numbers negatively.

  • 5. Norman, Anita J.
    et al.
    Stronen, Astrid V.
    Fuglstad, Geir-Arne
    Ruiz-Gonzalez, Aritz
    Kindberg, Jonas
    Street, Nathaniel R.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Spong, Goran
    Landscape relatedness: detecting contemporary fine-scale spatial structure in wild populations2017In: Landscape Ecology, ISSN 0921-2973, E-ISSN 1572-9761, Vol. 32, no 1, p. 181-194Article in journal (Refereed)
    Abstract [en]

    Methods for detecting contemporary, fine-scale population genetic structure in continuous populations are scarce. Yet such methods are vital for ecological and conservation studies, particularly under a changing landscape. Here we present a novel, spatially explicit method that we call landscape relatedness (LandRel). With this method, we aim to detect contemporary, fine-scale population structure that is sensitive to spatial and temporal changes in the landscape. We interpolate spatially determined relatedness values based on SNP genotypes across the landscape. Interpolations are calculated using the Bayesian inference approach integrated nested Laplace approximation. We empirically tested this method on a continuous population of brown bears (Ursus arctos) spanning two counties in Sweden. Two areas were identified as differentiated from the remaining population. Further analysis suggests that inbreeding has occurred in at least one of these areas. LandRel enabled us to identify previously unknown fine-scale structuring in the population. These results will help direct future research efforts, conservation action and aid in the management of the Scandinavian brown bear population. LandRel thus offers an approach for detecting subtle population structure with a focus on contemporary, fine-scale analysis of continuous populations.

  • 6.
    Olofsson, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Hulme, P H
    Oksanen, L
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Suominen, O
    Effects of mammalian herbivores on revegetation of disturbed areas in different locations in the forest-tundra ecotone in northern Fennoscandia2005In: Landscape Ecology, ISSN 0921-2973, E-ISSN 1572-9761, Vol. 20, p. 351-359Article in journal (Refereed)
    Abstract [en]

    Herbivores influence the structure of plant communities in arctic-alpine ecosystems. However, little is known of the effect of herbivores on plant colonisation following disturbance, and on its variability depending on the identity of herbivores and the characteristics of the habitats. To quantify the role of large and small vertebrate herbivores, we established exclosures of two different mesh sizes around disturbed subplots in forest and nearby tundra habitats in four contrasting locations in the forest-tundra ecotone in northernmost Sweden and Norway. The study revealed that herbivores influenced the abundance but not the species composition of regenerating vegetation. Gaps were colonised by the dominant species in the surrounding vegetation. The only exception to this expectation was Empetrum nigrum, which failed to colonise gaps even though it dominated undisturbed vegetation. Significant effects of herbivory were only detected when both small and large herbivores were excluded. Herbivores decreased the abundance of three of the most common species Vaccinium myrtillus, Vaccinium vitis idaea, and Deschampsia flexuosa. The effect of herbivory on the abundance of these three species did not differ between habitats and locations. However, the composition of the regenerating vegetation differed between habitats and locations. The disturbance treatment increased the species richness on the scale of plots, habitats, and sites. However, on the scale of whole locations, all species found in disturbed areas were also found in undisturbed areas, suggesting that the natural disturbance regime in arctic landscapes is high enough to sustain colonising species.

  • 7.
    Renöfält, Birgitta Malm
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jansson, Roland
    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.
    Spatial patterns of plant invasiveness in a riparian corridor2005In: Landscape Ecology, ISSN 0921-2973, E-ISSN 1572-9761, Vol. 20, no 2, p. 165-176Article in journal (Refereed)
    Abstract [en]

    Analysis of landscape-scale patterns of plant invasiveness can assist in interpreting spatial patterns of plant species richness. We investigated downstream variation in plant invasiveness in the riparian corridor of the free-flowing Vindel River in northern Sweden by introducing seeds of an alien species, Helianthus annuus, in 0.25 m2 plots of natural vegetation from mountain headwaters to the coast and found a significant downstream pattern with middle reaches having the highest invasiveness. We related invasiveness to species richness, both on a reach scale (200-m long stretches of riverbank encompassing the experimental plots) and on the scale of experimental plots. We found no significant correlation between plant invasiveness and species richness, neither at the reach nor at the plot scale. The number of available soil substrates shows a significant positive quadratic relationship with location along the river and substrate fineness shows a near significant negative quadratic relationship with location along the river, with middle reaches having coarser substrates. Several studies have shown that plant species richness in riparian corridors often exhibits a quadratic pattern with highest species richness in the middle reaches of a river, similar to the pattern we found for invasiveness. Although species richness per se might not be a primary factor for invasibility, the same habitat conditions as those supporting plant species richness, can help in explaining large-scale patterns of plant invasion in riparian zones.

  • 8.
    Starr, Scott M.
    et al.
    Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, 35487, USA and Department of Biological Sciences, Texas Tech University, Box 43131, Lubbock, TX, 79409-3131, USA.
    Benstead, Jonathan P.
    Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, 35487, USA.
    Sponseller, Ryan A.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Spatial and temporal organization of macroinvertebrate assemblages in a lowland floodplain ecosystem2014In: Landscape Ecology, ISSN 0921-2973, E-ISSN 1572-9761, Vol. 29, no 6, p. 1017-1031Article in journal (Refereed)
    Abstract [en]

    An important goal in ecology is to understand controls on community structure in spatially and temporally heterogeneous landscapes, a challenge for which riverine floodplains provide ideal laboratories. We evaluated how spatial position, local habitat features, and seasonal flooding interact to shape aquatic invertebrate community composition in an unregulated riverine floodplain in western Alabama (USA). We quantified sediment invertebrate assemblages and habitat variables at 23 sites over a 15-month period. Dissolved oxygen (DO) varied seasonally and among habitats, with sites less connected to the river channel experiencing frequent hypoxia (< 2 mg O-2 L-1) at the sediment-water interface. Differences in water temperature among sites were lowest (< 1 A degrees C) during winter floodplain inundation, but increased to > 14 A degrees C during spring and summer as sites became isolated. Overall, local habitat conditions were more important in explaining patterns in assemblage structure than was spatial position in the floodplain (e.g., distance to the main river channel). DO was an important predictor of taxonomic richness among sites, which was highest where hydrologic connections to the main river channel were strongest. Compositional heterogeneity across the floodplain was lowest immediately following inundation and increased as individual sites became hydrologically isolated. Our results illustrate how geomorphic structure and seasonal flooding interact to shape floodplain aquatic assemblages. The flood pulse of lowland rivers influences biodiversity through effects of connectivity on hydrologic flushing in different floodplain habitats, which may prevent the development of harsh environmental conditions that exclude certain taxa. Such interactions highlight the ongoing consequences of river regulation for taxonomically diverse floodplain ecosystems.

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