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1.
Frauke Ecke Pernilla Christensen Per Sandström Birger Hörnfeldt 《Landscape Ecology》2006,21(4):485-497
Several studies indicate a long-term decline in numbers of different species of voles in northern Fennoscandia. In boreal Sweden, the long-term decline is most pronounced in the grey-sided vole (Clethrionomys rufocanus). Altered forest landscape structure has been suggested as a possible cause of the decline. However, habitat responses of grey-sided voles at the landscape scale have never been studied. We analyzed such responses of this species in lowland forests in Västerbotten, northern Sweden. Cumulated spring densities representing 22 local time series from 1980–1999 were obtained by a landscape sampling design and were related to the surrounding landscape structure of 2.5×2.5 km plots centred on each of the 22 1-ha trapping plots. In accordance with general knowledge on local habitat preferences of grey-sided voles, our study supported the importance of habitat variables such as boulder fields and old-growth pine forest at the landscape scale. Densities were negatively related to clear cuts. Habitat associations were primarily those of landscape structure related to habitat fragmentation, distance between habitat patches and patch interspersion rather than habitat patch type quantity. Local densities of the grey-sided vole were positively and exponentially correlated with spatial contiguity (measured with the fragmentation index) of old-growth pine forest, indicating critical forest fragmentation thresholds. Our results indicate that altered land use might be involved in the long-term decline of the grey-sided vole in managed forest areas of Fennoscandia. We propose two further approaches to reveal and test responses of this species to changes in landscape structure. 相似文献
2.
A long-term decline of vole populations in boreal Sweden, especially of the grey-sided vole (Clethrionomys rufocanus Sund.), has been revealed by snap-trapping in 1971–2004. We identified important habitats for the 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 far as we know, pristine, abundant part of the population, we based identification of high quality habitats on inland
data only. Four habitats were more important than others and yielded nearly 86% of the reproductive females 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 than expected from their occurrence in the landscape. Still, the variation
in density of reproductive females within patches of the same habitat was frequently high. This suggested that habitat composition
in the surrounding landscape, perhaps may have affected local vole density at the patch scale. Clear-cut sampling plots appeared
to be low-frequently used by reproductive females, but also by males and immatures. In conclusion, our study indicated the
importance of also studying habitat at a larger scale than that of the patch to get a deeper understanding on how habitat
influences local and regional densities and population dynamics of C. rufocanus. 相似文献
3.
Frauke Ecke Pernilla Christensen Ralf Rentz Mats Nilsson Per Sandström Birger Hörnfeldt 《Landscape Ecology》2010,25(4):551-560
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 × 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. 相似文献
4.
Effective conservation management for species that function as metapopulations requires an understanding of population dynamics
at the landscape scale. The water vole, Arvicola amphibius, is one such species. Water voles have recently undergone a significant decline in the UK, as a result of habitat loss and
predation from the introduced American mink, Neovison vison. Large reed bed and grazing marsh sites can provide refuge habitats for water voles from mink predation, in which case populations
within these sites could sustain metapopulations in the surrounding landscape where conditions are less favourable. We carried
out a study using a stochastic patch occupancy model to determine the long term viability of water vole metapopulations in
the wider landscape around a series of extensive reed bed and grazing marsh sites designated as National Key Sites for water
voles. The results of our model simulations show that a large protected core site, or mainland, is essential in maintaining
the long term viability of these systems. Our results also show how these metapopulations could be enhanced by increasing
patch numbers through habitat creation and/or restoration and suggest what the minimum effective size of created or restored
patches should be. The study shows how population modelling can provide insight into some effective practical ways of enhancing
the viability of water vole metapopulations at the landscape scale. Furthermore it demonstrates that extensive wetlands are
an appropriate focus for water vole conservation measures. 相似文献
5.
This study examined the effects of habitat fragmentation on meadow vole (Microtus pennsylvanicus) population dynamics in experimental landscape patches. The study was conducted from May–November 1993 at the Miami University
Ecology Research Center. Eight 0.1-ha small mammal enclosures were used. Four enclosures contained a 160 m2 nonfragmented patch and four enclosures contained four 40 m2 fragmented patches. Thus, each treatment was replicated 4 times in a systematic research design. The patches in both treatments
contained high-quality habitat surrounded by low-quality matrix. Six pairs of adult meadow voles were released in each enclosure
on 27 May 1993. Populations were monitored by live-trapping and radio-telemetry methods. Significantly greater densities of
female voles were found during October in the fragmented treatment compared to the nonfragmented treatment. Also, significantly
more females than males were found in the fragmented treatment compared to the nonfragmented treatment for the total study
period. Significantly more subadult and juvenile males were found in the matrix versus the patch of the nonfragmented treatment
compared to the fragmented treatment. Males in the fragmented treatment had significantly greater mean home range size than
males or females in the nonfragmented treatment. There appears to exist a relationship between patch fragmentation and the
social structure of meadow vole populations; this relationship appears to function as a population regulatory mechanism. 相似文献
6.
Martin Mikoláš Martin Tejkal Tobias Kuemmerle Patrick Griffiths Miroslav Svoboda Tomáš Hlásny Pedro J. Leitão Robert C. Morrissey 《Landscape Ecology》2017,32(1):163-179
Context
Distribution and connectivity of suitable habitat for species of conservation concern is critical for effective conservation planning. Capercaillie (Tetrao urogallus), an umbrella species for biodiversity conservation, is increasingly threatened because of habitat loss and fragmentation.Objective
We assessed the impact of drastic changes in forest management in the Carpathian Mountains, a major stronghold of capercaillie in Europe, on habitat distribution and connectivity.Methods
We used field data surveys with a forest disturbance dataset for 1985–2010 to map habitat suitability, and we used graph theory to analyse habitat connectivity.Results
Climate, topography, forest proportion and fragmentation, and the distance to roads and settlements best identified capercaillie presence. Suitable habitat area was 7510 km2 in 1985; by 2010, clear-cutting had reduced that area by 1110 km2. More suitable habitat was lost inside protected areas (571 km2) than outside (413 km2). Habitat loss of 15 % reduced functional connectivity by 33 % since 1985.Conclusions
Forest management, particularly large-scale clear-cutting and salvage logging, have substantially diminished and fragmented suitable capercaillie habitat, regardless of the status of forest protection. Consequently, larger areas with suitable habitat are now isolated and many patches are too small to sustain viable populations. Given that protection of capercaillie habitat would benefit many other species, including old-growth specialists and large carnivores, conservation actions to halt the loss of capercaillie habitat is urgently needed. We recommend adopting policies to protect natural forests, limiting large-scale clear-cutting and salvage logging, implementing ecological forestry, and restricting road building to reduce forest fragmentation.7.
Threshold levels of habitat composition for the presence of the long-tailed tit (Aegithalos caudatus) in a boreal landscape 总被引:4,自引:0,他引:4
We assessed the habitat patch occupancy of a deciduous-mixed forest specialist, the long-tailed tit (Aegithalos caudatus), in a 1000 km2 conifer dominated landscape in relation to two landscape parameters, namely proportion and isolation of suitable habitat. Data from five consecutive spring seasons were used and within habitat variation controlled for. The occurrence of long-tailed tits was positively related to the amount of habitat within 1 km2 (p=0.0007) and negatively related to the distance between habitat patches (p<0.0001). When combined, the two variables explained >78% of the variation in local patch occupancy. There were distinct thresholds in these landscape variables for the probability of local long-tailed tit presence. In the model the probability increased from 0.1 to 0.8 when interpatch distance decreased from 500 to 100 m with 5% total habitat coverage. With a total proportion of 15% suitable habitat, the same probability jump occurred when interpatch distance changed from 900 to 500 m. The general importance of defined measurements and quantified threshold levels for species conservation and landscape management is discussed. 相似文献
8.
Although the area disturbed by linear features in forested systems is small relative to many other human disturbances, linear features create significantly more amounts of edge per unit area. In the boreal plains of Alberta, Canada, energy sector exploration has resulted in extensive dissection of the landscape through 8 m wide seismic lines. A spatially explicit model was developed to test how bird abundance might change in response to increasing seismic line density if individuals use seismic lines as territory boundaries or actively avoid these edges. Assuming birds had fixed territory shape and size, increasing seismic line density from 0 to 8 km/km2 resulted in a 38% decline and an 82% decline in bird abundance when individuals used lines as territory boundaries or avoided edges by 50 m, respectively. We tested the assumptions of our model using the Ovenbird (Seiurus aurocapillus). Based on radio-telemetry (n = 12), all Ovenbirds crossed seismic lines at some point during the breeding season. However, male Ovenbirds showed a distinct use of one side of the seismic line, suggesting lines acted as territory boundaries. In 12.25 ha plots (n = 24) spot-mapping detected no change in Ovenbird density as linear feature density increased from 0 to 8.6 km/km2. In 4 km2 landscapes (n = 62) sampled using a grid of nine point-counts, we also detected no changes in Ovenbird numbers across the same range of seismic line densities. Ovenbirds declined with seismic line density at the level of the individual point-count station (12 ha scale), but only when a threshold seismic line density of 8.5 km/km2 was reached. Above the threshold, Ovenbirds declined 19% for each 1 km/km2 increase in seismic line density. While relatively few places in Alberta’s boreal forest have local seismic line densities of 8.5 km/km2, forest dissection could increasingly become an issue if current energy exploration practices continue. 相似文献
9.
Cultural landscapes of Germany are patch-corridor-matrix mosaics for an invasive megaforb 总被引:1,自引:0,他引:1
Predicting the vulnerability of landscapes to both the initial colonisation and the subsequent spread of invasive species
remains a major challenge. The aim of this study was to assess the relative importance of sub-patch level factors and landscape
factors for the invasion of the megaforb Heracleum mantegazzianum. In particular, we tested which factors affect the presence in suitable habitat patches and the cover-percentage within invaded
patches. For this purpose, we used standard (logistic) regression modelling techniques. The regression analyses were based
on inventories of suitable habitat patches in 20 study areas (each 1 km2) in cultural landscapes of Germany. The cover percentage in invaded patches was independent from landscape factors, except
for patch shape, and even unsatisfactorily explained by sub-patch level factors included in the analysis (R
2 = 0.19). In contrast, presence of H. mantegazzianum was affected by both local and landscape factors. Woody habitat structure decreased the occurrence probability, whereas vicinity
to transport corridors (rivers, roads), high habitat connectivity, patch size and perimeter-area ratio of habitat patches
had positive effects. The significance of corridors and habitat connectivity shows that dispersal of H. mantegazzianum through the landscape matrix is limited. We conclude that cultural landscapes of Germany function as patch-corridor-matrix
mosaics for the spread of H. mantegazzianum. Our results highlight the importance of landscape structure and habitat configuration for invasive spread. Furthermore,
this study shows that both local and landscape factors should be incorporated into spatially explicit models to predict spatiotemporal
dynamics and equilibrium stages of plant invasions. 相似文献
10.
We tested the effects of increased landscape corridor width and corridor presence on the population dynamics and home range use of the meadow vole (Microtus pennsylvanicus) within a small-scale fragmented landscape. Our objective was to observe how populations behaved in patchy landscapes where the animals home range exceeded or equaled patch size. We used a small-scale replicated experiment consisting of three sets of two patches each, unconnected or interconnected by 1-m or 5-m wide-corridors, established in an old-field community (S.W. Ohio). Control (0-m) treatments supported significantly lower vole densities than either corridor treatment. Females were the dominant resident sex establishing smaller home ranges (<150m2) than males (>450m2). Significantly more male voles dispersed between patches with corridors than between patches without corridors. However, no difference was observed regarding the number of male voles dispersing between patches connected by corridors when compared to the number dispersing across treatments. Dispersal between connected patches was restricted to corridors based on tracking tube data. Corridor presence was more important than corridor width regarding the movement of male voles within their home range. 相似文献
11.
To aid effective conservation and management there is a need to understand the effect of landscape on species ecology. The
aim of this research was to assess the effect of landscape parameters on breeding success of barn owls throughout the Rother
and Arun River catchments, Sussex, UK. We used a Geographic Information System to describe the habitat mosaic and landscape
structure within an estimated home range area of 3 km2 around 85 artificial nest box sites. Results showed that land cover was less heterogeneous at successful sites, with home
ranges dominated by a few habitat types of regular patch shapes. Unsuccessful nesting sites had significantly more improved
grassland, suburban land and wetlands than successful sites. Cluster analysis and Principle Components Analysis was used to
assess the similarity of the habitat mosaic within these areas and pellet analysis was undertaken to assess barn owl diet
and prey availability. Ten prey species were recovered from pellets, field vole (Microtus agrestis), common shrews (Sorex araneus) and house mice (Mus musculus) making up nearly 90% of recoveries. However box sites varied in relative proportions of small mammal, and hence prey availability.
Results indicated that land use and landscape structure can affect breeding success in barn owls. Higher levels of poor quality
small mammal habitat were associated with unsuccessful sites. However, at a landscape scale, the habitat mosaic across the
study area lacked variation, limiting analysis and clear correlations between habitat type and positive breeding success,
suggesting that a finer scale was needed in future studies utilising this approach. 相似文献
12.
Movements of bank voles (Clethrionomys glareolus) were studied in a farmland mosaic in Poland. Distances crossed by animals in short-time periods are significantly longer in heterogenous than in homogenous habitats. In long-time and large-spatial scales, a significant portion of the animals in a population travel among habitat elements of the mosaic, reducing the degree of isolation of patch populations and decreasing the probability of local extinction. 相似文献
13.
It is widely accepted that large protected areas are required to effectively conserve historical species composition. However, recent analyses of mammal species loss in Canadian and African national parks contradict earlier conclusions that extent of local extinctions (i.e., extirpations) is strongly inversely related to park size, suggesting that park size alone is inadequate to predict reserve designs that may sustain biodiversity. To plan protected areas that will meet conservation goals, reserve-design models that incorporate other landscape-scale factors in addition to reserve area are needed; potential factors include the types and intensity of land use and habitat change, together with land cover types, in and around parks. Additionally, human population size around parks, and visitor density in parks may affect species loss. We quantified land use, land cover, and human population in and around 24 Canadian national parks to model effects of human disturbance and changes in natural habitats on known mammal extirpations.Multiple regression models were compared using the Akaike Information Criterion (AICc). The most parsimonious model (AICc weighting w
i
= 0.5391) emphasized effective habitat area in and around parks and not visitor numbers nor human population size around parks. Our model suggests that parks with as little as 3140 km2 of effective habitat area inside may be large enough to conserve historical mammal species composition if they are also surrounded by at least 18 000 km2 of effective habitat within 50 km of park boundaries. 相似文献
14.
Linear habitats are becoming increasingly common as a consequence of habitat fragmentation, and may provide the sole habitat
for some species. Hedgerows are linear features that can vary substantially in structure and quality. Having surveyed 180
hedgerows, in four locations, and sampled their small mammal communities we examined the effect of physical hedgerow attributes
on the abundance of small mammal species. Using three elements of landscape structure, we explored whether variation was best
explained by the Random Sample Hypothesis (that small islands represent a random sample of those species populating larger
areas), or by the Fragmentation Hypothesis (that species abundance will decrease with a loss of habitat area). We tested the
relationship between the relative abundance of small mammals and 1. hedgerow connectivity; 2. total habitat availability and
3. local habitat complexity. We then explored the predictive power of combinations of these habitat variables. Connectivity
was a positive predictor of wood mice Apodemus sylvaticus, and hedgerow gappiness was a negative predictor of bank voles Clethrionomys glareolus. The total amount of habitat available (hedgerow width, height and length) was a positive indicator of total small mammal
biomass. These results support the Fragmentation Hypothesis that species abundance and distribution decrease with a loss of
habitat area. The preservation of linear and associated habitats may therefore be important in maintaining metapopulations
of the species we studied. 相似文献
15.
Importance of Wetland Landscape Structure to Shorebirds Wintering in an Agricultural Valley 总被引:2,自引:1,他引:2
Only recently has the influence of landscape structure on habitat use been a research focus in wetland systems. During non-breeding
periods when food can be locally limited, wetland spatial pattern across a landscape may be of great importance in determining
wetland use. We studied the influence of landscape structure on abundances of wintering Dunlin (Calidris alpina) and Killdeer (Charadrius vociferus) observed on wetlands in the agricultural Willamette Valley of Oregon, USA, during two winters (1999–2000, 2000–2001) of
differing rainfall. We examined (1) shorebird use within a sample of 100 km2 regions differing in landscape structure (hectares of shorebird habitat [wet, unvegetated]) and (2) use of sites differing
in landscape context (area of shorebird habitat within a species-defined radius). For use of sites, we also assessed the influence
of two local characteristics: percent of soil exposed and area of wet habitat. We analyzed data using linear regression and
information-theoretic modeling. During the dry winter (2000–2001), Dunlin were attracted to regions with more wetland habitat
and their abundances at sites increased with greater area of shorebird habitat within both the site and the surrounding landscape.
In contrast, Dunlin abundances at sites were related to availability of habitat at only a local scale during the wet winter
(1999–2000). Regional habitat availability was of little importance in predicting Killdeer distributions, and Killdeer site
use appeared unrelated to habitat distributions at both landscape and local scales. Results suggest prioritizing sites for
conservation that are located in areas with high wetland coverage. 相似文献
16.
Jay E. Howell Clinton T. Moore Michael J. Conroy Richard G. Hamrick Robert J. Cooper Reggie E. Thackston John P. Carroll 《Landscape Ecology》2009,24(3):405-418
Large-scale habitat enhancement programs for birds are becoming more widespread, however, most lack monitoring to resolve
uncertainties and enhance program impact over time. Georgia’s Bobwhite Quail Initiative (BQI) is a competitive, proposal-based
system that provides incentives to landowners to establish habitat for northern bobwhites (Colinus virginianus). Using data from monitoring conducted in the program’s first years (1999–2001), we developed alternative hierarchical models
to predict bobwhite abundance in response to program habitat modifications on local and regional scales. Effects of habitat
and habitat management on bobwhite population response varied among geographical scales, but high measurement variability
rendered the specific nature of these scaled effects equivocal. Under some models, BQI had positive impact at both local farm
scales (1, 9 km2), particularly when practice acres were clustered, whereas other credible models indicated that bird response did not depend
on spatial arrangement of practices. Thus, uncertainty about landscape-level effects of management presents a challenge to
program managers who must decide which proposals to accept. We demonstrate that optimal selection decisions can be made despite
this uncertainty and that uncertainty can be reduced over time, with consequent improvement in management efficacy. However,
such an adaptive approach to BQI program implementation would require the reestablishment of monitoring of bobwhite abundance,
an effort for which funding was discontinued in 2002. For landscape-level conservation programs generally, our approach demonstrates
the value in assessing multiple scales of impact of habitat modification programs, and it reveals the utility of addressing
management uncertainty through multiple decision models and system monitoring. 相似文献
17.
In this study, we investigated the environmental factors driving small mammal (rodents and shrews) assemblages in permanent
habitat patches in response to a gradient of agricultural intensification. Small mammals were sampled using a trapping standard
method in the hedgerow networks of three contrasted landscapes differing by their level of land-use intensity and hedgerow
network density (BOC1: slightly intensified; BOC2: moderately intensified and POL: highly intensified). We hypothesized that
habitat and landscape characteristics have to be considered to understand the structure of local community. In that way, we
carried out a multi-scale study using environmental variables ranging from local habitat (structure and composition of the
hedgerows) to hedgerows neighbourhoods in a radius of 300 m (land cover and connectivity around hedges) and to landscape units
(three sites). During 1 year, 24 hedgerows were sampled seven times, representing a total of 1,379 captures (86% of rodents
and 14% of shrews) and eight species, dominated by the wood mouse (Apodemus sylvaticus) and the bank vole (Clethrionomys glareolus). Inter-site variability was significant and accounted for 18% of total variation in small mammal species abundances. But
intra-site variability was also highlighted: species abundance profiles may differ greatly among hedgerows within a site.
The more explanatory variables were identified at the different scales of the study: the landscape unit POL was shown to be
an important factor in structuring the community, but the predominant factors explaining differences of abundances among hedgerows
were about local habitat. In fact, the width of hedges and the tree species richness appeared to be significant and explaining
the greatest part of the total variation of the small mammal community composition. 相似文献
18.
Wayne C. Zipperer 《Landscape Ecology》1993,8(3):177-184
Five identifiable patterns of deforestation are recognized - internal, indentation, cropping, fragmentation, and removal - and each has a distinct effect on habitat quality of forest patches in the eastern United States. By overlaying land use maps from 1973 and 1981 for three counties in the State of Maryland (Prince Georges, Anne Arundel, and Wicomico), changes in the interior core area and edge length of individual patches were measured. Forest interior declined by 23.8 km2 in Anne Arundel, 16.3 km2 in Prince Georges, and 8.4 km2 in Wicomico. Within Anne Arundel and Prince Georges Counties, deforestation increased edge length by 52.1 km and 31.2 km, respectively, whereas, within Wicomico, it decreased edge length by 8.7 km. Differences among counties resulted from current land use patterns, percentage of forest cover, and the dominant deforestation pattern. 相似文献
19.
Small mammal and raptor densities in habitat islands; area effects in a south Swedish agricultural landscape 总被引:1,自引:0,他引:1
Jon Loman 《Landscape Ecology》1991,5(3):183-189
There was no significant correlation between the size of habitat islands in cropped fields and the density of field vole, bank vole, and common shrew populations during autumn. Despite this, winter densities of perching raptors were considerably higher in small islands than in large one. Explanations for this, apparently suboptimal, hunting pattern are discussed. The distribution should increase predation mortality for small rodents in small compared to large patches and may have been the cause of the higher winter mortality actually found for field voles in small patches. 相似文献
20.
A comprehensive understanding of variables associated with spatial differences in community composition is essential to explain
and predict biodiversity over landscape scales. In this study, spatial patterns of bird diversity in Central Kalimantan, Indonesia,
were examined and associated with local-scale (habitat structure and heterogeneity) and landscape-scale (logging, slope position
and elevation) environmental variables. Within the study area (c. 196 km2) local habitat structure and heterogeneity varied considerably, largely due to logging. In total 9747 individuals of 177
bird species were recorded. Akaike's information criterion (AIC) revealed that the best explanatory models of bird community
similarity and species richness included both local- and landscape-scale environmental variables. Important local-scale variables
included liana abundance, fern cover, sapling density, tree density, dead wood abundance and tree architecture, while important
landscape-scale variables were elevation, logging and slope position. Geographic distance between sampling sites was not significantly
associated with spatial variation in either species richness or similarity. These results indicate that deterministic environmental
processes, as opposed to dispersal-driven stochastic processes, primarily structure bird assemblages within the spatial scale
of this study and confirm that highly variable local habitat measures can be effective means of predicting landscape-scale
community patterns. 相似文献