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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.
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
3.
Metapopulation models are frequently used for analysing species–landscape interactions and their effect on structure and dynamic
of populations in fragmented landscapes. They especially support a better understanding of the viability of metapopulations.
In such models, the processes determining metapopulation viability are often modelled in a simple way. Animals’ dispersal
between habitat fragments is mostly taken into account by using a simple dispersal function that assumes the underlying process
of dispersal to be random movement. Species-specific dispersal behaviour such as a systematic search for habitat patches is
likely to influence the viability of a metapopulation. Using a model for metapopulation viability analysis, we investigate
whether such specific dispersal behaviour affects the predictions of ranking orders among alternative landscape configurations
rated regarding their ability to carry viable metapopulations. To incorporate dispersal behaviour in the model, we use a submodel
for the colonisation rates which allows different movement patterns to be considered (uncorrelated random walk, correlated
random walk with various degrees of correlation, and loops). For each movement pattern, the landscape order is determined
by comparing the resulting mean metapopulation lifetime Tm of different landscape configurations. Results show that landscape orders can change considerably between different movement
patterns. We analyse whether and under what circumstances dispersal behaviour influences the ranking orders of landscapes.
We find that the ‘competition between patches for migrants’ – i.e. the fact that dispersers immigrating into one patch are
not longer available as colonisers for other patches – is an important factor driving the change in landscape ranks. The implications
of our results for metapopulation modelling, planning and conservation are discussed. 相似文献
4.
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
5.
The viability of metapopulations in fragmented landscapes has become a central theme in conservation biology. Landscape fragmentation
is increasingly recognized as a dynamical process: in many situations, the quality of local habitats must be expected to undergo
continual changes. Here we assess the implications of such recurrent local disturbances for the equilibrium density of metapopulations.
Using a spatially explicit lattice model in which the considered metapopulation as well as the underlying landscape pattern
change dynamically, we show that equilibrium metapopulation density is maximized at intermediate frequencies of local landscape
disturbance. On both sides around this maximum, the metapopulation may go extinct. We show how the position and shape of the
intermediate viability maximum is responding to changes in the landscape’s overall habitat quality and the population’s propensity
for local extinction. We interpret our findings in terms of a dual effect of intensified landscape disturbances, which on
the one hand exterminate local populations and on the other hand enhance a metapopulation’s capacity for spreading between
habitat clusters. 相似文献
6.
Habitat fragmentation, patch quality and landscape structure are important predictors for species richness. However, conservation
strategies targeting single species mainly focus on habitat patches and neglect possible effects of the surrounding landscape.
This project assesses the impact of management, habitat fragmentation and landscape structure at different spatial scales
on the distribution of three endangered butterfly species, Boloria selene, Boloria titania and Brenthis ino. We selected 36 study sites in the Swiss Alps differing in (1) the proportion of suitable habitat (i.e., wetlands); (2) the
proportion of potential dispersal barriers (forest) in the surrounding landscape; (3) altitude; (4) habitat area and (5) management
(mowing versus grazing). Three surveys per study site were conducted during the adult flight period to estimate occurrence
and density of each species. For the best disperser B. selene the probability of occurrence was positively related to increasing proportion of wetland on a large spatial scale (radius:
4,000 m), for the medium disperser B. ino on an intermediate spatial scale (2,000 m) and for the poorest disperser B. titania on a small spatial scale (1,000 m). Nearby forest did not negatively affect butterfly species distribution but instead enhanced
the probability of occurrence and the population density of B. titania. The fen-specialist B. selene had a higher probability of occurrence and higher population densities on grazed compared to mown fens. The altitude of the
habitat patches affected the occurrence of the three species and increasing habitat area enhanced the probability of occurrence
of B. selene and B. ino. We conclude that, the surrounding landscape is of relevance for species distribution, but management and habitat fragmentation
are often more important. We suggest that butterfly conservation should not focus only on a patch scale, but also on a landscape
scale, taking into account species-specific dispersal abilities. 相似文献
7.
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
8.
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
9.
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
10.
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
11.
Birger Hörnfeldt Pernilla Christensen Per Sandström Frauke Ecke 《Landscape Ecology》2006,21(7):1135-1150
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). We monitored this decline by snap-trapping on 58 permanent plots spread over 100 km2 in spring and fall from fall 1971–2003. The reason for the decline is largely unknown, although a common major factor is
likely to be involved in the decline of C. rufocanus and of the coexisting voles. However, here we deal with the reasonability of one complementary hypothesis, the habitat fragmentation
hypothesis, which assumes that part of the decline of C. rufocanus is caused by habitat (forest) destruction. There was considerable local variation in the decline among the 58 1-ha sampling
plots, with respect to both density and timing of the decline; however, all declines ended up with local extinction almost
without exception. Local declines were not associated with habitat destruction by clear-cutting within sampling-plots, as
declines started about equally often before as after clear-cutting, which suggested that habitat destruction outside sampling
plots could be involved. In a multiple regression analysis, local habitat preference (LHP; expressed as a ratio of observed
to expected number of voles trapped per habitat) together with two habitat variables in the surrounding (2.5×2.5 km2) landscape matrix explained 56% of the variation among local cumulated densities of C. rufocanus and hence of local time-series. LHP was positively correlated and explained 31% of the variation, while connectivity among
clear-cuts was negatively correlated and proximity among xeric-mesic mires was positively correlated and explained additional
16% and 9%, respectively. Even if the overall decline cannot be connected to local clear-cutting on sampling-plots, clear-cutting
and hence habitat fragmentation/destruction in the surrounding landscapes potentially influenced grey-sided vole numbers negatively. 相似文献
12.
Paige M. Schmidt Robert A. McCleery Roel R. Lopez Nova J. Silvy Jason A. Schmidt Neil D. Perry 《Landscape Ecology》2011,26(10):1419-1431
Degradation of coastal systems has led to increased impacts from hurricanes and storm surges and is of concern for coastal
endemics species. Understanding the influence of disturbance on coastal populations like the endangered Lower Keys marsh rabbit
(Sylvilagus palustris hefneri) is important to understanding long-term dynamics and for recovery planning. We evaluated the effect of disturbance on the
rabbits by determining which patch, habitat, and landscape characteristics influenced habitat use following Hurricane Wilma.
We determined patch-level occurrence 6–9 months prior to Hurricane Wilma, within 6 months following the hurricane, and 2 years
after the storm to quantify rates of patch abandonment and recurrence. We observed high patch abandonment (37.5% of used patches)
6 months after Hurricane Wilma and low rates of recurrence (38.1% of abandoned patches) 2 years after the storm, an indication
that this storm further threatened marsh rabbit viability. We found the proportion of salt-tolerant (e.g., mangroves and scrub
mangroves) and salt-intolerant (e.g., freshwater wetlands) vegetation within LKMR patches were negatively and positively correlated
with probability of patch abandonment, respectively. We found patch size and the number of used patches surrounding abandoned
patches were positively correlated with probability of recurrence. We suggest habitat use following this hurricane was driven
by the differential response of non-primary habitats to saline overwash and habitat loss from past development that reduced
the size and number of local populations. Our findings demonstrate habitat use studies should be conducted following disturbance
and should incorporate on-going effects of development and climate change. 相似文献
13.
14.
Marleen M. P. Cobben Jana Verboom Paul F. M. Opdam Rolf F. Hoekstra René Jochem Marinus J. M. Smulders 《Landscape Ecology》2012,27(2):227-237
In response to climate change a species may move, adapt, or go extinct. For the adaptability of a population its genetic diversity
is essential, but climate change-induced range shifts can cause a loss of genetic diversity. We investigated how landscape
structure affects the level and distribution of genetic diversity in metapopulations subject to climate change-induced range
shifts. For this we used the spatially explicit, individual-based model METAPHOR which simulates metapopulation demography
and genetics under different temperature increase scenarios. The results indicated that increasing total habitat area may
enhance the maintenance of the genetic diversity in metapopulations while they are shifting their range under climate change.
However, the results also showed that a high level of total habitat area did not prevent the populations in the newly colonised
habitat area of being depleted of much of the original genetic diversity. We therefore conclude that enhancing landscape connectivity
may lead to a delayed loss of genetic diversity in metapopulations under climate change, but that additional measures would
be necessary to ensure its long-term conservation. Importantly, our simulations also show that a landscape which could be
regarded as well-structured under stable climatic conditions, may be inferior for the conservation of genetic diversity during
a range shift. This is important information for landscape management when developing strategies for the in situ conservation
of genetic variation in natural populations under climate change. 相似文献
15.
Megan J. Brady Clive A. McAlpine Craig J. Miller Hugh P. Possingham Greg S. Baxter 《Landscape Ecology》2009,24(7):879-891
The matrix is an important element of landscape mosaics that influences wildlife indirectly through its influence on habitat,
and directly, if they live in or move through it. Therefore, to quantify and manage habitat quality for wildlife in modified
landscapes, it is necessary to consider the characteristics of both patch and matrix elements of the whole landscape mosaic.
To isolate matrix effects from the often simultaneous and confounding influence of patch and landscape characteristics, we
identified nineteen 500 m radius landscapes in southeast Queensland, Australia with similar remnant forest patch attributes,
habitat loss, and fragmentation, but exhibiting a marked gradient from rural through high-density suburban development of
the matrix, quantified by a weighted road-length metric. We measured habitat disturbance, structure, and floristics in patch
core, patch edge and matrix landscape elements to characterise how landscape habitat quality changes for small mammals. Correlation
analyses identified that with increased matrix development intensity, human disturbance of core sites increased, predators
and exotic plant species richness in matrix sites increased, and structural complexity (e.g. logs and stumps) in the matrix
decreased. Ordination analyses showed landscape elements were most similar in habitat structure and floristics at low to moderate
levels of matrix development, suggesting enhanced landscape habitat quality. Matrix development intensity was not, however,
the greatest source of overall variation of habitat throughout landscapes. Many variables, such as landholder behaviour, complicate
the relationship. For enhanced conservation outcomes the matrix needs to be managed to control disturbances and strategically
plan for matrix habitat retention and restoration. 相似文献
16.
The understanding and prediction of the responses of animal populations to habitat fragmentation is a central issue in applied
ecology. The identification of habitat variables associated to patch occupancy is particularly important when habitat quality
is affected by human activities. Here, we analyze the influence of patch and landscape characteristics on patch occupancy
by the subterranean herbivorous rodent Ctenomys porteousi. Patch occupancy was monitored in a network of 63 habitat patches identified by satellite imagery analysis which extends
along almost the whole distributional range for C. porteousi. Suitable habitat for the occurrence of C. porteousi is highly fragmented and represents <10% of the total area in its distributional range. The distribution of C. porteousi in the patch network is affected not only by characteristics of the habitat patches, but also by those of the surrounding
landscape matrix. Significant differences between occupied and empty patches were found in several environmental variables.
Overall, occupied patches were larger, less vegetated, more connected, and had larger neighbor patches than empty patches.
A stepwise procedure on a generalized linear model selected four habitat variables that explain patch occupancy in C. porteousi; it included the effects of habitat quality in the matrix surrounding the patch, average vegetation cover in the patch, minimum
vegetation cover in the matrix surrounding the patch, and the area of the nearest neighbor patch. These results indicate that
patch occupancy in C. porteousi is strongly influenced by the availability and quality of habitat both in the patch and in the surrounding landscape matrix. 相似文献
17.
The distribution and abundance of a species may be simultaneously influenced by both local-scale habitat features and the
broader patch and landscape contexts in which these populations occur. Different factors may influence patch occupancy (presence–absence)
versus local abundance (number of individuals within patches), and at different scales, and thus ideally both occupancy and
abundance should be investigated, especially in studies that seek to understand the consequences of land management on species
persistence. Our study evaluated the relative influences of variables associated with the local habitat patch, hillside (patch
context), and landscape context on patch occupancy and abundance of the collared lizard (Crotaphytus collaris) within tallgrass prairie managed under different fire and grazing regimes in the northern Flint Hills of Kansas, USA. Using
a multi-model information-theoretic approach that accounted for detection bias, we found that collared lizard abundance and
occupancy was influenced by factors measured at both the local habitat and landscape scales. At a local scale, collared lizard
abundance was greatest on large rock ledges that had lots of crevices, high vegetation complexity, and were located higher
up on the hillslope. At the landscape scale, collared lizard abundance and occupancy were both higher in watersheds that were
burned frequently (1–2 year intervals). Interestingly, grazing only had a significant effect on occupancy and abundance within
less frequently burned (4-year burn interval) watersheds. Our results suggest that, in addition to the obvious habitat needs
of this species (availability of suitable rock habitat), land-management practices have the potential to influence collared
lizard presence and abundance in the grasslands of the Flint Hills. Thus, mapping the availability of suitable habitat is
unlikely to be sufficient for evaluating species distributions and persistence in such cases without consideration of landscape
management and disturbance history. 相似文献
18.
Spatial dynamics of the knob-tailed gecko Nephrurus stellatus in a fragmented agricultural landscape
In fragmented landscapes, a species?? dispersal ability and response to habitat condition are key determinants of persistence. To understand the relative importance of dispersal and condition for survival of Nephrurus stellatus (Gekkonidae) in southern Australia, we surveyed 92 woodland remnants three times. This gecko favours early post-fire succession conditions so may be at risk of extinction in the long-unburnt agricultural landscape. Using N-mixture models, we compared the influence of four measures of isolation, patch area and two habitat variables on the abundance and occurrence of N. stellatus, while taking into account detection probability. Patch occupancy was high, despite the long-term absence of fire from most remnants. Distance to the nearest occupied site was the most informative measure of patch isolation, exhibiting a negative relationship with occupancy. Distance to a nearby conservation park had little influence, suggesting that mainland?Cisland metapopulation dynamics are not important. Abundance and occurrence were positively related to ?%-cover of spinifex (Triodia), indicating that niche-related factors may also contribute to spatial dynamics. Patterns of patch occupancy imply that N. stellatus has a sequence of spatial dynamics across an isolation gradient, with patchy populations and source-sink dynamics when patches are within 300?m, metapopulations at intermediate isolation, and declining populations when patches are separated by >1?C2?km. Considering the conservation needs of the community, habitat condition and connectivity may need to be improved before fire can be reintroduced to the landscape. We speculate that fire may interact with habitat degradation and isolation, increasing the risk of local extinctions. 相似文献
19.
Forest bird species exhibit noticeable seasonal behavioral changes that might lead to contrasting effects of landscape pattern
upon species abundance and performance. We assessed if the effect of patch and habitat attributes on the landscape use of
thorn-tailed rayaditos (Aphrastura spinicauda), a forest bird in a relict patchy forest in northern Chile, varied temporally in association with changes in the behavior
of individuals linked to breeding vs. non-breeding conditions. We also assessed the relationship between nest success and
patch and habitat attributes, as nest success might be associated to the density rayaditos during the breeding season. We
found that density of rayaditos was affected by patch size and functional connectivity but not by habitat structure and that
the magnitude of the effect of patch size was greater during the non-breeding season, thus supporting the existence of a temporally
variable effect of landscape pattern. Similarly, the nest success of rayaditos was positively affected by functional connectivity
and negatively by structural connectivity. We hypothesize that these results emerged from the interaction among territorial
behavior, resource limitation and predation risk. Despite the variable intensity of the effect of patch size upon density,
however, this landscape attribute, in addition to connectivity, is essential for the persistence of rayaditos at this relict
patchy forest landscapes. 相似文献
20.
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