共查询到20条相似文献，搜索用时 31 毫秒
1.
Rebecca Lange Tim Diekötter Lisa A. Schiffmann Volkmar Wolters Walter Durka 《Landscape Ecology》2012,27(3):381-392
Unlike rare or specialised species, widespread abundant species have often been neglected when studying effects of habitat
fragmentation. However, recently, it was shown that in the widespread abundant bush cricket Pholidoptera griseoaptera gene flow becomes restricted when the share of suitable habitat dropped below a threshold of 20% at the landscape scale.
Here, using the same highly fragmented landscape, we studied the impact of habitat configuration and matrix quality on genetic
variation and population differentiation of P. griseoaptera at a small spatial scale. We investigated four clusters of three populations that were either disconnected or connected and
had either low quality (arable land) or high quality (grassland) matrix. The number of alleles was significantly lower in
disconnected than in connected clusters, irrespective of matrix quality. Genetic differentiation was equally high in the two
disconnected clusters and in the connected cluster with low quality matrix (G
ST ≥ 0.030; D ≥ 0.082), whereas it was significantly reduced when connected habitats were embedded in a high quality grassland matrix (G
ST = 0.004; D = 0.011). Analyses of least-cost paths showed that grassy landscape elements in fact represent high quality matrix, but that
linear grassy margins are costly for dispersal. The effect of habitat configuration on genetic diversity may be explained
by lower effective population sizes in disconnected habitats. The fact that only the connected populations in high quality
matrix were not differentiated indicates that landscape management should simultaneously consider habitat configuration and
matrix quality to effectively promote small and dispersal-limited species, also at small spatial scales. 相似文献
2.
Individual movement is a key process affecting the distribution of animals in heterogeneous landscapes. For specialist species in patchy habitat, a central issue is how dispersal distances are related to landscape structure. We compared dispersal distances for cactus bugs (Chelinidea vittiger) on two naturally fragmented landscapes (≤ 4% suitable habitat) with different matrix structures (i.e., vegetation height of nonsuitable habitat between suitable patches). Using mark-release-recapture studies, we determined that most transfers between cactus patches occurred during the mating season. Dispersal distances were reduced by > 50% on the landscape that had reduced structural connectivity due to relatively high matrix structure and low patch density. An experiment with detailed movement pathways demonstrated that greater matrix structure decreased mean step lengths, reduced directionality, and thus decreased net displacement by > 60%. However, habitat edges between two matrix elements that differed substantially in resistance to movement were completely permeable. Therefore, the difference in distributions of dispersal distances between the two landscapes mainly reflected the average resistance of matrix habitat and not the level of matrix heterogeneity per se. Our study highlights the merits of combining estimates of dispersal distances with insights on mechanisms from detailed movement pathways, and emphasizes the difficulty of treating dispersal distances of species as fixed traits independent of landscape structure. 相似文献
3.
Anne M. Trainor Jeffrey R. Walters William F. Morris Joseph Sexton Aaron Moody 《Landscape Ecology》2013,28(4):755-767
Persistence of wildlife populations depends on the degree to which landscape features facilitate animal movements between isolated habitat patches. Due to limited data availability, the effect of landscape features on animal dispersal is typically estimated using expert opinion. With sufficient data, however, resistance surfaces can be estimated empirically. After modeling suitable prospecting habitat using an extensive dataset from the federally endangered red-cockaded woodpecker (Picoides borealis), we used data from over 800 prospecting events from 34 radio-tagged birds to identify the best relationship between habitat suitability and resistance surfaces. Our results demonstrated that juvenile female P. borealis prospecting for new territories beyond their natal territories preferred to traverse through forests with tall canopy and minimal midstory vegetation. The non-linear relationship between habitat suitability and resistance surfaces was the most biologically relevant transformation, which in turn identified the specific forest composition that promoted and inhibited prospecting and dispersal behavior. These results corresponded with over 60 % of dispersal events from an independent dataset of short-distance dispersal events. This new understanding of P. borealis prospecting behavior will help to identify areas necessary for maintaining habitat connectivity and to implement effective management strategies. Our approach also provides a framework to not only estimate and evaluate resistance surfaces based on species-specific responses to intervening landscape features, but also addresses an often-neglected step, selecting a biologically relevant function to transform habitat suitability model into a resistance surface. 相似文献
4.
Piotr Nowicki Vladimir Vrabec Birgit Binzenhöfer Johann Feil Barbara Zakšek Thomas Hovestadt Josef Settele 《Landscape Ecology》2014,29(3):401-412
Metapopulation models typically assume that suitable habitats occupied by local populations and unsuitable matrix separating them form a ‘black-and-white’ landscape mosaic, in which dispersal is primarily determined by the spatial configuration of habitat patches. In reality, however, the matrix composition is also likely to influence dispersal. Using intensive mark-recapture surveys we investigated inter-patch movements in Maculinea (Phengaris) nausithous and M. teleius occurring sympatrically in six metapopulations. Three of these metapopulations had the matrix dominated by forest, an inhospitable environment for grassland butterflies, whereas in the remaining three the matrix was mostly composed of open environments. Dispersal parameters derived with the Virtual Migration model revealed significant differences between both groups of metapopulations. Both species had a lower propensity to emigrate from their natal habitat patches, and they suffered substantially higher dispersal mortality in the metapopulations with forest matrix. On the other hand, mean dispersal distances were roughly an order of magnitude longer in forest matrix as compared with open landscapes (ca. 500–1,500 vs. 100–200 m). Our results suggest that inhospitable forest matrix induces strong selection against dispersal, leading to a reduced emigration rate. At the same time, the selection may promote emigrants with good dispersal abilities, which are able to perform long-distance movements. Thus, while it is generally believed that a matrix structurally similar to the habitat of a species should improve the functional connectivity of habitat patches, our findings imply that this may not necessarily be the case. 相似文献
5.
This study investigated the efficacy of linear landscape elements in fragmented landscapes as corridors for perennial grassland
species with short-range seed dispersal. Corridors are assumed to be essential for the persistence of metapopulations in fragmented
landscapes, but it is unclear to what extent linear landscape elements such as ditch banks and road verges can function as
corridors for those species. The principal factors that determine the rate of migration through corridors include the width
and habitat quality of patches within a corridor (expressed as the population growth rate λ) and the dispersal capacity of
plants (expressed as the slope α of the relationship between seed number and log-distance).
A cellular automation model was used to simulate the effects of the principal factors on the rate of migration. Simulations
with different levels of the principal factors showed highly significant and positive main effects of dispersal capacity,
habitat quality and width of corridors on the migration rate. Significant interactions existed between dispersal capacity
× width and dispersal capacity × habitat quality (p<0.0001), indicating that the effects of width and habitat quality depended
on the dispersal capacity. In narrow corridors most of the dispersed seeds were deposited outside the corridor, which significantly
reduced migration rates, especially for species with long-range dispersal (α=−0.4). In wide corridors (up to 20 m), seed losses
were much smaller and migration rates approximated those of continuous habitats. The contribution of the few long-range seeds
to the rate of migration was significant when habitat quality was high (population growth rates up to 2.5). However, in all
simulations migration rates were very low,i.e.<5 m/yr.
It is concluded that linear landscape elements are not effective corridors in fragmented landscapes for plants with short-range
seed dispersal, because migration rates are low (<5 m/yr), landscape elements vary in the percentage of high quality patches,
and refugia and suitable habitat patches are frequently several kilometres apart, making a cohesive infrastructure of corridors
for plants elusive. It is argued that the best way to conserve endangered plant species that encounter dispersal barriers
is to harvest seeds from nearby source populations and introduce them as suitable habitats. 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.
Petra Janečková Štěpán Janeček Jitka Klimešová Lars Götzenberger Jan Horník Jan Lepš Francesco de Bello 《Landscape Ecology》2017,32(4):791-805
Context
Landscape fragmentation significantly affects species distributions by decreasing the number and connectivity of suitable patches. While researchers have hypothesized that species functional traits could help in predicting species distribution in a landscape, predictions should depend on the type of patches available and on the ability of species to disperse and grow there.Objectives
To explore whether different traits can explain the frequency of grassland species (number of occupied patches) and/or their occupancy (ratio of occupied to suitable patches) across a variety of patch types within a fragmented landscape.Methods
We sampled species distributions over 1300 grassland patches in a fragmented landscape of 385 km2 in the Czech Republic. Relationships between functional traits and species frequency and occupancy were tested across all patches in the landscape, as well as within patches that shared similar management, wetness, and isolation.Results
Although some traits predicting species frequency also predicted occupancy, others were markedly different, with competition- and dispersal-related traits becoming more important for occupancy. Which traits were important differed for frequency and occupancy and also differed depending on patch management, wetness, and isolation.Conclusions
Plant traits can provide insight into plant distribution in fragmented landscapes and can reveal specific abiotic, biotic, and dispersal processes affecting species occurrence in a patch type. However, the importance of individual traits depends on the type of suitable patches available within the landscape.8.
Renato Crouzeilles Jayme Augusto Prevedello Marcos de Souza Lima Figueiredo Maria Lucia Lorini Carlos Eduardo Viveiros Grelle 《Landscape Ecology》2014,29(3):479-489
Habitat availability—or how much habitat species can reach at the landscape scale—depends primarily on the percentage of native cover. However, attributes of landscape configuration such as the number, size and isolation of habitat patches may have complementary effects on habitat availability, with implications for the management of landscapes. Here, we determined whether, and at which percentages of native cover, the number, size and isolation of patches contribute for habitat availability. We quantified habitat availability in 325 landscapes spread across the state of Rio de Janeiro, in the Atlantic Forest hotspot, with either high (>50 %), intermediate (50–30 %), low (30–10 %) or very low (<10 %) percentage of native cover, and for six hypothetical species differing in inter-patch dispersal ability. Above 50 % of native cover, the percentage of cover per se was the only determinant of habitat availability, but below 50 % the attributes of landscape configuration also contributed for habitat availability. The number of patches had a negative effect on habitat availability in landscapes with 50–10 % of native cover, whereas patch size had a positive effect in landscapes with <10 % of native cover. The different species generally responded to the same set of landscape attributes, although to different extents, potentially facilitating decision making for conservation. In landscapes with >50 % of native cover, conservation actions are probably sufficient to guarantee habitat availability, whereas in the remaining landscapes additional restoration efforts are needed, especially to reconnect and/or enlarge remaining habitat patches. 相似文献
9.
Michael C. Wimberly 《Landscape Ecology》2006,21(1):35-46
Although landscape ecology emphasizes the effects of spatial pattern on ecological processes, most neutral models of species–habitat relationships have treated habitat as a static constraint. Do the working hypotheses derived from these models extend to real landscapes where disturbances create a shifting mosaic? A spatial landscape simulator incorporating vegetation dynamics and a metapopulation model was used to compare species in static and dynamic landscapes with identical habitat amounts and spatial patterns. The main drivers of vegetation dynamics were stand-replacing disturbances, followed by gradual change from early-successional to old-growth habitats. Species dynamics were based on a simple occupancy model, with dispersal simulated as a random walk. As the proportion of available habitat (p) decreased from 1.0, species occupancy generally declined more rapidly and reached extinction at higher habitat levels in dynamic than in static landscapes. However, habitat occupancy was sometimes actually higher in dynamic landscapes than in static landscapes with similar habitat amounts and patterns. This effect was most pronounced at intermediate amounts of habitat (p = 0.3?0.6) for mobile species that had high colonization rates, but were unable to cross non-habitat patches. Differences between static and dynamic landscapes were contingent upon the initial metapopulation size and the shapes of disturbances and the resulting habitat patterns. Overall, the results demonstrate that dispersal-limited species exhibit more pronounced critical behavior in dynamic landscapes than is predicted by simple neutral models based on static landscapes. Thus, caution should be exercised in extending generalizations derived from static landscape models to disturbance-driven landscape mosaics. 相似文献
10.
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
11.
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
12.
Anne Villemey William E. Peterman Murielle Richard Annie Ouin Inge van Halder Virginie M. Stevens Michel Baguette Philip Roche Frédéric Archaux 《Landscape Ecology》2016,31(7):1629-1641
Context
Anthropogenic activities readily result in the fragmentation of habitats such that species persistence increasingly depends on their ability to disperse. However, landscape features that enhance or limit individual dispersal are often poorly understood. Landscape genetics has recently provided innovative solutions to evaluate landscape resistance to dispersal.Objectives
We studied the dispersal of the common meadow brown butterfly, Maniola jurtina, in agricultural landscapes, using a replicated study design and rigorous statistical analyses. Based on existing behavioral and life history research, we hypothesized that the meadow brown would preferentially disperse through its preferred grassy habitats (meadows and road verges) and avoid dispersing through woodlands and the agricultural matrix.Methods
Samples were collected in 18 study landscapes of 5 × 5 km in three contrasting agricultural French regions. Using circuit theory, least cost path and transect-based methods, we analyzed the effect of the landscape on gene flow separately for each sex.Results
Analysis of 1681 samples with 6 microsatellites loci revealed that landscape features weakly influence meadow brown butterfly gene flow. Gene flow in both sexes appeared to be weakly limited by forests and arable lands, whereas grasslands and grassy linear elements (road verges) were more likely to enhance gene flow.Conclusion
Our results are consistent with the hypothesis of greater dispersal through landscape elements that are most similar to suitable habitat. Our spatially replicated landscape genetics study allowed us to detect subtle landscape effects on butterfly gene flow, and these findings were reinforced by consistent results across analytical methods.13.
14.
Ferenc Jordán Tibor Magura Béla Tóthmérész Vera Vasas Viktor Ködöböcz 《Landscape Ecology》2007,22(10):1527-1539
For many species, one important key to persistence is maintaining connectivity among local populations that allow for dispersal
and gene flow. This is probably true for carabid species (Coleoptera:Carabidae) living in the fragmented forests of the Bereg
Plain (NE Hungary and W Ukraine). Based on field data, we have drafted a landscape graph of the area representing the habitat
network of these species. Graph nodes and links represented two kinds of landscape elements: habitat (forest) patches and
corridors, respectively. The quality of habitat patches and corridors were ranked (from low (1) to high (4)), reflecting local
population sizes in the case of patches and estimated permeability in the case of corridors. We analysed (1) the positional
importance of landscape elements in maintaining the connectivity of the intact network, (2) the effect of inserting hypothetical
corridors into the network, (3) the effects of improving the quality of the existing corridors, and (4) how to connect every
patch in a cost-effective way. Our results set quantitative priorities for conservation practice by identifying important
corridors: what to protect, what to build and what to improve. Several network analytical techniques were used to account
for the directed (source-sink) and highly fragmented nature of the landscape graph. We provide conservation priority ranks
for the landscape elements and discuss the conditions for the use of particular network indices. Our study could be of extreme
relevance, since a new highway is being planned through the area. 相似文献
15.
Graph-based analysis is a promising approach for analyzing the functional and structural connectivity of landscapes. In human-shaped
landscapes, species have become vulnerable to land degradation and connectivity loss between habitat patches. Movement across
the landscape is a key process for species survival that needs to be further investigated for heterogeneous human-dominated
landscapes. The common frog (Rana temporaria) was used as a case study to explore and provide a graph connectivity analysis framework that integrates habitat suitability
and dispersal responses to landscape permeability. The main habitat patches influencing habitat availability and connectivity
were highlighted by using the software Conefor Sensinode 2.2. One of the main advantages of the presented graph-theoretical
approach is its ability to provide a large choice of variables to be used based on the study’s assumptions and knowledge about
target species. Based on dispersal simulation modelling in potential suitable habitat corridors, three distinct patterns of
nodes connections of differing importance were revealed. These patterns are locally influenced by anthropogenic barriers,
landscape permeability, and habitat suitability. And they are affected by different suitability and availability gradients
to maximize the best possible settlement by the common frog within a terrestrial habitat continuum. The study determined the
key role of landscape-based approaches for identifying the “availability-suitability-connectivity” patterns from a local to
regional approach to provide an operational tool for landscape planning. 相似文献
16.
Landscape ecologists have increasingly turned to the use of landscape graphs in which a landscape is represented as a set of nodes (habitat patches) connected by links representing inter-patch-dispersal. This study explores the use of a graph-based regionalization method, Graph-based REgionalization with Clustering And Partitioning (GraphRECAP), to detect structural groups of habitat patches (compartments) in a landscape graph such that the connections (i.e. the movement of individual organisms) within the groups are greater than those across groups. Specifically, we mapped compartments using habitat and dispersal data for ring-tailed lemurs (Lemur catta) in an agricultural landscape in southern Madagascar using both GraphRECAP and the widely-used Girvan and Newman method. Model performance was evaluated by comparing compartment characteristics and three measures of network connectivity and traversability: the connection strength of habitat patches in the compartments (modularity), the potential ease of individual organism movements (Harary index), and the degree of alternative route presence (Alpha index). Compartments identified by GraphRECAP had stronger within-compartment connections, greater traversability, more alternative routes, and a larger minimum number of habitat patches within compartments, all of which are more desirable traits for ecological networks. Our method could thus facilitate the study of ecosystem resilience and the design of nature reserves and landscape networks to promote the landscape-scale dispersal of species in the fragmented habitats. 相似文献
17.
We extend the recently proposed graph-theoretical landscape perspective by applying some network-centric methods mainly developed
in the social sciences. The methods we propose are suitable to (1) identify individual habitat patches that are disproportionally
high in importance in preserving the ability of organisms to traverse the fragmented landscape, and (2) find internally well-connected
compartments of habitat patches that contribute to a spatial compartmentalization of species populations. We demonstrate the
utility of these methods using an agricultural landscape with scattered dry-forest patches in southern Madagascar, inhabited
by the ring-tailed lemur, Lemur catta. We suggest that these methods are particularly suitable in landscapes where species’ traversability is not fully inhibited
by fragmentation, but merely limited. These methods are potentially highly relevant in studying spatial aspects of resilience
and in the design of natural reserves. 相似文献
18.
Steven Walters 《Landscape Ecology》2007,22(6):867-881
Understanding the impacts of habitat fragmentation on dispersal is an important issue in landscape and conservation ecology.
Here I examine the effects of fine- to broad-scale patterns in landscape structure on dispersal success of organisms with
differing life-history traits. An individual-based model was used to simulate dispersal of amphibian-like species whose movements
were driven by land cover and moisture conditions. To systematically control spatial pattern, a landscape model was created
by merging simulated land cover maps with synthetic topographic surfaces. Landscapes varied in topographic roughness and spatial
contagion in agriculture and urban land cover. Simulations included three different species types that varied in their maximum
potential dispersal distances by 1-, 2-, or 4-fold. Two sets of simulations addressed effects of varying aspects of landscape
structure on dispersal success. In the first set of simulations, which incorporated variable distances between breeding patches,
dispersal success was lowest for all species types when anthropogenic cover was patchily distributed. In the second set, with
interpatch distances held constant as landscape composition varied, dispersal success decreased as anthropogenic cover became
spatially contagious. Both sets revealed strong main effects of species characteristics, interpatch distances and landscape
composition on dispersal success; furthermore, scale-dependent patterns in land cover and moisture gradients had a stronger
effect on longer- than shorter-ranging species types. Taken together, these simulations suggest that heuristic conservation
strategies could potentially be developed based on important but limited life history information. 相似文献
19.
Kimberley Adam Hooftman Danny Bullock James M. Honnay Olivier Krickl Patricia Lindgren Jessica Plue Jan Poschlod Peter Traveset Anna Cousins Sara A. O. 《Landscape Ecology》2021,36(1):265-280
Context
Functional connectivity is vital for plant species dispersal, but little is known about how habitat loss and the presence of green infrastructure interact to affect both functional and structural connectivity, and the impacts of each on species groups.
ObjectivesWe investigate how changes in the spatial configuration of species-rich grasslands and related green infrastructure such as road verges, hedgerows and forest borders in three European countries have influenced landscape connectivity, and the effects on grassland plant biodiversity.
MethodsWe mapped past and present land use for 36 landscapes in Belgium, Germany and Sweden, to estimate connectivity based on simple habitat spatial configuration (structural connectivity) and accounting for effective dispersal and establishment (functional connectivity) around focal grasslands. We used the resulting measures of landscape change to interpret patterns in plant communities.
ResultsIncreased presence of landscape connecting elements could not compensate for large scale losses of grassland area resulting in substantial declines in structural and functional connectivity. Generalist species were negatively affected by connectivity, and responded most strongly to structural connectivity, while functional connectivity determined the occurrence of grassland specialists in focal grasslands. Restored patches had more generalist species, and a lower density of grassland specialist species than ancient patches.
ConclusionsProtecting both species rich grasslands and dispersal pathways within landscapes is essential for maintaining grassland biodiversity. Our results show that increases in green infrastructure have not been sufficient to offset loss of semi-natural habitat, and that landscape links must be functionally effective in order to contribute to grassland diversity.
相似文献20.
Stephanie Kramer-Schadt Tobias S. Kaiser Karin Frank Thorsten Wiegand 《Landscape Ecology》2011,26(4):501-513
With habitat loss and fragmentation having become two of the major threats to the viability of species, the question of how
to manage landscapes for species conservation has attracted much attention. In this context, the planning of stepping stones
has been proposed to increase connectivity in fragmented landscapes. We present a simulation study with a neutral landscape
approach to assess the effects of stepping stones on colonization success. To that end, we used a spatially explicit, calibrated
population model of the European lynx (Lynx lynx) coupled with structured landscapes, in which we could control the landscape parameters of dispersal habitat coverage and
contagion, as well as the number and size of stepping stones available for breeding. In general, we found that colonization
success increased with increasing habitat coverage but decreased with increasing habitat contagion, while the introduction
of stepping stones had significant effects in critical situations. Especially at low to medium dispersal habitat coverage
and high disperser mortality, stepping stones had a positive effect on colonization success when they were large enough to
produce new dispersers, but negative effects when they were small and located in a way that dispersers would be distracted
from more suitable breeding habitat patches. The latter clearly constituted a shading effect and argues for a thorough consideration
of the trade-offs related to stepping stone size and location when implementing stepping stones as a conservation measure,
especially when the number of individuals of conservation concern is low. 相似文献