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1.
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
2.
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
3.
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
4.
Effects of patch attributes, barriers, and distance between patches on the distribution of a rock-dwelling rodent (Lagidium viscacia) 总被引:1,自引:0,他引:1
We tested whether size of habitat patches and distance between patches are sufficient to predict the distribution of the mountain
vizcacha Lagidium viscacia a large, rock-dwelling rodent of the Patagonian steppe Argentina, or whether information on other patch and landscape characteristics
also is required. A logistic regression model including the distance between rock crevices and depth of crevices, distance
between a patch and the nearest occupied patch, and whether or not there was a river separating it from the nearest occupied
patch was a better predictor of patch occupancy by mountain vizcachas than was a model based only on patch size and distance
between patches. Our results indicate that a simple metapopulation analysis based on size of habitat patches and distance
between patches may not provide an accurate representation of regional population dynamics if patches vary in habitat quality
independently of patch size and features in the matrix alter connectivity.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
5.
A comparison of metrics predicting landscape connectivity for a highly interactive species along an urban gradient in Colorado, USA 总被引:1,自引:1,他引:0
Many organisms persist in fragmented habitat where movement between patches is essential for long-term demographic and genetic
stability. In the absence of direct observation of movement, connectivity or isolation metrics are useful to characterize
potential patch-level connectivity. However, multiple metrics exist at varying levels of complexity, and empirical data on
species distribution are rarely used to compare performance of metrics. We compared 12 connectivity metrics of varying degrees
of complexity to determine which metric best predicts the distribution of prairie dog colonies along an urban gradient of
385 isolated habitat patches in Denver, Colorado, USA. We found that a modified version of the incidence function model including
area-weighting of patches and a cost-weighted distance surface best predicted occupancy, where we assumed roads were fairly
impermeable to movement, and low-lying drainages provided dispersal corridors. We also found this result to be robust to a
range of cost weight parameters. Our results suggest that metrics should incorporate both patch area and the composition of
the surrounding matrix. These results provide guidance for improved landscape habitat modeling in fragmented landscapes and
can help identify target habitat for conservation and management of prairie dogs in urban systems. 相似文献
6.
The distribution of the northern brown bandicoot (Isoodon macrourus), a medium-sized ground-dwelling marsupial, was examined in habitat fragments within the urban landscape of the city of Brisbane,
Australia. From surveys conducted in 68 fragments, bandicoots were found to be present in 33 (49%) despite widespread habitat
loss and fragmentation. Logistic regression analysis revealed that of 13 measured independent variables, functional connectivity
was the only factor that significantly predicted the presence of bandicoots within fragments, with connectivity positively
correlated with the likelihood of occupation. Functional connectivity was equated to the likelihood of bandicoot immigration
into the focal fragment from the nearest occupied fragment, based on the estimated resistance to movement offered by the intervening
matrix. Within Brisbane, riparian habitat fragments typically have a relatively high level of functional connectivity, as
thin strips of vegetation fringing waterways serve as corridors between larger riparian areas and facilitate the movement
of bandicoots between patches. Analyses based on the Akaike Information Criterion revealed that the optimal model based on
landscape context variables was convincingly better supported by the data than the optimal model produced from fragment characteristics.
However, it is important to examine both internal attributes of habitat fragments and external features of the surrounding
landscape when modelling the distribution of ground-dwelling fauna in urban environments, or other landscapes with a highly
variable matrix. As urban centres throughout the world expand, it is crucial that the ecology of local wildlife be considered
to ensure functional connection is maintained between habitat patches, especially for the conservation of species that are
highly susceptible to fragmentation. 相似文献
7.
Modeling patch occupancy: Relative performance of ecologically scaled landscape indices 总被引:1,自引:1,他引:0
In fragmented landscapes, the likelihood that a species occupies a particular habitat patch is thought to be a function of
both patch area and patch isolation. Ecologically scaled landscape indices (ESLIs) combine a species’ ecological profile,
i.e., area requirements and dispersal ability, with indices of patch area and connectivity. Since their introduction, ESLIs
for area have been modified to incorporate patch quality. ESLIs for connectivity have been modified to incorporate niche breadth,
which may influence a species’ ease in crossing the non-habitat matrix between patches. We evaluated the ability of 4 ESLIs,
the original and modified indices of area and connectivity, to explain patterns in patch occupancy of 5 forest rodents. Occupancy
of eastern gray squirrels (Sciurus carolinensis), North American red squirrels (Tamiasciurus hudsconicus), fox squirrels (Sciurus niger), white-footed mice (Peromyscus leucopus), and eastern chipmunks (Tamias striatus) was modeled at 471 sites in 35 landscapes sampled from the upper Wabash River basin in Indiana. Models containing ESLIs
received support for gray squirrels, red squirrels, and chipmunks. Modified ESLIs were important in models for red squirrels.
However, none of the models demonstrated high predictive ability. Incorporating habitat quality and using surrogate measures
of dispersal can have important effects on model results. Additionally, different responses of species to area, isolation,
and habitat quality suggest that generalizing patterns of metapopulation dynamics was not justified, even across closely related
species. 相似文献
8.
Acknowledgment that the matrix matters in conserving wildlife in human-modified landscapes is increasing. However, the complex
interactions of habitat loss, habitat fragmentation, habitat condition and land use have confounded attempts to disentangle
the relative importance of properties of the landscape mosaic, including the matrix. To this end, we controlled for the amount
of remnant forest habitat and the level of fragmentation to examine mammal species richness in human-modified landscapes of
varying levels of matrix development intensity and patch attributes. We postulated seven alternative models of various patch
habitat, landscape and matrix influences on mammal species richness and then tested these models using generalized linear
mixed-effects models within an information theoretic framework. Matrix attributes were the most important determinants of
terrestrial mammal species richness; matrix development intensity had a strong negative effect and vegetation structural complexity
of the matrix had a strong positive effect. Distance to the nearest remnant forest habitat was relatively unimportant. Matrix
habitat attributes are potentially a more important indicator of isolation of remnant forest patches than measures of distance
to the nearest patch. We conclude that a structurally complex matrix within a human-modified landscape can provide supplementary
habitat resources and increase the probability of movement across the landscape, thereby increasing mammal species richness
in modified landscapes. 相似文献
9.
Comparing the landscape level perceptual abilities of forest sciurids in fragmented agricultural landscapes* 总被引:8,自引:2,他引:6
Perceptual range is the maximum distance from which an animal can perceive the presence of remote landscape elements such as patches of habitat. Such perceptual abilities are of interest because they influence the probability that an animal will successfully disperse to a new patch in a landscape. Furthermore, understanding how perceptual range differs between species may help to explain differential species sensitivity to patch isolation. The objective of this research was to assess the perceptual range of eastern chipmunks (Tamias striatus), gray squirrels (Sciurus carolinensis), and fox squirrels (Sciurus niger) in fragmented agricultural landscapes. Animals were captured in remote woodlots and translocated to unfamiliar agricultural fields. There they were released at different distances from a woodlot and their movements towards or away from the woodlot were used to assess their ability to perceive forested habitat. Observed perceptual ranges of approximately 120 m for chipmunks, 300 m for gray squirrels, and 400 m for fox squirrels, suggest that differences in landscape-level perceptual abilities may influence the occurrence of these species in isolated habitat patches. 相似文献
10.
Víctor Arroyo-Rodríguez Iraida M. González-Perez Adriana Garmendia Mireia Solà Alejandro Estrada 《Landscape Ecology》2013,28(9):1717-1727
Land-use change is forcing many animal populations to inhabit forest patches in which different processes can threaten their survival. Some threatening processes are mainly related to forest patch characteristics, but others depend principally on the landscape spatial context. Thus, the impact of both patch and landscape spatial attributes needs to be assessed to have a better understanding of the habitat spatial attributes that constraint the maintenance of populations in fragmented landscapes. Here, we evaluated the relative effect of three patch-scale (i.e., patch size, shape, and isolation) and five landscape-scale metrics (i.e., forest cover, fragmentation, edge density, mean inter-patch isolation distance, and matrix permeability) on population composition and structure of black howler monkeys (Alouatta pigra) in the Lacandona rainforest, Mexico. We measured the landscape-scale metrics at two spatial scales: within 100 and 500 ha landscapes. Our findings revealed that howler monkeys were more strongly affected by local-scale metrics. Smaller and more isolated forest patches showed a lower number of individuals but at higher densities. Population density also tended to be positively associated to matrices with higher proportion of secondary forests and arboreal crops (i.e. with greater permeability), most probably because these matrices can offer supplementary foods. The immature-to-female ratio also increased with matrix permeability, shape complexity, and edge density; habitat characteristics that can increase landscape connectivity and sources availability. The prevention of habitat loss and isolation, and the increment of matrix permeability are therefore needed for the conservation of this endangered Neotropical mammal. 相似文献
11.
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
12.
Since the fragmentation of natural habitats is one of the most serious problems for many endangered species, it is highly interesting to study the properties of fragmented landscapes. As a basic property, landscape connectivity and its effects on various ecological processes are frequently in focus. First, we discuss the relevance of some graph properties in quantifying connectivity. Then, we propose a method how to quantify the relative importance of habitat patches and corridors in maintaining landscape connectivity. Our combined index explicitly considers pure topological properties and topographical measures, like the quality of both patches (local population size) and corridors (permeability). Finally, for illustration, we analyze the landscape graph of the endangered, brachypterous bush-cricket Pholidoptera transsylvanica. The landscape contains 11 patches and 13 corridors and is situated on the Aggtelek Karst, NE-Hungary. We characterize the importance of each node and link of the graph by local and global network indices. We show how different measures of connectivity may suggest different conservation preferences. We conclude, accordingly to our present index, by identifying one specific habitat patch and one specific corridor being in the most critical positions in maintaining connectivity.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
13.
Tick density and population dynamics are important factors in the ecological processes involved in pathogen circulation in
a habitat. These characteristics of tick populations are closely linked to habitat suitability, which reflects the limiting
ecological factors and landscape features affecting tick populations; however, little work has been done on the regional assessment
of habitat suitability. In this study, a regional model for the distribution and abundance of the tick Ixodes ricinus in central Spain is developed. An occurrence and an abundance model were constructed; climate and vegetation variables were
found to be the main predictors of both occurrence and density in a relatively homogeneous matrix of habitat patches, whereas
topographical variables were found to have small contributions and were therefore discarded. The residuals of the abundance
model showed good correlation with the isolation of each patch. The predictive power of the abundance model was greatly enhanced
by inclusion of the traversability (a measure of the permeability of each patch to the propagules of the metapopulation) and
recruitment (an index of the relative importance of each patch to the traffic through the entire habitat network). The removal
from the landscape of the patches whose recruitment values were in the top 10% has a critical effect on tick density, an effect
not observed when patches are removed at random. These results indicate that permanent tick populations can be sustained only
in landscapes containing a minimum network of viable sites. Graph theory and measurements of patch isolation should prove
to be important elements in the forecasting of tick abundance and the management of the features underlying the landscape
ecology of tick populations and pathogen circulation in the field. 相似文献
14.
Maintaining connectivity among local populations in a fragmented landscape is crucial for the survival of many species. For
isolated habitat patches, stochastic fluctuations and reduced gene flow can lead to high risk of extinction. The connectivity
of the landscape is especially crucial for the carabid species living in the fragmented forests of the Bereg plain (NE Hungary
and W Ukraine) because a highway will be constructed through the plain. Our purpose is to (1) evaluate the impacts of three
possible highway tracks, (2) suggest a solution that is realistic with less impact on connectivity than other plans and (3)
discuss how to decrease the disadvantageous effects of each track. Our results, based on a network analysis of landscape graph
of patches and ecological corridors, indicate that the intended highway could have deleterious consequences on forest-living
carabids. Relatively simple actions, like the establishment of stepping stones, could compensate for the loss of habitat connectivity
and promote the survival of carabids, or minor modifications in one possible track could diminish its adverse effects. While
many other studies would be needed for a comprehensive assessment of the biotic impact of the highway, we provide an example
on the usefulness of network analysis for land use management.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
15.
In fragmented landscapes, plant species persistence depends on functional connectivity in terms of pollen flow to maintain
genetic diversity within populations, and seed dispersal to re-colonize habitat patches following local extinction. Connectivity
in plants is commonly modeled as a function of the physical distance between patches, without testing alternative dispersal
vectors. In addition, pre- and post-dispersal processes such as seed production and establishment are likely to affect patch
colonization rates. Here, we test alternative models of potential functional connectivity with different assumptions on source
patch effects (patch area and species occupancy) and dispersal (relating to distance among patches, matrix composition, and
sheep grazing routes) against empirical patch colonization rates at the community level (actual functional connectivity),
accounting for post-dispersal effects in terms of structural elements providing regeneration niches for establishment. Our
analyses are based on two surveys in 1989 and in 2009 of 48 habitat specialist plants in 62 previously abandoned calcareous
grassland patches in the Southern Franconian Alb in Bavaria, Germany. The best connectivity model S
i
, as identified by multi-model inference, combined distance along sheep grazing routes including consistently and intermittently
grazed patches with mean species occupancy in 1989 as a proxy for pre-dispersal effects. Community-level patch colonization
rates depended to equal degrees on connectivity and post-dispersal process. Our study highlights that actual functional connectivity
of calcareous grassland communities cannot be approximated by structural connectivity based on physical distance alone, and
modeling of functional connectivity needs to consider pre- and post-dispersal processes. 相似文献
16.
Effects of different matrix representations and connectivity measures on habitat network assessments
Assessing landscape connectivity is important to understand the ecology of landscapes and to evaluate alternative conservation strategies. The question is though, how to quantify connectivity appropriately, especially when the information available about the suitability of the matrix surrounding habitat is limited. Our goal here was to investigate the effects of matrix representation on assessments of the connectivity among habitat patches and of the relative importance of individual patches for the connectivity within a habitat network. We evaluated a set of 50 × 50 km2 test areas in the Carpathian Mountains and considered three different matrix representations (binary, categorical and continuous) using two types of connections among habitat patches (shortest lines and least-cost paths). We compared connections, and the importance of patches, based on (1) isolation, (2) incidence-functional, and (3) graph measures. Our results showed that matrix representation can greatly affect assessments of connections (i.e., connection length, effective distance, and spatial location), but not patch prioritization. Although patch importance was not much affected by matrix representation, it was influenced by the connectivity measure and its parameterization. We found the biggest differences in the case of the integral index of connectivity and equally weighted patches, but no consistent pattern in response to changing dispersal distance. Connectivity assessments in more fragmented landscapes were more sensitive to the selection of matrix representation. Although we recommend using continuous matrix representation whenever possible, our results indicated that simpler matrix representations can be also used as a proxy to delineate those patches that are important for overall connectivity, but not to identify connections among habitat patches. 相似文献
17.
Yu-Huang Wang Kuoh-Cheng Yang Cara Lin Bridgman Liang-Kong Lin 《Landscape Ecology》2008,23(8):989-1000
Landscape connectivity is important in designing corridor and reserve networks. Combining genetic distances among individuals
with least-cost path (LCP) modelling helps to correlate indirect measures of gene flow with landscape connectivity. Applicability
of LCP modelling, however, is reduced if knowledge on dispersal pathways or routes is lacking. Therefore, we integrated habitat
suitability modelling into LCP analysis to avoid the subjectivity common in LCP analyses lacking knowledge on dispersal pathways
or routes. We used presence-only data and ecological niche factor analysis to model habitat suitability for the spiny rat,
Niviventer coninga, in a fragmented landscape of western Taiwan. We adapted the resultant habitat suitability map for incorporation into LCP
analyses. Slightly increased Mantel correlations indicated that a class-weighted suitability map better explained genetic
distances among individuals than did geographical distances. The integration of habitat suitability modelling into LCP analysis
can thus generate information on distribution of suitable habitats, on potential routes of dispersal, for placement of corridors,
and evaluate landscape connectivity.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
18.
The landscape matrix modifies the effect of habitat fragmentation in grassland butterflies 总被引:1,自引:0,他引:1
Erik ?ckinger Karl-Olof Bergman Markus Franzén Tomá? Kadlec Jochen Krauss Mikko Kuussaari Juha P?yry Henrik G. Smith Ingolf Steffan-Dewenter Riccardo Bommarco 《Landscape Ecology》2012,27(1):121-131
The landscape matrix is suggested to influence the effect of habitat fragmentation on species richness, but the generality
of this prediction has not been tested. Here, we used data from 10 independent studies on butterfly species richness, where
the matrix surrounding grassland patches was dominated by either forest or arable land to test if matrix land use influenced
the response of species richness to patch area and connectivity. To account for the possibility that some of the observed
species use the matrix as their main or complementary habitat, we analysed the effects on total species richness and on the
richness of grassland specialist and non-specialist (generalists and specialists on other habitat types) butterflies separately.
Specialists and non-specialists were defined separately for each dataset. Total species richness and the richness of grassland
specialist butterflies were positively related to patch area and forest cover in the matrix, and negatively to patch isolation.
The strength of the species-area relationship was modified by matrix land use and had a slope that decreased with increasing
forest cover in the matrix. Potential mechanisms for the weaker effect of grassland fragmentation in forest-dominated landscapes
are (1) that the forest matrix is more heterogeneous and contains more resources, (2) that small grassland patches in a matrix
dominated by arable land suffer more from negative edge effects or (3) that the arable matrix constitutes a stronger barrier
to dispersal between populations. Regardless of the mechanisms, our results show that there are general effects of matrix
land use across landscapes and regions, and that landscape management that increases matrix quality can be a complement to
habitat restoration and re-creation in fragmented landscapes. 相似文献
19.
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
20.
Loss of connectivity is one of the main causes of decreases in habitat availability and, thus, in species abundance and occurrence
in fragmented landscapes. It is therefore important to measure habitat connectivity for conservation purposes, but there are
several difficulties in quantifying connectivity, including the need for species movement behavioral data and the existence
of few consistent indices to describe such data. In the present study, we used a graph theoretical framework to measure habitat
availability, and we evaluate whether this variable is adequate to explain the occurrence pattern of an Atlantic rainforest
bird (Pyriglena leucoptera, Thamnophilidae). The playback technique was used to parameterize the connectivity component of habitat availability indices
and to determine the presence or absence of the study species in forest patches. Patch- and landscape-level habitat availability
indices were considered as explanatory variables. Two of these were landscape-level indices, which varied in terms of how
inter-patch connections are defined, using either a binary or probabilistic approach. This study produced four striking results.
First, even short open gaps may disrupt habitat continuity for P. leucoptera. Second, the occurrence of P. leucoptera was positively affected by habitat availability. Third, proper measures of this explanatory variable should account for the
landscape context around the focal patch, emphasizing the importance of habitat connectivity. Finally, habitat availability
indices should consider probabilistic and not binary inter-patch connections when intending to explain the occurrence of bird
species in fragmented landscapes. We discuss some conservation implications of our results, stressing the advantages of an
ecologically scaled graph theoretical framework. 相似文献