Populations In Fragmented Landscapes Research Articles

Spread of networked populations is determined by the interplay between dispersal behavior and habitat configuration

Predicting the spread of populations across fragmented habitats is vital if we are to manage their persistence in the long term. We applied network theory with a model and an experiment to show that spread rate is jointly defined by the configuration of habitat networks (i.e., the arrangement and length of connections between habitat fragments) and the movement behavior of individuals. We found that population spread rate in the model was well predicted by algebraic connectivity of the habitat network. A multigeneration experiment with the microarthropod Folsomia candida validated this model prediction. The realized habitat connectivity and spread rate were determined by the interaction between dispersal behavior and habitat configuration, such that the network configurations that facilitated the fastest spread changed depending on the shape of the species' dispersal kernel. Predicting the spread rate of populations in fragmented landscapes requires combining knowledge of species-specific dispersal kernels and the spatial configuration of habitat networks. This information can be used to design landscapes to manage the spread and persistence of species in fragmented habitats.

Myoglobin as a conservation‐relevant predictor of short‐distance flight capacity in Neotropical forest birds

AbstractSome forest‐dwelling tropical bird species are unable or unwilling to fly even a few hundred meters across habitat discontinuities, restricting connectivity of isolated populations in fragmented landscapes. Experimental evidence for flight limitation has reliably predicted occurrence across archipelagoes of habitat fragments varying in their distance from potential source populations. Mechanistic explanations for large differences in flight capacity of tropical birds, even over remarkably short distances, have not been tested. We evaluated myoglobin concentration in pectoralis muscles and hearts of eight Neotropical species for which experimental evidence revealing a wide range of flight abilities exists. We found a strong positive relationship between myoglobin concentration in the pectoralis muscles, but not hearts, and average overwater flight distance during dispersal‐challenge experiments. The approximately 2.5‐fold difference in pectoralis myoglobin concentration is directly associated with flight capacity and allows predictions of species or species groups most likely to be impeded by habitat discontinuities and therefore at conservation risk in fragmented landscapes.

Evaluating Release Strategy for Translocated Northern Bobwhites in Cross Timbers Ecoregion of Texas: A Pilot Study

Northern bobwhite (Colinus virginianus) population decline is largely driven by the loss, fragmentation, and degradation of grassland habitats. Translocation is used to reintroduce or augment populations in fragmented landscapes where natural dispersal is inhibited. Northern bobwhites have been successfully translocated in the southeastern portion of their range, but outcomes of translocations in western ranges have been mixed. Our objective was to conduct a pilot study to test the feasibility of translocating northern bobwhites to a restored, but isolated, habitat in the Cross Timbers ecoregion of Texas, USA and to evaluate the influence of release strategy for improving northern bobwhite site fidelity and survival post-release. The release property was restored through brush management, native species seeding, and proper grazing management. We trapped and translocated 84 northern bobwhites from source populations in the Rolling Plains and Edwards Plateau ecoregions during March 2015. Coveys were assigned to either delayed or immediate release treatment. We radio-collared all hens (n = 40; 11 adults; 29 juveniles) and evenly divided the sample between delayed and immediate releases. Delayed release coveys were held on the release site for 4 weeks in a Surrogator® (Wildlife Management Technologies, LLC). We trapped and radio-collared resident hens (n = 15) in March and monitored all hens through breeding season (March–August; 180 days). We implemented a 2-state (alive or dead) multistate model in Program MARK to analyze survival as a function of the release treatment, resident status, and age. We found no evidence that survival differed between translocated and resident hens (β = 0.48, standard error [SE] = 0.38), release treatments (β = 0.10, SE = 0.40), or age (β = -0.16, SE = 0.54). Daily survival for all hens was 0.99 (SE = 0.009) and breeding season survival was 0.19 (SE = 0.08). Four (20%) immediate, 2 (10%) delayed release, and 0 resident hens dispersed off-property. Translocated and resident hens survived at similar rates, indicating that translocation may be a feasible management strategy for augmenting a northern bobwhite population on restored habitats in the Cross Timbers ecoregion although overall survival was low. We did not find evidence that delayed release improved daily survival post-release, but our small sample size may have prevented us from detecting a difference. However, delayed release birds were effectively sheltered from predation during peak raptor migration. Additional research is needed to fully understand population dynamics and implications of release strategy for translocated northern bobwhite.

Modeling the persistence of plant populations in fragmented ecosystems

Ecosystem fragmentation is one of the main threats to species persistence via habitat reduction and isolation which often lead to species extinctions. A question that has long been of interest is the minimum habitat size that can sustain viable populations in fragmented landscape. Despite numerous empirical and theoretical efforts on this topic, most studies fail to address this central question, and our mechanistic understanding of and capacity to predict the effects and outcomes associated with fragmentation stressor is still illusive. We develop an ordinary differential equation (ODE) based framework that incorporates the effect of the patch area on the net population growth rate for a plant species in fragmented ecosystem via a general net growth function. We investigate the minimum patch area needed to sustain a given plant species. We use data from the Amazonian herb Heliconia acuminata to test our model. Furthermore, we compare the performance ODE model and a linear matrix model to predict the observed data. We provide a general formula for a threshold value for the fragment area, below which a plant population is not viable. For Heliconia acuminata, our ODE-based model predicts a value for the minimum fragment area of ≈0.7ha, which reflects the observed data and is smaller than the value obtained using the matrix projection model. Our findings suggest that the Heliconia’s mortality rate responds more negatively to fragmentation. Furthermore, we found that the ODE-based model can serve as an alternative to the linear demographic model.

A Multispecies Assessment to Identify the Functional Connectivity of Amphibians in a Human-Dominated Landscape

Preserving functional connectivity is a key goal of conservation management. However, the spatially confined conservation areas may not allow for dispersal and gene flow for the intended long-term persistence of populations in fragmented landscapes. We provide a regional multi-species assessment to quantify functional connectivity for five amphibian species in a human dominated landscape in the Swiss lowlands. A set of resistance maps were derived based on expert opinion and a sensitivity analysis was conducted to compare the effect of each resistance scenario on modelled connectivity. Deriving multi-species corridors is a robust way to identify movement hotspots that provide valuable baseline information to reinforce protective measures and green infrastructure.

Effects of grazing intensity, habitat area and connectivity on snail-shell nesting bees

The effects of habitat loss and fragmentation on wild bee populations are still not fully understood. Availability of resources, parasitism and habitat connectivity might influence population sizes of bees. Whereas floral resources for wild bees have been considered in research and conservation, nesting resources have been largely neglected as these are challenging to investigate. Snail shells are the exclusive nesting cavities for several Osmia species and provide a good - but so far unused - tool to study factors driving bee population dynamics. We investigated the effects of habitat area, connectivity and management of semi-natural grasslands on populations of snail-shell nesting bees. On 23 calcareous grasslands, we monitored snail shell colonization by providing empty snail shells as nesting resources, and recorded flower-visitor interactions.Five snail-shell nesting Osmia species were found on the grasslands, which made almost a quarter of recorded bee flower visits. Three species colonized the offered snail shells with high variation between study sites, Osmia species, and snail shell size. Habitat area had a positive effect on the population size of the habitat specialist Osmia aurulenta, whereas the more generalist species Osmia bicolor was positively influenced by habitat connectivity. Destruction rates of snail shells increased with sheep grazing intensity, leading to an estimated loss of more than a third of all bee nests. We conclude that large and connected habitats benefit bee populations in fragmented landscapes, while conservation management regimes should take into account potential negative effects of grazing on specific nesting resources of specialized bee species.

Recurrent seasonal occurrence of the Lineated Woodpecker (Dryocopus lineatus) in a riparian fragment of the Atlantic Forest, northeastern Brazil

Riparian forests play important roles as ecological corridors and refuge habitat for many bird populations in fragmented landscapes. This report describes the seasonal occurrence of the Lineated Woodpecker (Dryocopus lineatus) in a small riparian fragment of Atlantic Forest, northeastern Brazil. A female was recorded by its visual and acoustical signals from September to October 2014. Similar occurrences were observed in the same months over three consecutive years. Two major hypotheses regarding the woodpecker seasonal occurrence are discussed here: i) the use of the riparian fragment for breeding, evidenced by tree-cavity nests; and ii) fleeing of the bird from its natal habitat due to fire in adjacent sugarcane fields, which commonly are burned in these two months. Such recurrent events suggest that D. lineatus uses the riparian fragment as refuge habitat, highlighting the importance of these environments for bird populations that inhabit fragmented landscapes of the Brazilian Atlantic Forest.

Gene flow and effective population sizes of the butterfly Maculinea alcon in a highly fragmented, anthropogenic landscape

Understanding connectivity among populations in fragmented landscapes is of paramount importance in species conservation because it determines their long-term viability and helps to identify and prioritize populations to conserve. Rare and sedentary species are particularly vulnerable to habitat fragmentation as they occupy narrow niches or restricted habitat ranges. Here, we assess contemporary interpopulation connectedness of the threatened, myrmecophilous butterfly, Maculinea alcon, in a highly fragmented landscape. We inferred dispersal, effective population sizes, genetic diversity and structure based on 14 locations of M. alcon in Belgium and the Netherlands using data from 12 microsatellite loci. Despite the reported sedentary behaviour of M. alcon, we observed moderate levels of contemporary dispersal between patches, but only in landscapes where populations were located within a distance of 3km from neighbouring populations. Estimates of effective population sizes (Ne) were very low (ranging from 1.6 to 17.6) and bottleneck events occurred in most of the studied populations. We discuss the functional conservation units delineated based on a former mark-release-recapture study, and formulate appropriate conservation strategies to maintain viable (meta)populations in highly fragmented, anthropogenic landscapes.

An R package for simulating metapopulation dynamics and range expansion under environmental change

The metapopulation paradigm is central in ecology and conservation biology to understand the dynamics of spatially-structured populations in fragmented landscapes. Metapopulations are often studied using simulation modelling, and there is an increasing demand of user-friendly software tools to simulate metapopulation responses to environmental change. Here we describe the MetaLandSim R package, which integrates ideas from metapopulation and graph theories to simulate the dynamics of real and virtual metapopulations. The package offers tools to (i) estimate metapopulation parameters from empirical data, (ii) to predict variation in patch occupancy over time in static and dynamic landscapes, either real or virtual, and (iii) to quantify the patterns and speed of metapopulation expansion into empty landscapes. MetaLandSim thus provides detailed information on metapopulation processes, which can be easily combined with land use and climate change scenarios to predict metapopulation dynamics and range expansion for a variety of taxa and ecological systems.

Role of recreated habitats in butterfly conservation: a case study at Thenmala, Kerala, India

Focal species are valuable tools for evaluating management practices for biodiversity conservation. Butterfly gardening through the creation of appropriate habitats can be a primary conservation tool to increase species abundance and richness and gene flow among the populations in fragmented landscapes. In this context, the role of butterfly gardens in the conservation of butterfly populations and the seasonal population trends of swallowtail butterflies (family Papilionidae) sighted in the Butterfly Safari Park at Thenmala were studied. A total of 4760 sightings of 15 species of swallowtails belonging to five genera were recorded, of which six were endemic species, three species had protected status and two were rare species. It is worth noting that of the 19 species of the papilionids recorded in Kerala, as many as 15 species were recorded in Thenmala. Of the various species recorded, Troides minos, Pachliopta pandiyana, Pachliopta aristolochiae, Graphium agamemnon, Graphium sarpedon, Papilio polytes, Papilio clytia, Papilio demoleus and Papilio polymnestor comprised the resident populations, while species such as Atrophaneura hector, Papilio helenus, Papilio dravidarum, Papilio paris, Papilio liomedon and Graphium nomius were found only during certain seasons. The overall butterfly abundance was high from August to November. The butterfly populations exhibited a gradual decline in numbers from December onwards with the onset of dry seasons. The abundance of butterfly populations was low during March–April. The abundance of T. minos, P. pandiyana, P. polymnestor, P. paris, P. dravidarum, P. helenus, P. polytes and P. liomedon showed a significant negative correlation with monthly average temperature and a significant positive correlation with humidity.

Demographic parameters of sexes in an elusive insect: implications for monitoring methods

AbstractEstimating demographic parameters in rare species is challenging because of the low number of individuals and their cryptic behaviour. One way to address this challenge is to gather data from several regions or years through mark‐release‐recapture (MRR) and radio‐tracking monitoring. However, the comparison of demographic estimates obtained using these methods has rarely been investigated. Using 5 years of intensive MRR and radio‐tracking surveys of an elusive and endangered saproxylic insect, the hermit beetle (Osmoderma eremita), in two regions of France, we aimed to estimate population size at the adult stage for each sex separately and to assess differences in demographic parameter estimates between survey methods. We found that males were approximately three times more likely to be recaptured than females. Taking this into account, we determined that the sex ratio was male‐biased in almost all populations, except in Malus trees, where it was female‐biased. Temporal fluctuations of sex ratios were also detected in one region. The radio‐tracking transmitter (450 mg) allowed only the largest individuals (>2 g) to be targeted. However, we found that, among non‐equipped individuals, the larger males survived better than the smaller males. We also confirmed that transmitter‐equipped individuals survived approximately 25 % better than non‐equipped individuals. Extrapolating the estimates from radio‐tracking surveys to the population scale may result in overly optimistic population projections. Our results revealed large temporal and spatial variations in population size and sex ratios. This knowledge is crucial for predicting the persistence of small populations in fragmented landscapes. This study also questioned the representativeness of radio‐tracking surveys for insect species in estimating demographic parameters at the population scale.

Assessing habitat connectivity for ground-dwelling animals in an urban environment.

To ensure viable species populations in fragmented landscapes, individuals must be able to move between suitable habitat patches. Despite the increased interest in biodiversity assessment in urban environments, the ecological relevance of habitat connectivity in highly fragmented landscapes remains largely unknown. The first step to understanding the role of habitat connectivity in urban ecology is the challenging task of assessing connectivity in the complex patchwork of contrasting habitats that is found in cities. We developed a data-based framework, minimizing the use of subjective assumptions, to assess habitat connectivity that consists of the following sequential steps: (1) identification of habitat preference based on empirical habitat-use data; (2) derivation of habitat resistance surfaces evaluating various transformation functions; (3) modeling of different connectivity maps with electrical circuit theory (Circuitscape), a method considering all possible pathways across the landscape simultaneously; and (4) identification of the best connectivity map with information-theoretic model selection. We applied this analytical framework to assess habitat connectivity for the European hedgehog Erinaceus europaeus, a model species for ground-dwelling animals, in the city of Zurich, Switzerland, using GPS track points from 40 individuals. The best model revealed spatially explicit connectivity “pinch points,” as well as multiple habitat connections. Cross-validation indicated the general validity of the selected connectivity model. The results show that both habitat connectivity and habitat quality affect the movement of urban hedgehogs (relative importance of the two variables was 19.2% and 80.8%, respectively), and are thus both relevant for predicting urban animal movements. Our study demonstrates that even in the complex habitat patchwork of cities, habitat connectivity plays a major role for ground-dwelling animal movement. Data-based habitat connectivity maps can thus serve as an important tool for city planners to identify habitat corridors and plan appropriate management and conservation measures for urban animals. The analytical framework we describe to model such connectivity maps is generally applicable to different types of habitat-use data and can be adapted to the movement scale of the focal species. It also allows evaluation of the impact of future landscape changes or management scenarios on habitat connectivity in urban landscapes.

The jaguar's patches: Viability of jaguar populations in fragmented landscapes

Habitat loss and fragmentation have serious consequences for long-term population persistence, thus we investigated the effects of these processes on jaguars (Panthera onca) across the species’ distribution range. We employed theoretical simulations of population dynamics, making use of real and hypothetical landscapes to understand how landscape patterning affects the long-term persistence of species, and investigated the isolated and synergistic effects of habitat loss and fragmentation. Jaguar persistence probability was related both to the amount and pattern of landscape subdivision, but with a strong tolerance for habitat loss because the amount of habitat could be between 230 and 5841km2. In contrast, the persistence probability of smaller jaguar populations decreased dramatically in fragmented landscapes, indicating that fragmentation is a greater threat to jaguar long-term viability than habitat loss. Only two of the 28 populations included in our study were deemed viable in the long-term. Given the increase in habitat fragmentation and the current threat status of the jaguar, we discuss the best strategies for their conservation.

Is the matrix important to butterflies in fragmented landscapes?

The quality and extent of the ‘matrix’ in terrestrial fragmented landscapes may influence the persistence and behaviour of patch-associated fauna. Butterflies are a popular target group for fragmentation studies and represent an ideal assemblage to explore the impact and role of the matrix in patchy landscapes. To date, there has been no attempt to synthesise available research and assess the extent to which the matrix is included in studies of fragmented butterfly populations. Addressing this issue is important for improved understanding of habitat use in fragmented landscapes, and for the successful management and conservation of butterfly biodiversity. Our systematic review of 100 empirical research papers spans 50 years, and identifies how (and indeed if) the matrix is recognised in studies of butterfly populations in fragmented landscapes. We found that it was significantly more likely for studies not to include the matrix in their experimental design. This is of particular concern given 60 % of papers that excluded the matrix in their research did so in systems where the matrix was expected to contain resources of value for patch-associated species (as it was either a heterogeneous landscape or had similar structure to patches). Of the papers that did consider the matrix, 80 % (n = 24) reported a negative effect of the matrix on butterfly species and/or communities. Matrix effects may influence the survival and persistence of faunal groups in a world increasingly dominated by fragmented habitats. Our review suggests that future research should clearly define the matrix, and incorporate it in appropriate experimental designs.

Impact of Phytophthora-dieback on birds in Banksia woodlands in south west Western Australia

Invasive plant pathogens have impacted forest and woodland systems globally and can negatively impact biodiversity. The soil-borne plant pathogen Phytophthora cinnamomi is listed as one of the world’s worst invasive species and alters plant community composition and habitat structure. Few studies have examined how these Phytophthora-induced habitat changes affect faunal communities. We examined bird communities in Banksia woodland with, and without, Phytophthora dieback in a biodiversity hotspot, southwestern Australia. Seven sites along dieback fronts, with paired 1-ha plots in diseased and healthy vegetation, were surveyed monthly for birds over seven months. Vegetation assessments showed that diseased sites had reduced plant species richness, litter, shrub, tree and canopy cover, high bare ground and significantly lower flowering scores, than healthy sites. Bird community composition differed significantly between diseased and healthy sites, although total bird abundance, total species richness and foraging guilds, did not. Average species richness of birds per survey and the abundance of brown honeyeaters, western spinebills and silvereyes was lower in diseased than healthy sites. The tawny-crowned honeyeater had higher abundances in diseased sites. Similarity matrices of habitat structure, flowering scores and bird assemblages were congruent, indicating that habitat structural differences were influencing bird community composition. Our results suggest that this pathogen is potentially a serious threat to avian biodiversity and especially for nectarivores, and populations in fragmented landscapes. Since elimination of the pathogen is not currently possible, management should focus on methods of preventing its spread until techniques to eliminate the pathogen are developed.

Spreading speeds for stage structured plant populations in fragmented landscapes

Landscape fragmentation has huge ecological and economic implications and affects the spatial dynamics of many plant species. Determining the speed of population spread in fragmented/heterogeneous landscapes is therefore of utmost importance to ecologists. Stage-structured integrodifference equations (IDEs) are deterministic models which accurately reflect the life cycles and dispersal patterns for numerous species. Existing approximations to wave-speeds consider only particular kernels, or landscapes in which the scale of variation is much smaller than the dispersal scale. We propose an analytical approximation to the wave-speeds of IDE solutions with periodic landscapes of alternating good and bad patches, where the dispersal scale is greater than the extent of each good patch and where the ratio of the demographic rates in the good and bad patches is given by a small parameter, denoted as ε. We formulate this approximation for the Gaussian and Laplace dispersal kernels and for stage structured and non-stage structured populations, and compare the results against numerical simulations. We find that the approximation is accurate for the landscapes considered, and that the type of dispersal kernel affects the relationship between landscape structure, as classified by landscape period and good patch size, and the spreading speed. This indicates that accurately fitting a kernel to data is important in determining the relationship between landscape structure and spreading speed.

Unpaved road verges as hotspots of fleshy-fruited shrub recruitment and establishment

Hypothetical low-quality habitats can hold an overlooked conservation value. Some frugivorous mammals such as the red fox (Vulpes vulpes) and the European rabbit (Oryctolagus cuniculus) disperse many viable seeds of fleshy-fruited shrubs along the verges of soft linear developments (SLD), such as trails and firebreaks. However, seed arrival does not guarantee plant recruitment, since several post-dispersal processes can alter seed rain. To examine whether SLD verges assist shrub recruitment and establishment, we compared the density and the structure of a community of Mediterranean shrubs between SLD verges and the adjacent scrubland.Both seedlings and adult fleshy-fruited shrubs dispersed by foxes and rabbits reached higher densities along SLD verges than in the scrubland, suggesting SLD verges can be suitable habitats for shrub recruitment and establishment. Bird-dispersed shrubs showed a similar pattern, whereas shrubs dispersed by ungulates and badgers (Meles meles) as well as rockroses (Cistaceae) showed similar densities in both habitats. Shrub species composition and diversity were similar between habitats.Due to a marked differential seed arrival, SLD verges housed higher densities of fleshy-fruited shrubs than the adjacent scrubland. Established shrubs may attract seed-dispersing wildlife, and create proper environments for plant recruitment, generating a reforestation feedback. Incipient shrub populations along roadsides may act as stepping stones with potential to connect isolated populations in fragmented landscapes, where SLD are pervasive. We recommend careful management of frugivore populations and SLD verges in order to favor the diversity and the structural complexity of native vegetation while preventing the spread of invasive species.

The relative impact of forest patch and landscape attributes on black howler monkey populations in the fragmented Lacandona rainforest, Mexico

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.

Mice on the move: Wheat rows as a means to increase permeability in agricultural landscapes

A crucial factor in determining the persistence of animal populations in fragmented landscapes is the individual’s ability to move through a hostile man-made environment (the agricultural matrix). Previous studies suggested appropriate orientation of manioc plantation rows as a possible means to facilitate animal movements and to increase landscape functional connectivity.The goal of our work was to broaden our understanding of plantation rows as a means to increase permeability in cereal-crop-dominated landscapes. In particular, we focused on (a) analyzing animals’ ability to localize and move towards habitat fragments in different matrix types (i.e. their perceptual ranges) and (b) testing whether the orientation of wheat rows acted as dispersal route during three stages of the wheat plant maturation.We carried out release experiments in an agricultural landscape of central Italy on three species of rodents: two forest specialists (Apodemus flavicollis and Myodes glareolus) and a habitat generalist (Apodemus sylvaticus). We released individuals in three matrix types (a bare field, a grass field and a wheat field at three maturation stages) and followed their movements. We found that (a) perceptual ranges were species- and matrix-specific, (b) individuals followed plantation rows when moving through the matrix at any stage of wheat growth, including recently planted wheat, (c) in the grass field individuals did not follow any preferential direction. These results provide strong empirical evidence that wheat plantation rows should be planted orientated between habitat patches and should be considered as a complementary conservation strategy to increase connectivity in agricultural landscapes.

The genetic structure of populations of Metrioptera bicolor in a spatially structured landscape: effects of dispersal barriers and geographic distance

The stability and long-term survival of animal populations in fragmented landscapes largely depends on the colonisation of habitat patches and the exchange of individuals between patches. The degree of inter-patch dispersal, in turn, depends on the dispersal abilities of species and the landscape structure (i.e. the nature of the landscape matrix and habitat distribution). Here, we investigated the genetic structure of populations of Metrioptera bicolor, a wing-dimorphic bush cricket, in a spatially structured landscape with patches of suitable habitat distributed within a diverse matrix of different habitat types. Using six microsatellite markers, we assessed the effects of geographic distance and different matrix types on the extent of genetic differentiation among 24 sampling sites. We found that forest and a river running through the study area both impede inter-patch dispersal. The presence of these two matrix types was positively correlated with the extent of genetic differentiation between sites. In addition, we found a significant positive correlation between pairwise genetic and geographic distances for a subsample of sites which were separated only by arable land or settlements. For the complete data set, this correlation could not be found. This is most probably because the adverse effect of forest and river on gene flow dominates the effect of geographic distance in our limited set of patches. Our analyses clearly emphasize the differential resistance of different habitat types on dispersal and the importance of a more detailed view on matrix “quality” in metapopulation studies.