Influence Of Landscape Features Research Articles

Sex and landscape influence spatial genetic variation in a large fossorial mammal, the Bare-nosed Wombat (Vombatus ursinus).

Dispersal is an important process that is widely studied across species, and it can be influenced by intrinsic and extrinsic factors. Intrinsic factors commonly assessed include the sex and age of individuals, while landscape features are frequently-tested extrinsic factors. Here, we investigated the effects of both sex and landscape composition and configuration on genetic distances among bare-nosed wombats (Vombatus ursinus)-one of the largest fossorial mammals in the world and subject to habitat fragmentation, threats from disease, and human persecution including culling as an agricultural pest. We analyzed a data set comprising 74 Tasmanian individuals (30 males and 44 females), genotyped for 9,064 single-nucleotide polymorphisms. We tested for sex-biased dispersal and the influence of landscape features on genetic distances including land use, water, vegetation, elevation, and topographic ruggedness. We detected significant female-biased dispersal, which may be related to females donating burrows to their offspring due to the energetic cost of excavation, given their large body sizes. Land use, waterbodies, and elevation appeared to be significant landscape predictors of genetic distance. Land use potentially reflects land clearing and persecution over the last 200 years. If our findings based on a limited sample size are valid, retention and restoration of nonanthropogenic landscapes in which wombats can move and burrow may be important for gene flow and maintenance of genetic diversity.

The influence of landscape features on the population connectivity and genetic structure of the Edible Dormouse Glis glis in Poland

Abstract In this study, we analyze and compare the genetic structure of edible dormice representing five populations, inhabiting forest complexes in southwestern Poland that differ in their degree of fragmentation and isolation. Total genomic DNA was isolated from hairs with bulbs of 145 individuals captured between 2018 and 2020. All dormice sampled were genotyped at 14 microsatellite loci. Population genetic analyses showed that genetic variability in the studied dormice, assessed based on observed and expected heterozygosity as well as allelic richness, was on average very low (0.39, 0.43, and 2.83, respectively). In the populations studied, genetic structure was detected indicating two or five distinct genetic clusters, the existence of which can be attributed to either historical factors or modern human activity. Genetic differentiation between dormice living in the studied localities, determined by FST, ranged from 0.07 to 0.40 (all FST coefficients were significant at P < 0.05). A significant positive correlation was detected between genetic differentiation and geographic distance (r = 0.645, P < 0.017), indicating that genetic differentiation increases with distance, but no correlation between genetic differentiation and habitat barriers (r = 0.359, P < 0.132). The results of this research are compared to those of other European populations of edible dormice, and implications for the future of this endangered species are discussed.

Landscape characteristics influence regional dispersal in a high-elevation specialist migratory bird, the water pipit Anthus spinoletta.

Species living in high mountain areas are currently threatened by climate change and human land use changes. High-elevation birds frequently inhabit island-like suitable patches around mountain peaks, and in such conditions the capability to exchange individuals among patches is crucial to maintain gene flow. However, we lack information regarding the dispersal ability of most of these species and the possible influence of landscape features on dispersal. In this study, we used population genomics and landscape resistance modelling to investigate dispersal in a high-elevation specialist migratory bird, the water pipit Anthus spinoletta. We aimed to assess the levels of gene flow in this species within a wide area of the European Alps, and to assess the effects of environmental characteristics on gene flow, by testing the isolation by distance (IBD) hypothesis against the isolation by resistance (IBR) hypothesis. We found clear support for IBR, indicating that water pipits preferentially disperse across suitable breeding habitat (i.e., high-elevation grassland). IBR was stronger in the part of the study area with less extended suitable habitat. Landscape resistance was slightly better described by habitat suitability models than landscape connectivity models. Despite the observed IBR, gene flow within the study area was high, probably also because of the still wide and relatively continuous breeding range. The forecasted reduction of range of this species may lead to stronger effects of IBR on gene flow. Other high-elevation specialist birds may show similar IBR patterns, but with possibly stronger effects on gene flow because of their more reduced and patchy habitats.

Changes in the Content of Mobile Forms of Nitrogen in Gray Forest Soils of Opole under the Influence of Landscape Features

In a long-term stationary experiment on gray forest soils of the Vladimir Opole, the influence of agricultural technologies of cultivation of field crops on the content of mobile forms of nitrogen, their relationship with chemical and physico-chemical properties of the soil, levels of intensification have been studied. After a longterm application of agricultural technologies with an increase in the level of fertilizer application, an increase in nitrate nitrogen reserves, the degree of transition of ammonium nitrogen of the soil to the liquid phase from the humus content at the level of a strong relationship was revealed. The content of N-NH4 in the soil reduced its value. With an increase in the capacity of cation exchange, the value of this parameter changed, passing through the maximum, pHKCl - through the minimum. Changes in the humus content and physico-chemical properties of soil differences of gray forest soils have been established: gray forest plakornaya, gray forest medium-saline, gray forest medium-saline with a second humus horizon.

Influence of landscape features on urban land surface temperature: Scale and neighborhood effects

Higher land surface temperature (LST) in cities than its surrounding areas presents a major sustainability challenge for cities. Adaptation and mitigation of the increased LST require in-depth understanding of the impacts of landscape features on LST. We studied the influences of different landscape features on LST in five large cities across China to investigate how the features of a specific urban landscape (endogenous features), and neighboring environments (exogenous features) impact its LST across a continuum of spatial scales. Surprisingly, results show that the influence of endogenous landscape features (Eendo) on LST can be described consistently across all cities as a nonlinear function of grain size (gs) and neighbor size (ns) (Eendo = βnsgs-0.5, where β is a city-specific constant) while the influence of exogenous features (Eexo) depends only on neighbor size (ns) (Eexo = γ-εns0.5, where γ and ε are city-specific constants). In addition, a simple relationship describing the relative strength of endogenous and exogenous impacts of landscape features on LST was found (Eendo > Eexo if ns > kgs2/5, where k is a city-specific parameter; otherwise, Eendo < Eexo). Overall, vegetation alleviates 40%–60% of the warming effect of built-up while surface wetness intensifies or reduces it depending on climate conditions. This study reveals a set of unifying quantitative relationships that effectively describes landscape impacts on LST across cities, grain and neighbor sizes, which can be instrumental towards the design of sustainable cities to deal with increasing temperature.

Implications of landscape genetics and connectivity of snow leopard in the Nepalese Himalayas for its conservation

The snow leopard is one of the most endangered large mammals. Its population, already low, is declining, most likely due to the consequences of human activity, including a reduction in the size and number of suitable habitats. With climate change, habitat loss may escalate, because of an upward shift in the tree line and concomitant loss of the alpine zone, where the snow leopard lives. Migration between suitable areas, therefore, is important because a decline in abundance in these areas may result in inbreeding, fragmentation of populations, reduction in genetic variation due to habitat fragmentation, loss of connectivity, bottlenecks or genetic drift. Here we use our data collected in Nepal to determine the areas suitable for snow leopards, by using habitat suitability maps, and describe the genetic structure of the snow leopard within and between these areas. We also determine the influence of landscape features on the genetic structure of its populations and reveal corridors connecting suitable areas. We conclude that it is necessary to protect these natural corridors to maintain the possibility of snow leopards’ migration between suitable areas, which will enable gene flow between the diminishing populations and thus maintain a viable metapopulation of snow leopards.

Effects of human-related and biotic landscape features on the occurrence and size of modern forest fires in Sweden

The influence of landscape features on the occurrence and size of forest fires in Northern Europe has not been well-studied. In this paper, we analyzed the impact of human-related landscape properties (road and human population density), biotic features (amount of firebreak area and vegetation zone) and fire weather indices (Buildup Index, BUI and Initial Spread Index, ISI) on the occurrence and size of forest fires in Sweden from 1998 to 2017. To analyze the environmental controls of fire occurrence and fire size under different levels of climatological fire hazard, we divided the data into two subsets: (1) large fire years (LFY), defined as the years with the total amount of burned area being higher than the dataset-wide average (2002, 2003, 2006, 2008 and 2014), and (2) the remaining years (nLFY). Our analytical approach was based on spatial models using Integrated Nested Laplace Approximations (INLA). Models built on both LFY and nLFY subsets suggested a strong human influence on fire occurrence: road density, the number of firebreaks, and population density, all were positively associated with fire occurrence, suggesting an important role of human-related ignitions. The southernmost vegetation zones in Sweden (boreo-nemoral and nemoral) exhibited the highest fire occurrence (LFY), a pattern potentially related to a higher population density in combination with weather more conducive for fires in this part of the country. The patterns that emerged from the fire size models pointed to the climate as the main factor controlling fire size, irrespective of the type of years analyzed. Road density, number of firebreaks and population density showed a negative association with fire size, possibly indicating higher efficiency of fire suppression in the areas with higher human presence. Vegetation zones were selected as an informative predictor, indicating that the fire activity varies across the zones, with those in mid-Sweden being the most prone to large events. The ISI correlated strongly and positively with fire size in both subsets (LFY and nLFY), pointing to the role of weather conditions favorable for fire spread, primarily that of surface fires. The BUI showed a weak negative correlation to fire size, indicating that dryness of organic horizon, specifically its deeper layers, is less relevant for predicting fire size. Contemporary fire activity in Sweden is driven by a combination of human-related ignitions, and weather conditions controlling fire spread with a moderate effect of vegetation composition and generally efficient fire suppression. Human-related landscape features (roads and population density) play a major role in shaping ignition patterns, whereas climate (ISI) and vegetation properties appear informative as predictors of fire size, even under a modern fire suppression effort.

Assessing the effect of landscape features on pond colonisation by an elusive amphibian invader using environmental DNA

Abstract Environmental DNA (eDNA) is becoming an essential tool for detecting aquatic invasive species and investigating their spread. Surprisingly, this technique has been very rarely used to investigate habitat selection, site occupancy, and colonisation despite its higher capacity to detect many species. The African clawed frog (Xenopus laevis) is a principally aquatic amphibian introduced in several continents from South Africa. In western France, no recent systematic survey of the invasion range has been attempted, mainly because of the elusive nature of the species. Furthermore, the influence of landscape features on invasion has never been investigated, even if adults and juveniles are known to disperse overland and along river networks. Using presence–absence data generated by an eDNA survey conducted across the known invasion front of X. laevis in western France, we aimed to determine whether and how the landscape features surrounding a pond influence the probability that a pond is colonised. Xenopus laevis was detected well beyond the formerly known invasive distribution and at the outward end of some transects, suggesting that we did not reach the actual invasion front in these parts of the range. The landscape variables that best predicted the presence of X. laevis in a pond were topographic wetness index and grass cover within a buffer of 250 m. Higher values of both topographic wetness index and grass cover were negatively related to the occurrence probability. The effects of these two variables more likely to reflect dispersal behaviour than habitat preferences at the pond scale. By combining the high detection probability of eDNA survey techniques and a landscape ecology approach, we may gain valuable insight into the colonisation process of water bodies by elusive invasive species. Such information is crucial to prevent access to specific sites and locate invasion front areas where connectivity can be disrupted, thus increasing the effectiveness of management countermeasures.

Influences of Landscape Features on Bat Activity in North Dakota

ABSTRACTLand conversion and modification threatens many wildlife and plant species in the northern Great Plains, including bats. Our objective was to assess the association of bat species with landscape features in the northern Great Plains of North Dakota, USA, taking the first step towards understanding the habitat needs of bats in this region. We examined patterns of bat activity across different landscapes, identified those landscape features associated with high levels of bat activity, and determined which specific land features (i.e., vegetation and water types) were most commonly associated with each bat species. We used passive acoustic monitoring to measure bat activity at sites across North Dakota, and assessed detailed land characteristics at each site. We used nonmetric multidimensional scaling and multivariate regression tree analysis to examine relationships between bat activity and landscape variables. Bat foraging activity was influenced by structural landscape characteristics and the availability of specific water resources. High levels of bat activity were associated with riparian forested areas of varying structural complexity, ponds, and, to a lesser extent, open riparian lands. Individual bat species were influenced by land type and water resources differently. We identified big brown bats (Eptesicus fuscus) and little brown bats (Myotis lucifugus) as indicators of open riparian and pond landscapes, respectively. These results highlight the importance of prairie riparian landscapes and maintaining heterogeneity across the landscape for conservation and management of bat communities. Further, we identified ponds as an important landscape feature for little brown bats, a species of conservation concern, indicating that this specific feature should be a focus of conservation efforts on prairie wetlands. © 2019 The Wildlife Society.

Influence of landscape features on the large variation of shallow groundwater salinity in southwestern Bangladesh

In southwestern Bangladesh, the large variation in groundwater salinity has only been elucidated in small-scale study areas and along large regional-scale gradients. We aimed to assess the regional shallow (<60 m) groundwater salinity variation with a higher resolution as a function of landscape features and associated hydrological processes. Spatial variation in groundwater salinity was assessed using 442 EC measurements from previous studies and 1998 new EC measurements. Groundwater EC values were correlated with well location data (latitude, longitude and depth of the filter) and landscape feature data (elevation, soil type, land use and surface clay thickness). Additionally, we performed a geomorphological analysis of landscape features to infer associated hydrological processes. We interpret wide fluvial zones to be remnants of sandy deposits in large paleo channels which allow freshwater recharge, resulting in groundwater that is mostly (75%) fresh. Narrow fluvial zones, tidal fluvial zones, and fluvial zones next to tidal rivers are more susceptible to lateral saline water flow or saline water recharge by occasional tidal flooding, and only contain some shallow fresh groundwater in high-lying zones. Tidal flat or tidal fringe zones hardly contain any fresh groundwater. This study is the first to demonstrate the relation between landscape features, hydrological processes and regional groundwater salinity throughout southwestern Bangladesh. The main lines of our approach may be applicable in other coastal areas with available spatial landscape feature data, enabling a first prediction of groundwater salinity variation.

Sampling related individuals within ponds biases estimates of population structure in a pond-breeding amphibian.

Effective conservation and management of pond‐breeding amphibians depends on the accurate estimation of population structure, demographic parameters, and the influence of landscape features on breeding‐site connectivity. Population‐level studies of pond‐breeding amphibians typically sample larval life stages because they are easily captured and can be sampled nondestructively. These studies often identify high levels of relatedness between individuals from the same pond, which can be exacerbated by sampling the larval stage. Yet, the effect of these related individuals on population genetic studies using genomic data is not yet fully understood. Here, we assess the effect of within‐pond relatedness on population and landscape genetic analyses by focusing on the barred tiger salamanders (Ambystoma mavortium) from the Nebraska Sandhills. Utilizing genome‐wide SNPs generated using a double‐digest RADseq approach, we conducted standard population and landscape genetic analyses using datasets with and without siblings. We found that reduced sample sizes influenced parameter estimates more than the inclusion of siblings, but that within‐pond relatedness led to the inference of spurious population structure when analyses depended on allele frequencies. Our landscape genetic analyses also supported different models across datasets depending on the spatial resolution analyzed. We recommend that future studies not only test for relatedness among larval samples but also remove siblings before conducting population or landscape genetic analyses. We also recommend alternative sampling strategies to reduce sampling siblings before sequencing takes place. Biases introduced by unknowingly including siblings can have significant implications for population and landscape genetic analyses, and in turn, for species conservation strategies and outcomes.

Combining familiarity and landscape features helps break down the barriers between movements and home ranges in a non-territorial large herbivore.

Recent advances in animal ecology have enabled identification of certain mechanisms that lead to the emergence of territories and home ranges from movements considered as unbounded. Among them, memory and familiarity have been identified as key parameters in cognitive maps driving animal navigation, but have been only recently used in empirical analyses of animal movements. At the same time, the influence of landscape features on movements of numerous species and on space division in territorial animals has been highlighted. Despite their potential as exocentric information in cognitive maps and as boundaries for home ranges, few studies have investigated their role in the design of home ranges of non-territorial species. Using step selection analyses, we assessed the relative contribution of habitat characteristics, familiarity preferences and linear landscape features in movement step selection of 60 GPS-collared Mediterranean mouflon Ovis gmelini musimon × Ovis sp. monitored in southern France. Then, we evaluated the influence of these movement-impeding landscape features on the design of home ranges by testing for a non-random distribution of these behavioural barriers within sections of space differentially used by mouflon. We reveal that familiarity and landscape features are key determinants of movements, relegating to a lower level certain habitat constraints (e.g. food/cover trade-off) that we had previously identified as important for this species. Mouflon generally avoid crossing both anthropogenic (i.e. roads, tracks and hiking trails) and natural landscape features (i.e. ridges, talwegs and forest edges) while moving in the opposite direction, preferentially toward familiar areas. These specific behaviours largely depend on the relative position of each movement step regarding distance to the landscape features or level of familiarity in the surroundings. We also revealed cascading consequences on the design of home ranges in which most landscape features were excluded from cores and relegated to the peripheral areas. These results provide crucial information on landscape connectivity in a context of marked habitat fragmentation. They also call for more research on the role of landscape features in the emergence of home ranges in non-territorial species using recent methodological developments bridging the gap between movements and space use patterns.

Influence of landscape features on the location of grey heron Ardea cinerea colonies in Poland

We analysed hydrographic and habitat factors influencing the location of 207 colonies of the grey heron Ardea cinerea in Poland. We compared areas of particular habitats in three buffers around colonies (0–1, 0–10, 0–20km) among eight regions differing in their proportions of studied habitats. We found the highest inter-region dissimilarities in areas covered by water bodies (all scales) and pastures (0–1km). We recognized some indicator habitats characteristic of the majority (water bodies, pastures) or of some (seacoast, inland marshes, urbanized zone) regions. The habitat selectivity index showed that grey herons in buffer 0–1km preferred pastures and water bodies in seven regions and rivers in one subprovince. In buffer 0–10km, forests and urban zones were preferred in seven and five subprovinces, respectively. Our study revealed that both aquatic and non-aquatic habitats are important for the distribution of the grey heron colonies in Poland.

Influence of landscape features on the microgeographic genetic structure of a resident songbird.

Landscape features influence individual dispersal and as a result can affect both gene flow and genetic variation within and between populations. The landscape of British Columbia, Canada, is already highly heterogeneous because of natural ecological and geological transitions, but disturbance from human-mediated processes has further fragmented continuous habitat, particularly in the central plateau region. In this study, we evaluated the effects of landscape heterogeneity on the genetic structure of a common resident songbird, the black-capped chickadee (Poecile atricapillus). Previous work revealed significant population structuring in British Columbia that could not be explained by physical barriers, so our aim was to assess the pattern of genetic structure at a microgeographic scale and determine the effect of different landscape features on genetic differentiation. A total of 399 individuals from 15 populations were genotyped for fourteen microsatellite loci revealing significant population structuring in this species. Individual- and population-based analyses revealed as many as nine genetic clusters with isolation in the north, the central plateau and the south. Moreover, a mixed modelling approach that accounted for non-independence of pairwise distance values revealed a significant effect of land cover and elevation resistance on genetic differentiation. These results suggest that barriers in the landscape influence dispersal which has led to the unexpectedly high levels of population isolation. Our study demonstrates the importance of incorporating landscape features when interpreting patterns of population differentiation. Despite taking a microgeographic approach, our results have opened up additional questions concerning the processes influencing dispersal and gene flow at the local scale.

Habitat quality limits gene flow between populations of Bombus ruderatus in the South Island, New Zealand

One of the primary reasons for the decline of some bumblebee species has been habitat loss and fragmentation through land use change. Habitat fragmentation can limit connectivity between populations and gene flow between bumblebee populations can be limited by open water and human altered landscapes, however the influence of landscape features on gene flow has only been examined in non-declining species. The ruderal bumblebee, Bombus ruderatus, was successfully introduced to and is now relatively common in New Zealand, providing an opportunity to examine the biology of a species that is now rare in its native range in the UK. In this study, we examine the genetic structuring of B. ruderatus populations in the South Island of New Zealand and we demonstrate that a relatively simple classification of the landscape, into either good or poor foraging habitat at coarse resolution (800 m2), can predict levels of gene flow. We found populations of B. ruderatus as far apart as 160 km showing no significant genetic differentiation. However, this level of gene flow appears to be reliant upon continuous suitable habitat, as other populations <100 km apart were found to be significantly differentiated. These results suggest that corridors of continuous habitat are required to facilitate gene flow over large distances for this species.

The influence of landscape features on nest predation rates of grassland‐breeding waders

In Europe, lowland wet grasslands have become increasingly fragmented, and populations of waders in these fragments are subject to unsustainably high levels of nest predation. Patches of taller vegetation in these landscapes can support small mammals, which are the main source of prey for many predators. Providing such patches of habitat could potentially reduce levels of nest predation if predators preferentially target small mammals. However, predator attraction to patches of taller vegetation for foraging, shelter, perching and/or nesting could also result in local increases in predation rates, as a consequence of increased predator densities or spill‐over foraging into the surrounding area. Here we assess the influence of taller vegetation on wader nest predation rates, and the feasibility of managing vegetation structure to alter predator impacts. Between 2005 and 2011, the nest distribution and hatching success of Northern Lapwings Vanellus vanellus, which nest in the open, and Common Redshanks Tringa totanus, which conceal their nests in vegetation, were measured on a 487‐ha area of wet grassland in eastern England that is primarily managed for breeding waders. Predation rates of Lapwing nests increased significantly with distance from patches of taller vegetation, and decreased with increasing area of taller vegetation within 1 km of the nest, whereas neither variable influenced Redshank nest predation probability. These findings suggest that the distribution and activity of nest predators in lowland wet grassland landscapes may be influenced by the presence and distribution of areas of taller vegetation. For Lapwings at least, there may therefore be scope for landscape‐scale management of vegetation structure to influence levels of predation in these habitats.

Landscape influences on the natural and artificially manipulated movements of bearded capuchin monkeys

Cognitive mechanisms underlying the choice of movement patterns between resource sites for nonhuman primates are not well understood. Specifically, the influence of landscape features on decision making and spatial memory of naturally ranging animals has not been explicitly investigated. We evaluated three models of bearded capuchin monkey, Sapajus libidinosus, movement decisions that incorporated varying degrees of landscape and memory influences, and we conducted a field experiment using a novel call-back technique to test these influences. The movements and spatial decisions of the monkeys were modelled between temporal stop points and spatial change points during natural travel using straight-line path, a minimum-resistance path and landscape-perceiving path models. For these movement models, resistance was calculated as the inverse of habitat suitability, a surface based on the natural movement patterns of the study group. Of the three models, natural travel most closely resembled the straight-line path model in its landscape resistance, but not in its geometry. This result indicates that while the monkeys travel in zones of low resistance, they do not minimize distance or landscape resistance between travel nodes. When monkeys were called to an artificial resource site using the call-back experiment, their travel was more linear and higher in landscape resistance. The limited quantity and high quality of the food resource in the artificial resource sites may have influenced the nature of the monkeys' travel in these experiments. We present the advantages and challenges of the call-back method of experimental analysis of animal movement and we conclude that future analyses of spatial cognition should include consideration of landscape context.

Influence of landscape features on spatial genetic structure of white‐tailed deer in human‐altered landscapes

ABSTRACTPredictive relationships between estimates of functional population connectivity and physical and biotic landscape features can provide important insights into present and future population responses to human‐mediated landscape change. Quantification of associations between landscape features and dispersal or genetic surrogates such as gene flow among areas can be particularly challenging for continuously distributed and highly mobile wildlife species. We assessed the relative influence of natural and human‐altered landscape features on white‐tailed deer (Odocoileus virginianus) spatial genetic structure (SGS) in southern Michigan (USA) using 7 microsatellite markers assayed for 326 adult individuals from 21 contiguous counties (33,284 km2). We used previously collected telemetry data to quantify probabilities of habitat occupancy and seasonal movements that allowed selection and weighting of landscape features to create habitat suitability indices (HSI). We assigned individuals to groups (n = 13) for statistical analyses quantifying relationships between measures of SGS (response variable) with Euclidean distance, least cost distances parameterized using HSI, and presence of natural (rivers) and man‐made (roads) barriers to dispersal. Over the entire study area, genetic differentiation was significant (mean Fst = 0.019, P &lt; 0.001) and increased with increasing inter‐group geographic distance (r2 = 0.381; P &lt; 0.05). We identified features in the landscape matrix between groups including rivers, high traffic roads, and habitats of intermediate HSI as inhibiting gene flow. Low HSI was associated with low between‐group Fst and appeared to facilitate gene flow. Quantification of the relative importance of man‐made barriers (roads) and habitat suitability to SGS for white‐tailed deer emphasizes the importance of joint use of ecological and genetic analyses in conservation and control efforts for abundant and mobile wildlife species. © 2014 The Wildlife Society.

Comparative landscape genetics of two river frog species occurring at different elevations on Mount Kilimanjaro.

Estimating population connectivity and species' abilities to disperse across the landscape is crucial for understanding the long-term persistence of species in changing environments. Surprisingly, few landscape genetic studies focused on tropical regions despite the alarming extinction rates within these ecosystems. Here, we compared the influence of landscape features on the distribution of genetic variation of an Afromontane frog, Amietia wittei, with that of its more broadly distributed lowland congener, Amietia angolensis, on Mt. Kilimanjaro, Tanzania. We predicted high gene flow in the montane species with movements enhanced through terrestrial habitats of the continuous rainforest. In contrast, dispersal might be restricted to aquatic corridors and reduced by anthropogenic disturbance in the lowland species. We found high gene flow in A. wittei relative to other montane amphibians. Nonetheless, gene flow was lower than in the lowland species which showed little population structure. Least-cost path analysis suggested that dispersal is facilitated by stream networks in both species, but different landscape features were identified to influence connectivity among populations. Contrary to a previous study, gene flow in the lowland species was negatively correlated with the presence of human settlements. Also, genetic subdivision in A. wittei did not coincide with specific physical barriers as in other landscape genetic studies, suggesting that factors other than topography may contribute to population divergence. Overall, these results highlight the importance of a comparative landscape genetic approach for assessing the influence of the landscape matrix on population connectivity, particularly because nonintuitive results can alter the course of conservation and management.

Downscaling MODIS LST in the East African mountains using elevation gradient and land-cover information

Land-surface temperature (LST) is strongly affected by altitude and surface albedo. In mountain regions where steep slopes and heterogeneous land cover are predominant, LST can vary significantly within short distances. Although remote sensing currently provides opportunities for monitoring LST in inaccessible regions, the coarse resolution of some sensors may result in large uncertainties at sub-pixel scales. This study aimed to develop a simple methodology for downscaling 1 km Moderate Resolution Spectroradiometer (MODIS) LST pixels, by accounting for sub-pixel LST variation associated with altitude and land-cover spatial changes. The approach was tested in Mount Kilimanjaro, Tanzania, where changes in altitude and vegetation can take place over short distances. Daytime and night-time MODIS LST estimates were considered separately. A digital elevation model (DEM) and normalized difference vegetation index (NDVI), both at 250 m spatial resolution, were used to assess altitude and land-cover changes, respectively. Simple linear regressions and multivariate regressions were used to quantify the relationship between LST and the independent variables, altitude and NDVI. The results show that, in Kilimanjaro, altitude variation within the area covered by a 1 km MODIS LST pixel can be up to ±300 m. These altitude changes can cause sub-pixel variation of up to ±2.13°C for night-time and ±2.88°C for daytime LST. NDVI variation within 1 km pixels ranged between –0.2 and 0.2. For night-time measurements, altitude explained up to 97% of LST variation, while daytime LST was strongly affected by land cover. Using multivariate regressions, the combination of altitude and NDVI explained up to 94% of daytime LST variation in Kilimanjaro. Finally, the downscaling approach proposed in this study allowed an improved representation of the influence of landscape features on local-scale LST patterns.