Climate and land-use change have led to disturbance regimes in many ecosystems without a historical analog, leading to uncertainty about how species adapted to past conditions will respond to novel post-disturbance landscapes.
ObjectivesWe examined habitat selection by spotted owls in a post-fire landscape. We tested whether selection or avoidance of severely burned areas could be explained by patch size or configuration, and whether variation in selection among individuals could be explained by differences in habitat availability.
MethodsWe applied mixed-effects models to GPS data from 20 spotted owls in the Sierra Nevada, California, USA, with individual owls occupying home ranges spanning a broad range of post-fire conditions after the 2014 King Fire.
ResultsIndividual spotted owls whose home ranges experienced less severe fire (<?5% of home range severely burned) tended to select severely burned forest, but owls avoided severely burned forest when more of their home range was affected (~ 5–40%). Owls also tended to select severe fire patches that were smaller in size and more complex in shape, and rarely traveled?>?100-m into severe fire patches. Spotted owls avoided areas that had experienced post-fire salvage logging but the interpretation of this effect was nuanced. Owls also avoided areas that were classified as open and/or young forest prior to the fire.
ConclusionsOur results support the hypothesis that spotted owls are adapted to historical fire regimes characterized by small severe fire patches in this region. Shifts in disturbance regimes that produce novel landscape patterns characterized by large, homogeneous patches of high-severity fire may negatively affect this species.
相似文献Conservation for the Indiana bat (Myotis sodalis), a federally endangered species in the United States of America, is typically focused on local maternity sites; however, the species is a regional migrant, interacting with the environment at multiple spatial scales. Hierarchical levels of management may be necessary, but we have limited knowledge of landscape-level ecology, distribution, and connectivity of suitable areas in complex landscapes.
ObjectivesWe sought to (1) identify factors influencing M. sodalis maternity colony distribution in a mosaic landscape, (2) map suitable maternity habitat, and (3) quantify connectivity importance of patches to direct conservation action.
MethodsUsing 3 decades of occurrence data, we tested a priori, hypothesis-driven habitat suitability models. We mapped suitable areas and quantified connectivity importance of habitat patches with probabilistic habitat availability metrics.
ResultsFactors improving landscape-scale suitability included limited agriculture, more forest cover, forest edge, proximity to medium-sized water bodies, lower elevations, and limited urban development. Areas closer to hibernacula and rivers were suitable. Binary maps showed that 30% of the study area was suitable for M. sodalis and 29% was important for connectivity. Most suitable patches were important for intra-patch connectivity and far fewer contributed to inter-patch connectivity.
ConclusionsWhile simple models may be effective for small, homogenous landscapes, complex models are needed to explain habitat suitability in large, mixed landscapes. Suitability modeling identified factors that made sites attractive as maternity areas. Connectivity analysis improved our understanding of important areas for bats and prioritized areas to target for restoration.
相似文献Landscape and local habitat traits moderate wild bee communities. However, whether landscape effects differ between local habitat types is largely unknown.
ObjectivesWe explored the way that wild bee communities in three distinct habitats are shaped by landscape composition and the availability of flowering plants by evaluating divergences in response patterns between habitats.
MethodsIn a large-scale monitoring project across 20 research areas, wild bee data were collected on three habitats: near-natural grassland, established flower plantings and residual habitats (e.g. field margins). Additionally, landscape composition was mapped around the research areas.
ResultsOur monitoring produced a dataset of 27,650 bees belonging to 324 species. Bee communities on all three habitats reacted similarly to local flower availability. Intensively managed grassland in the surrounding landscape had an overall negative effect on the studied habitats. Other landscape variables produced diverging response patterns that were particularly pronounced during early and late season. Bee communities in near-natural grassland showed a strong positive response to ruderal areas. Flower plantings and residual habitats such as field margins showed a pronounced positive response to extensively managed grassland and woodland edges. Response patterns regarding bee abundance were consistent with those found for species richness.
ConclusionWe advise the consideration of local habitat type and seasonality when assessing the effect of landscape context on bee communities. A reduction in the intensity of grassland management enhances bee diversity in a broad range of habitats. Moreover, wild bee communities are promoted by habitat types such as ruderal areas or woodland edges.
相似文献Artificial light at night (ALAN) provides an array of important benefits but might also adversely affect humans and other living organisms. Yet, the existing reviews of accumulated knowledge about the multifaceted effects associated with exposure to ALAN focus on distinct ecosystem components. As a result, our understanding of potential system-wide impacts of ALAN exposure is insufficient.
ObjectivesThis paper attempts to bridge this knowledge gap by reviewing a wide range of studies, with a particular focus on identifying the impacts of ALAN exposure that are common to different species.
MethodsThe survey is conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and covers peer-reviewed articles published from 2000 to 2019.
ResultsSeventy-four eligible articles, out of 1223 initially identified, were selected and synthesized. 20% of them focus on humans, while the rest explore other living organisms, such as vertebrates, avian species, arthropods, aquatic organisms, and vegetation. The review demonstrates that similar adverse effects of ALAN exposure, ranging from sleep disturbance, depression, weight gain, eating and movement disorders, to elevated risk of cancer, are manifested across different components of the ecosystem, and therefore entail wider and more complex risks to its stability and integrity.
ConclusionTo reduce ecosystem risks, associated with constantly increasing ALAN levels, illumination policies should be based on directional and reduced nighttime lighting, which can help to avoid unnecessary exposures. The study highlights knowledge gaps that warrant further research attention.
相似文献Context
Testing the influence of edges on animal distributions depends on our capacity to quantify ‘edge’, particularly in heterogeneous landscapes. Habitat quality is likely to differ in instances where edges are abrupt and anthropogenic in origin, versus diffuse, disturbance-created edges.Objectives
We tested whether or not structurally distinct edge types influence northern spotted owl habitat selection and whether the relationship between edge type and use varied across spatial scales relevant to owl foraging (<3 ha) and home range selection (50–800 ha).Methods
We used remotely sensed disturbance severity data to define two distinct edge types, ‘hard’ and ‘diffuse’, following a 11,000 ha fire and subsequent salvage logging in southern Oregon. The approach quantifies the steepness of gradients directly by measuring the ‘slope’ of change in disturbance severity. We tested the degree to which 23 radio-collared spotted owls responded to edge characteristics caused by fire and logging.Results
Spotted owls showed a strong negative association with hard edge, even after accounting for habitat suitability and other confounding variables. However, this negative relationship was highly scale-dependent; spotted owls were resilient to hard edges at broad scales, but avoided the same feature at fine scales. On the other hand, spotted owls showed a positive association with diffuse edge, especially at broader scales.Conclusions
Differential use of edge types indicates that owls favor disturbances that create diffuse edge habitat (e.g. low and mixed-severity fire) and rather than abrupt boundaries created by high severity disturbance.Context
Conservation planning for at-risk species requires understanding of where species are likely to occur, how many individuals are likely to be supported on a given landscape, and the ability to monitor those changes through time.Objectives
We developed a distribution model for northern spotted owls that incorporates both habitat suitability and probability of territory occupancy while accounting for interspecies competition.Methods
We developed range-wide habitat suitability maps for two time periods (1993 and 2012) for northern spotted owls that accounted for regional differences in habitat use and home range size. We used these maps for a long-term demographic monitoring study area to assess habitat change and estimate the number of potential territories based on available habitat for both time periods. We adjusted the number of potential territories using known occupancy rates to estimate owl densities for both time periods. We evaluated our range-wide habitat suitability model using independent survey data.Results
Our range-wide habitat maps predicted areas suitable for territorial spotted owl presence well. On the demographic study area, the amount of habitat declined 19.7% between 1993 and 2012, while our estimate of the habitat-based carrying capacity declined from 150 to 146 territories. Estimated number of occupied territories declined from 94 to 57.Conclusions
Conservation and recovery of at-risk species depends on understanding how habitat changes over time in response to factors such as wildfire, climate change, biological invasions, and interspecies competition, and how these changes influence species distribution. We demonstrate a model-based approach that provides an effective planning tool.Forest management and disturbances cause habitat fragmentation for saproxylic species living on old-growth attributes. The degree of habitat spatiotemporal continuity required by these species is a key question for designing biodiversity-friendly forestry, and it strongly depends on species’ dispersal. The “stability–dispersal” model predicts that species using stable habitats should have lower dispersal abilities than species associated with ephemeral habitat and thus respond to habitat availability at smaller scales.
ObjectivesWe aimed at testing the stability–dispersal model by comparing the spatial scales at which saproxylic beetle guilds using substrates with contrasted stability (from stable to ephemeral: cavicolous, fungicolous, saproxylophagous and xylophagous guilds) are affected by landscape structure (i.e. habitat amount and aggregation).
MethodsWe sampled saproxylic beetles using a spatially nested design (plots within landscape windows). We quantified habitat availability (tree cavities, polypores and deadwood) in 1-ha plots, 26-ha buffers around plots and 506-ha windows, and analyzed their effect on the abundance and diversity of associated guilds.
ResultsThe habitat amount within plots and buffers positively affected the abundance of the cavicolous and the fungicolous guilds whereas saproxylophagous and xylophagous did not respond at these scales. The habitat aggregation within windows only positively affected the saproxylophagous species richness within plots and also on the similarity in species composition among plots.
ConclusionsBeetle guilds specialized on more stable habitat were affected by landscape structure at smaller spatial scales, which corroborated the stability–dispersal model. In managed forests, the spatial grain of conservation efforts should therefore be adapted to the target habitat lifetime.
相似文献Urbanization is a substantial force shaping the genetic and demographic structure of natural populations. Urban development and major highways can limit animal movements, and thus gene flow, even in highly mobile species. Characterizing varying species responses to human activity and fragmentation is important for maintaining genetic continuity in wild animals and for preserving biodiversity. As one of the only common and wide-ranging large wild herbivores in much of urban North America, deer play an important ecological role in urban ecosystems, yet the genetic impacts of development on deer are not well known.
ObjectivesWe assessed genetic connectivity for mule deer to understand their genetic response to habitat fragmentation, due to development and highway barriers, in an increasingly urbanized landscape.
MethodsUsing non-invasive sampling across a broad region of southern California, we investigated genetic structure among several natural areas that were separated by major highways and applied least-cost path modelling to determine if landscape context and highway attributes influence genetic distance for mule deer.
ResultsWe observed significant yet variable differentiation between subregions. We show that genetic structure corresponds with highway boundaries in certain habitat patches, and that particular landscape configurations more greatly limit gene flow between patches.
ConclusionsAs a large and highly mobile species generally considered to be well adapted to human activity, mule deer nonetheless showed genetic impacts of intensive urbanization. Because of this potential vulnerability, mule deer and other ungulates may require further consideration for effective habitat management and maintenance of landscape connectivity in human-dominated landscapes.
相似文献Urbanization can affect the density of hosts, altering patterns of infection risk in wildlife. Most studies examining associations between urbanization and host-parasite interactions have focused on vertebrate wildlife that carry zoonotic pathogens, and less is known about responses of other host taxa, including insects.
ObjectivesHere we ask whether urban development predicts infection by a protozoan, Ophyrocystis elektroscirrha, in three populations of monarchs (Danaus plexippus): migratory monarchs in northeastern U.S., non-migratory monarchs in southeastern coastal U.S., and non-migratory monarchs in Hawaii.
MethodsWe used impervious surface and developed land cover classes from the National Land Cover Database to derive proportional measures of urban development and an index of land cover aggregation at two spatial scales. Parasite data were from previous field sampling (Hawaii) and a citizen science project focused on monarch infection in North America.
ResultsProportional measures of urban development predicted greater infection prevalence for non-migratory monarchs sampled in the southern coastal U.S. and Hawaii, but not in the northern U.S. Aggregations of low intensity development, dominated by single-family housing, predicted greater infection prevalence in monarchs from the northern and southern coastal U.S. populations, but predicted lower infection prevalence in Hawaii.
ConclusionsBecause natural habitats have been reduced by land-use change, plantings for monarchs in residential areas and urban gardens has become popular among the public. Mechanisms that underlie higher infection prevalence in urban landscapes remain unknown. Further monitoring and experimental studies are needed to inform strategies for habitat management to lower infection risk for monarchs.
相似文献Habitat characteristics are often equated with habitat function for animals. However, in heterogeneous landscapes, similar habitat types occur in different environmental contexts. In the marine realm, landscape studies have been confined to particular environments, rather than encompassing entire seascapes, due to incompatible sampling methods required in different situations.
ObjectivesWe examined the interactive structuring effects of local habitat characteristics and environmental context on assemblage composition.
MethodsWe used a single technique—remote underwater video census—to explore the importance of habitat type (biotic structural components, substrate, and depth) and environmental context (marine vs estuarine) in structuring juvenile fish assemblages throughout an entire coastal region. In this model system, a range of structural habitat types were present in both estuarine and marine contexts.
ResultsThe 1315 video surveys collected show a clear hierarchy in the organisation of juvenile fish communities, with assemblages first distinguished by environmental context, then by habitat type. Marine and estuarine mangroves contained entirely different assemblages, and likewise for rocky reefs and submerged aquatic vegetation. Our results suggest that two functionally different ‘seascape nursery’ types exist at local scales within a single region, defined by their context.
ConclusionsThe context of a location can be of greater significance in determining potential habitat function than what habitat-forming biota and substrates are present, and apparently similar habitat types in different contexts may be functionally distinct. These findings have important implications for local-scale management and conservation of juvenile fish habitats, particularly in regard to offsetting and restoration.
相似文献Landscape geodiversity, and in particular small natural features (SNF), are crucial components of habitat suitability for many threatened species. Rocky cliffs at the sea-continent interface present complex small-scale geomorphologies which are exploited by nesting seabirds.
ObjectivesElucidation of the relation between nest-site geomorphology and species preference in cliff-nesting seabirds. Evaluation of the potential of cliff-face SNF as seabird conservation tools.
MethodsNest site geomorphological characteristics of four Atlantic (Brittany, France) cliff-dwelling seabirds (Razorbill, Guillemot, Fulmar, and Kittiwake) were categorized, and scored for degree of enclosure.
ResultsOf the 1048 nest sites examined, the greatest species overlap in location was the mid-region of the cliff face: Fulmar was concentrated in the upper half of the cliff, while Kittiwake showed the most extended vertical distribution. A distinct trend was evident with respect to ceiling presence and size: Razorbill?+?Kittiwake?>?Guillemot?>?Fulmar. Clear trends were also evident in ceiling inclination, ledge size, and side wall presence and inclination. A distinct ‘degree of enclosure’ hierarchy was documented, consolidated with the addition of sympatric species known for their extreme preferences: Atlantic Gannets and Guillemots at the extreme ‘open’ end, and Puffins and Storm Petrels at the extreme ‘closed’ end. Some plasticity in site choice was observed, probably corresponding to sub-optimal default choices.
ConclusionsDespite some plasticity, both vertical level and enclosure characteristics are associated with particular seabird species. Given the importance of nesting sites to seabird reproduction, the identification and conservation of these SNF constitute crucial conservation objectives.
相似文献Modifications in natural landcover generally result in a loss of habitat availability for wildlife and it’s persistence will depend largely on their spatial configuration and functional connections. Argenteohyla siemersi is a threatened and endemic amphibian whose habitat is composed of forest patches near rivers and water bodies edges.
ObjectivesThis study aimed to analyse the accessible habitat for this species and identify key elements to maintain its ecological network in two different types of land uses: an anthropized area with extensive cattle raising and a protected area.
MethodsThe structural and functional characteristics of both landscapes were analyzed. The connectivity at landscape level and the contribution of each habitat patch were evaluated through simulation models with different dispersion distances in the context of the graph theory.
ResultsIn both landscapes, nine types of landcover were identified with different compositions. Remarkable differences were found in habitat connectivity for this amphibian species between both landscapes. As the percentage of dispersion distance increases, reachable habitat increases as well, although with higher percentages in the protected area. Two corridors were identified in the protected landscape and one in the rangeland one; patches and key links constituted all of them.
ConclusionsThe present work provides spatially explicit results with a quantitative basis. It could be useful as a tool for the development of management plans aimed at guaranteeing the functionality of the ecological network for this endangered species and, therefore, contribute to its long-term conservation.
相似文献Black bear connectivity studies are scarce in the southern distribution where the species is endangered. The identification of corridors is a strategy to promote conservation in human-modified landscapes.
ObjectivesAssess and validate long-distance corridors in the southern black bear distribution using resistance models, occurrence records, and radio-telemetry of an individual that dispersed between the Sierras Madres of Mexico.
MethodsWe acquired black bear occurrence records from several sources and telemetry records from one dispersal individual in northern Mexico. We generated ensemble habitat suitability models and resistance landscape surfaces to generate cumulative resistant kernel and least-cost paths to identify connectivity core areas and corridors of importance through Natural Protected Areas. Finally, we assessed long-distance corridors.
ResultsWe developed three habitat suitability models for black bears southern range; one matches the current distribution of the species. When including radio-tracking records, the landscape resistance is reduced to arid sites with low habitat suitability. We used least resistance connectivity surfaces to merge subpopulations within each Sierra Madre. The long-distance corridor models indicate narrow routes that require individuals with plastic behavioral dispersal capacity. Almost 20% of the connectivity core areas are within Natural Protected Areas. These are the first large-scale corridors using resistance layers in the southern black bear distribution.
ConclusionsCorridors can be functional for a range of temperate and dry habitat species. Landscape connectivity models should include the monitoring of dispersal individuals to identify the plasticity of organisms and the tangible barriers for them.
相似文献Animal population dynamics are shaped by their movement decisions in response to spatial and temporal resource availability across landscapes. The sporadic availability and diversity of resources can create highly dynamic systems. This is especially true in agro-ecological landscapes where the dynamic interplay of insect movement and heterogeneous landscapes hampers prediction of their spatio-temporal dynamics and population size.
ObjectivesWe therefore systematically looked at population-level consequences of different movement strategies in temporally-dynamic resource landscapes for an insect species whose movement strategy is slightly understood: the Queensland Fruit Fly (Bactrocera tryoni)
MethodsWe developed a spatially-explicit model to predict changes in population dynamics and sizes in response to varying resources across a landscape. We simulated the temporal dynamics of fruit trees as the main resource using empirical fruiting dates. Movement strategies were derived from general principles and varied in directedness of movement and movement trigger.
ResultsWe showed that temporal continuity in resource availability was the main contributing factor for large and persistent populations. This explicitly included presence of continuous low-density resources such as fruit trees in urban areas. Analysing trapping data from SE Australia supported this finding. We also found strong effects of movement strategies, with directed movement supporting higher population densities.
ConclusionsThese results give insight into structuring processes of spatial population dynamics of Queensland Fruit Fly in realistic and complex food production landscapes, but can also be extended to other systems. Such mechanistic understanding will help to improve forecasting of spatio-temporal hotspots and bottlenecks and will, in the end, enable more targeted population management.
相似文献Context
Organisms commonly respond to their environment across a range of scales, however many habitat selection studies still conduct selection analyses using a single-scale framework. The adoption of multi-scale modeling frameworks in habitat selection studies can improve the effectiveness of these studies and provide greater insights into scale-dependent relationships between species and specific habitat components.Objectives
Our study assessed multi-scale nest/roost habitat selection of the federally “Threatened” Mexican spotted owl (Strix occidentalis lucida) in northern Arizona, USA in an effort to provide improved conservation and management strategies for this subspecies.Methods
We conducted multi-scale habitat modeling to assess habitat selection by Mexican spotted owls using survey data collected by the USFS. Each selected covariate was included in multi-scale models at their “characteristic scale” and we used an all-subsets approach and model selection framework to assess habitat selection.Results
The “characteristic scale” identified for each covariate varied considerably among covariates and results from multi-scale models indicated that percent canopy cover and slope were the most important covariates with respect to habitat selection by Mexican spotted owls. Multi-scale models consistently outperformed their analogous single-scale counterparts with respect to the proportion of deviance explained and model predictive performance.Conclusions
Efficacy of future habitat selection studies will benefit by taking a multi-scale approach. In addition to potentially providing increased explanatory power and predictive capacity, multi-scale habitat models enhance our understanding of the scales at which species respond to their environment, which is critical knowledge required to implement effective conservation and management strategies.Functional connectivity of semiaquatic species is poorly studied despite that freshwater ecosystems are amongst the most threatened worldwide due to habitat deterioration. The Neotropical otter, Lontra longicaudis, is a threatened species that represents a good model to evaluate the effect of landscape-riverscape features on genetic structure and gene flow of freshwater species.
ObjectivesWe aimed to assess the spatial genetic structure of L. longicaudis and to evaluate the landscape-riverscape attributes that shape its genetic structure and gene flow at local sites (habitat patches) and between sites (landscape matrix).
MethodsWe conducted the study in three basins located in Veracruz, Mexico, which have a high degree of ecosystem deterioration. We used a non-invasive genetic sampling and a landscape genetics individual-based approach to test the effect stream hierarchical structure, isolation-by-distance, and isolation-by-resistance on genetic structure and gene flow.
ResultsWe found genetic structure that corresponded to the latitudinal and altitudinal heterogeneity of the landscape and riverscape, as well as to the hierarchical structure of the streams. Open areas and steep slopes were the variables affecting genetic structure at local sites, whereas areas with suitable habitat conditions, higher ecosystem integrity and larger streams enhanced gene flow between sites.
ConclusionsThe landscape-riverscape characteristics that maintain functional connectivity of L. longicaudis differed between the upper, middle, and lower basins. Our results have important implications for the conservation of the species, including the maintenance of larger suitable areas in Actopan and the necessity to improve connectivity in Jamapa, through the establishment of biological corridors.
相似文献