Sensitivity of landscape resistance estimates based on point selection functions to scale and behavioral state: pumas as a case study

Estimating landscape resistance to animal movement is the foundation for connectivity modeling, and resource selection functions based on point data are commonly used to empirically estimate resistance. In this study, we used GPS data points acquired at 5-min intervals from radiocollared pumas in southern California to model context-dependent point selection functions. We used mixed-effects conditional logistic regression models that incorporate a paired used/available design to examine the sensitivity of point selection functions to the scale of available habitat and to the behavioral state of individual animals. We compared parameter estimates, model performance, and resistance estimates across 37 scales of available habitat, from 250 to 10,000 m, and two behavioral states, resource use and movement. Point selection functions and resistance estimates were sensitive to the chosen scale of the analysis. Multiple characteristic scales were found across our predictor variables, indicating that pumas in the study area are responding at different scales to different landscape features and that multi-scale models may be more appropriate. Additionally, point selection functions and resistance estimates were sensitive to behavioral state; specifically, pumas engaged in resource use behavior had an opposite selection response to some land cover types than pumas engaged in movement behavior. We recommend examining a continuum of scales and behavioral states when using point selection functions to estimate resistance.     

Estimating landscape resistance to movement: a review

Resistance surfaces are often used to fill gaps in our knowledge surrounding animal movement and are frequently the basis for modeling connectivity associated with conservation initiatives. However, the methods for quantifying resistance surfaces are varied and there is no general consensus on the appropriate choice of environmental data or analytical approaches. We provide a comprehensive review of the literature on this topic to highlight methods used and identify knowledge gaps. Our review includes 96 papers that parameterized resistance surfaces (sometimes using multiple approaches) for a variety of taxa. Data types used included expert opinion (n?=?76), detection (n?=?23), relocation (n?=?8), pathway (n?=?2), and genetic (n?=?28). We organized the papers into three main analytical approaches; one-stage expert opinion, one-stage empirical, and two-stage empirical, each of which was represented by 43, 22, and 36 papers, respectively. We further organized the empirical approaches into five main resource selection functions; point (n?=?16), matrix (n?=?38), home range (n?=?3), step (n?=?1), and pathway (n?=?1). We found a general lack of justification for choice of environmental variables and their thematic and spatial representation, a heavy reliance on expert opinion and detection data, and a tendency to confound movement behavior and resource use. Future research needs include comparative analyses on the choice of environmental variables and their spatial and thematic scales, and on the various biological data types used to estimate resistance. Comparative analyses amongst analytical processes is also needed, as well as transparency in reporting on uncertainty in parameter estimates and sensitivity of final resistance surfaces, especially if the resistance surfaces are to be used for conservation and planning purposes.     

The effect of roads on edge permeability and movement patterns for small mammals: a case study with Montane Akodont

Context

Increased edge density is among the main negative effects of habitat loss and fragmentation. Roads are linear infrastructures that may promote barrier effects due to disturbance and mortality effects. We hypothesized that edges of habitat patches bordered by roads are less permeable than roadless edges.

Objectives

We tested whether edge permeability and avoidance are influenced by the presence of paved and dirt roads bordering habitat patches, relatively to roadless edges.

Methods

We translocated 55 montane akodonts (Akodon montensis) from the interior of vegetation remnants to their edges, and tracked fine-scale movements using spool-and-line devices. Edges were bordered by dirt roads (n = 12 mice), paved roads (n = 21) or were not bordered by roads (n = 22). We assessed edge permeability by comparing the number of tracks with crossings, and by comparing the empirical data to simulated correlated random walks. We also assessed edge avoidance by comparing the net direction travelled and net displacement from edge.

Results

No edge crossings were recorded in roaded edges, whereas 36% of tracks in roadless edges crossed the edge at least once. Simulations indicated a significantly lower permeability of roaded edges, while the observed number of crossings in roadless edges was within the expected range. We found no evidence of higher avoidance of roaded edges, as both net direction travelled and displacement were similar across edge types.

Conclusions

Roads decreased edge permeability for the montane akodont. This is likely to increase population isolation among vegetation remnants by reducing the structural connectivity in the already fragmented landscape.

     

Empirical estimation of dispersal resistance surfaces: a case study with red-cockaded woodpeckers

Persistence of wildlife populations depends on the degree to which landscape features facilitate animal movements between isolated habitat patches. Due to limited data availability, the effect of landscape features on animal dispersal is typically estimated using expert opinion. With sufficient data, however, resistance surfaces can be estimated empirically. After modeling suitable prospecting habitat using an extensive dataset from the federally endangered red-cockaded woodpecker (Picoides borealis), we used data from over 800 prospecting events from 34 radio-tagged birds to identify the best relationship between habitat suitability and resistance surfaces. Our results demonstrated that juvenile female P. borealis prospecting for new territories beyond their natal territories preferred to traverse through forests with tall canopy and minimal midstory vegetation. The non-linear relationship between habitat suitability and resistance surfaces was the most biologically relevant transformation, which in turn identified the specific forest composition that promoted and inhibited prospecting and dispersal behavior. These results corresponded with over 60 % of dispersal events from an independent dataset of short-distance dispersal events. This new understanding of P. borealis prospecting behavior will help to identify areas necessary for maintaining habitat connectivity and to implement effective management strategies. Our approach also provides a framework to not only estimate and evaluate resistance surfaces based on species-specific responses to intervening landscape features, but also addresses an often-neglected step, selecting a biologically relevant function to transform habitat suitability model into a resistance surface.     

Mapping hotspots of multiple landscape functions: a case study on farmland afforestation in Scotland

Many conservation and restoration efforts in developed countries are increasingly based on the premise of recognising and stimulating more ‘multi-functionality’ in agricultural landscapes. Public policy making is often a pragmatic process that involves efforts to negotiate trade-offs between the potentially conflicting demands of various stakeholders. Conservationists’ efforts to influence policy making, can therefore benefit from any tool that will help them to identify other socio-economic functions or values that coincide with good ecological conservation options. Various types of socio-economic objectives have in recent years been mapped across landscapes and so there are now important opportunities to explore the spatial heterogeneity of these diverse functions across the wider landscape in search of potential spatial synergies, i.e. ‘multiple win locations’ or multifunctional ‘hotspots’. This paper explores the potential occurrence of such synergies within the agricultural landscape of northeast Scotland and evaluates an existing woodland planting policy using and combining three different policy objectives. Our results show that there are indeed broad areas of the studied landscape where multiple objectives (biodiversity, visual amenity and on-site recreation potential) could be achieved simultaneously (hotspots), and that the case study which we evaluate (the Farm Woodland Premium Scheme) could be much better spatially targeted with regards to each individual objective as well as with regards to these hotspots of multifunctionality.

Behavior as a tool for assessing a managed landscape: a case study of the Karner blue butterfly

In an increasingly human-dominated landscape, effective management of disturbance-maintained ecosystems, such as grasslands and savannas, is critical to the conservation of biodiversity. Yet, the response of individual organisms to landscapes created by disturbances and management is rarely studied. In this study, we examined the endangered Karner blue butterfly, Lycaeides melissa samuelis, in a heterogeneous oak savanna. Our objective was to quantify the butterfly’s habitat use and behavior to assess the effects of prescribed burning. The oak savanna management in Ohio, USA divides each Karner blue site (n = 4) into three units. Each one-third unit is then burned, mowed, or unmanaged in an annual rotation within each site, and the result is a fire return interval of ~3 years. Our surveys measured habitat use, while behavior observations quantified reproduction and foraging for the two annual broods. Our habitat use results showed burned treatments were recolonized quickly, but there was not a clear selection for burned treatments. Foraging rates were similar in all treatments; however, females oviposited significantly less in unmanaged treatments (only 5 of 127 ovipositions). This oviposition preference was likely due to habitat degradation and the availability of recently burned, early successional habitat. Since Karner blues avoided reproduction in units unburned for ≥4 years, these units could be burned to create high quality early successional habitat. These results demonstrate how behavioral decisions can be pivotal forces driving spatial population dynamics. Our case study demonstrates how a fine-scale landscape perspective combined with measurements of behavioral processes can assist with management decision-making.     

Characterizing wild ass pathways using a non-invasive approach: applying least-cost path modelling to guide field surveys and a model selection analysis

Movement of animals is a key process affecting population dynamics. Information on factors that affect pathway use is essential for identifying and protecting pathways, and important for maintaining connectivity among populations. We present an innovative, non-invasive, approach for predicting pathways of reintroduced Asiatic wild ass (Equus hemionus) in Israel, which is based on understanding the effects of landscape factors on pathways use. The approach includes: Predicting pathways, by employing a least cost pathway (LCP) GIS models based on several landscape factors, so as to efficiently direct a field survey and explore the wild ass’s general preferences of pathway types; Collecting empirical data by surveying the dung density of wild ass along each of the predicted pathways and using the data as an index of pathway use; Evaluating the predicted pathways against the empirical data collected, to estimate the general pathway preferences of the wild ass; and Developing and evaluating alternative generalized linear models, according to a priori hypotheses based on empirical data so as to quantify the effect of different landscape factors on pathway use. The analyses were conducted for the entire landscape, and then for two distinct landscape types, open landscape and landscape-barriers (mountain ridges), as subsets of the entire landscape. There were clear differences in the mean number of faeces counts between the LCPs, indicating that the wild ass prefers certain pathway types as a function of landscape features. We further found that the factors affecting E. hemionus pathway usage—vegetation; slopes; canyons; and 4-wheel drive routes—varied largely between the two major landscape types studied, demonstrating the importance of studying space use patterns at different landscape terrains. This information can be applicable to landscape planning measures that aim to enhance protection of the species. This approach provides a framework for studying animal space-use patterns of a variety of species, including elusive species, in a heterogeneous landscape.     

Plant selection method for urban landscapes of semi-arid cities (a case study of Tehran)

Choosing appropriate plants for urban landscapes is vital to avoid potential financial and environmental losses that may occur if all selection parameters are not taken into account. A methodology has been developed to assist landscape architects, planting designers, and urban horticulturists in the plant selection process. Tehran has been picked as a case study due to its arid and semi-arid climate which poses more challenges in front of an expert. After grouping plants, selection parameters have been defined for each plant group. Plant species were comparatively graded for each parameter by a group of eight specialists. Analytical hierarchy process (AHP) technique and hierarchical cluster analysis have been utilized to find the most adaptable plant species for the area according to the main selection parameters of zone tolerance, urban conditions, esthetics, maintenance, growth characteristics, and specific features. Several new plants were ranked high in the final tables suggesting that the urban landscape of Tehran has a great potential to become more attractive, less allergic, and less costly, as well as consuming less water. Before introducing new plants to the urban environment, they should be experimented on in small numbers for several years to confirm that they will not change the ecology of the whole region through invasion or posing a threat to any local plant species.     

Evaluating methods for identifying large mammal road crossing locations: black bears as a case study

Landscape Ecology - Roads have several negative effects on large mammals including restricting movements, isolating populations, and mortality due to vehicle collisions. Where large mammals...     

Using spatial analysis to drive reserve design: a case study of a national wildlife refuge in Indiana and Illinois (USA)

Our refuge design strategy involves a landscape approach formulated to complement existing management efforts and employ restoration in the heavily degraded Kankakee River watershed in northeastern Indiana and northwestern Illinois. The watershed historically contained an approximately 400,000 ha wetland (Grand Marsh), a diverse riverine system, oak savanna, and prairie. Today only fragments of these habitats remain. The U.S. Fish and Wildlife Service developed a preliminary project proposal (PPP) during the summer of 1996 to protect and restore habitat within the watershed by establishing the Grand Kankakee Marsh National Wildlife Refuge. The Indiana and Illinois Gap Analysis projects provided the resources to move beyond the expert workshop approach to a data-driven method for initial reserve design. Using visual analysis of various Gap Analysis data layers, we established Focus Areas that formed the basis for the Environmental Assessment and the Economic Impact Study required under the National Environmental Policy Act (NEPA). We have initiated Phase II of the reserve design analysis using preliminary results of the Indiana Gap Analysis project and C-Plan software in conjunction with the New South Wales National Parks and Wildlife Service.     

Plant-pest interactions in time and space: A Douglas-fir bark beetle outbreak as a case study

A conceptual model of Douglas-fir bark beetle (Dendroctonus pseudotsugae) dynamics and associated host tree mortality across multiple spatial and temporal scales was developed, then used to guide a study of the association between the occurrence of beetle- killed trees and factors that might render trees more susceptible to attack. Long-term records of beetle kill showed that beetle epidemics were associated with windstorms and drought at statewide and local spatial scales. At the landscape scale, beetle kill was associated with (i) portions of the landscape that were potentially drier (southern aspects, lower elevations) and (ii) portions of the landscape that had more mature and old-growth conifer vegetation. The patches of beetle-killed trees were aggregated with respect to other patches at scales of approximately 1 and 4 km. At the scale of the individual tree, there was not a strong relationship between beetle kill and resistance to attack measured by tree growth rate prior to attack. Our results show that landscape-scale phenomena and temporal patterns were more strongly correlated with beetle-kill events than was recent growth history at the scale of individual trees. We suggest that the multi-scale approach we employed is useful for elucidating the relative roles of fine- versus coarse-scale constraints on ecological processes.     

Using animal movement behavior to categorize land cover and predict consequences for connectivity and patch residence times

Context

Landscape-scale population dynamics are driven in part by movement within and dispersal among habitat patches. Predicting these processes requires information about how movement behavior varies among land cover types.

Objectives

We investigated how butterfly movement in a heterogeneous landscape varies within and between habitat and matrix land cover types, and the implications of these differences for within-patch residence times and among-patch connectivity.

Methods

We empirically measured movement behavior in the Baltimore checkerspot butterfly (Euphydryas phaeton) in three land cover classes that broadly constitute habitat and two classes that constitute matrix. We also measured habitat preference at boundaries. We predicted patch residence times and interpatch dispersal using movement parameters estimated separately for each habitat and matrix land cover subclass (5 categories), or for combined habitat and combined matrix land cover classes (2 categories). We evaluated the effects of including edge behavior on all metrics.

Results

Overall, movement was slower within habitat land cover types, and faster in matrix cover types. Butterflies at forest edges were biased to remain in open areas, and connectivity and patch residence times were most affected by behavior at structural edges. Differences in movement between matrix subclasses had a greater effect on predictions about connectivity than differences between habitat subclasses. Differences in movement among habitat subclasses had a greater effect on residence times.

Conclusions

Our findings highlight the importance of careful classification of movement and land cover in heterogeneous landscapes, and reveal how subtle differences in behavioral responses to land cover can affect landscape-scale outcomes.

     

Uncertainty analysis as a tool for refining land dynamics modelling on changing landscapes: a case study in a Spanish Natural Park

In this study we developed a methodology aimed at improving the assessment of inter-annual land cover dynamics from hard classified remotely sensed data in heterogeneous and resilient landscapes. The methodology is implemented for the Spanish Natural Park of Sierra de Ancares, where human interference during the last century has resulted in the destruction and fragmentation of the original land cover. We ran supervised classifications, with a maximum likelihood algorithm (Maxlike), on a temporal series of Landsat images (1991–2005), followed by an uncertainty assessment using fuzzy classifications and confusion indices (CIs). This allowed us to show how much (and where) of the resulting maps contained a substantial amount of error, distinguishing data that might be useful to measure land change from data that are not particularly useful when applying a post-classification comparison methodology. In this way, we can detect true changes not skewed by the effects of uncertainty. Even if patterns of change were always coherent amongst years, they were more realistic after reducing uncertainty, in spite of a substantial decrease in the number of available pixels (i.e. unmasked by the method). We then computed land cover dynamics by means of a model specifically designed to determine the frequency of disturbances (mainly fire events) and the vegetation recovery time during the study period. Model outputs showed correlated landscape patterns at a broad scale and provided useful results to explore land cover change from pattern to process.     

Landscape planning: a working method applied to a case study of soil conservation

A working method for landscape planning is proposed. There are 11 steps in this method. In step one, an issue (or set of related issues) is identified as posing a problem or an opportunity to people and/or the environment. In step two, a goal (or several goals) is established to address the problem. In steps three and four, ecological inventories and analyses are conducted at two scales, first at the regional level (drainage basins are suggested as an appropriate unit) and then at the landscape level (watersheds are recommended). These inventories and analyses consider human ecology as well as bio-physical processes. Step five involves detailed studies, such as suitability analyses, that link inventory and analysis information to the problem(s) and goal(s). In step six, concepts are developed that lead to a landscape (watershed) master plan in step seven. During step eight, the plan is explained through a systematic educational effort to the affected public. In step nine, detailed designs are developed. In step 10 the plan and designs are implemented. Step 11 involves administering and monitoring the plan. The method is explained through an example of soil conservation planning. The case study was undertaken in the Missouri Flat Creek watershed of the Palouse region in the Pacific Northwest (U.S.A.) to help achieve the goals for erosion control established by the federal Food Security Act of 1985 and state clean water legislation.     

Human appropriated net primary productivity as a metric for land use planning: a case study in the US Great Lakes region

Context

Human appropriation of net primary productivity (HANPP) is employed as a measure of human pressures on biodiversity, though largely at global and national scales rather than landscape to regional scales where many conservation decisions take place. Though gaining in familiarity, HANPP is not widely utilized by conservation professionals.

Objectives

This study, encompassing the US side of the Great Lakes basin, examines how regional distributions of HANPP relate to landscape-based biodiversity proxy metrics used by conservation professionals. Our objectives were (1) to quantify the HANPP of managed lands at the county scale; and (2) to assess spatial patterns of HANPP in comparison to landscape diversity and local habitat connectedness to determine if the metric can provide useful information to conservation professionals.

Methods

We aggregated forest and cropland NPP data between 2005 and 2015 and coupled it with previously published potential vegetation maps to quantify the HANPP of each county in the study region. We mapped the outputs at 500 m resolution to analyze spatial relationships between HANPP and landscape metrics of biodiversity potential.

Results

Area-weighted HANPP across our study region averaged 45% of NPP, down to 4.9% in forest-dominated counties. Greater HANPP correlated with reduced landscape diversity (p?<?0.001, r²?=?0.28) and reduced local habitat connectedness (p?<?0.001, r²?=?0.36).

Conclusion

HANPP could be used as an additional tool for conservation professionals during regional-scale land use planning or conservation decision-making, particularly in mixed-use landscapes that both support important biodiversity and have high levels of primary production harvest.

     

Multiple factors shape the interaction of people with urban greenspace: Sweden as a case study

This study identifies and analyses multiple factors that impact people’s interactions with urban greenspace in Sweden. An unrestricted, self-selected online survey was used to collect the data. The survey questions were related to individual characteristics of respondents, including socio-demographic characteristics, self-reported nature connectedness, and self-reported constraints to greenspace usage; perceived characteristics of urban greenspace, including its availability, quality, and accessibility, and benefits and problems; and preferences of respondents regarding types of urban greenspace and activities. Additionally, several spatially explicit variables were included in the analysis. A total of 2806 respondents from 208 (of 290) municipalities completed the survey. Our findings indicate that greenspace users are highly heterogeneous and utilise diverse green spaces along the urban-peri-urban gradient for various benefits. The statistical analyses identified 61 explanatory variables that affect the frequency of interactions with urban greenspace. In addition, we identify key factors that shape critical differences between frequent and infrequent urban users, such as nature connectedness, perceptions of urban greenspace functions, and their perceived accessibility. Our results highlight the complex challenge facing urban planners and managers of green spaces, who have to consider and integrate a vast array of factors influencing the willingness of increasingly diverse urban populations to interact with greenspace.     

Evaluation of an agricultural experiment station as a case study site for the establishment of a multi-use urban forest

In an attempt to contribute towards a more sustainable development for the island of Puerto Rico, this project focuses on the documentation and evaluation of the Tropical Agriculture Research Station (TARS) near the urban center of the city of Mayagüez, Puerto Rico as a case study site to establish a multi-use and research-oriented urban forest. This location has been used since the beginning of the 20th century as a plant introduction and evaluation site, and as an in situ germplasm collection for numerous plant species. The evaluation methods consisted of identifying unique resources within the study area and stressors which could affect the latter. Unique resources were also identified on a Preliminary Resource Inventory Map (PRIM) using GPS technology. Obtained results and observations indicate that the study area represents a major potential asset for the positive economic, social, and educational development of the Mayagüez urban area due to its unique, historic, and complex ecosystems with significant environmental and cultural resources. Of the identified stressors, urban expansion was considered as the most threatening. Hypothetical recommendations providing a base for future development and management efforts in the study area were formulated with the objective of protecting and sustainably using its resources, while promoting environmental and socioeconomic benefits in the region.     

Patterns of abundance and movement in relation to landscape structure: a study of a common scarab (Canthon cyanellus cyanellus) in Southern Mexico

Few relevant data are available to analyze how landscape features affect the abundance and movement patterns of tropical insects. We used mark-release-recapture techniques to study the effects of landscape structure and composition on habitat preferences and movements of Canthon cyanellus cyanellus individuals, within a complex tropical deciduous forest landscape in South Mexico during 2004 and 2005. In total, 2,460 individuals of C. c. cyanellus were captured, including 1,225 females and 1,235 males, out of which 124 individuals (65 females and 59 males) were recaptured once, and 9 individuals (seven females and two males) were recaptured twice. The abundance of individuals was equally high in large forest fragments, small forest fragments and hedgerows, but the abundance in pastures was less than half of the abundance in the other habitat types. To disentangle the movement behaviour of the species from the spatially and temporally varying sampling effort, we applied a Bayesian state-space modelling framework with a diffusion based movement model. Males showed generally faster movement rate than females, and they moved faster within forests and hedgerows than within pastures. Contrary to the assumption of the diffusion model, individuals did not move in a continuous fashion, indicated by the large fraction of individuals that were recaptured in the site of release. However, the posterior predictive data did not deviate substantially from the real data in terms of the mean and maximum movement distances recorded, and in terms of the dependence of movement distance on time between captures. Our results suggest that an important component of the biota in Mexican agro-pasture landscapes can utilize contemporary landscape elements such as hedgerows or small forest fragments in addition to large fragments of remnant habitat. These habitats are still locally common in semi-natural ecosystems and require less intensive conservation management.     

Spatial vegetation patterns as early signs of desertification: a case study of a desert steppe in Inner Mongolia,China

Proper assessment and early detection of land degradation and desertification is extremely important in arid and semi-arid ecosystems. Recent research has proposed to use the characteristics of spatial vegetation patterns, such as parameters derived from power-law modeling of vegetation patches, for detecting the early signs of desertification. However, contradictory results have been reported regarding the suitability of those proposed indicators. We used an experiment with multiple grazing intensities as an analog of a desertification gradient and evaluated the performance of two predictors of desertification: percent plant cover and a transition from a patch-area distribution characterized by a power law to another portrayed by a truncated power law, in a desert steppe in Inner Mongolia, China. We found that spatial metrics, such as the largest patch index and coefficient of variation of mean patch area had negative linear relationships with grazing intensity, suggesting that vegetation patches became more fragmented and homogeneous under higher grazing pressure. Using a binning-based method to analyze our dataset, we found that the patch-area relationship deviated from a power-law to a truncated power-law model with increasing grazing pressure, while the truncated power law was a better fit than the power law for all plots when binning was not used. These results suggest that the selection of methodology is crucial in using power-law models to detect changes in vegetation patterns. Plant cover was significantly correlated with stocking rate and all spatial metrics evaluated; however, the relationship between cover and vegetation spatial pattern still deserves a thorough examination, especially in other types of ecosystems, before using cover as a universal early sign of desertification. Our results highlight a strong connection between the vegetation spatial pattern and the desertification associated with heavy grazing and suggest that future studies should incorporate information about vegetation spatial pattern in monitoring desertification processes.     

Use of fourier transforms to define landscape scales of analysis for disturbances: a case study of thinned and unthinned forest stands

Various disturbances such as disease and management practices causecanopy gaps that change patterns of forest stand structure. This study examinedthe usefulness of digital image analysis using aerial photos, FourierTranforms,and cluster analysis to investigate how different spatial statistics areaffected by spatial scale. The specific aims were to: 1) evaluate how a Fourierfilter could be used to classify canopy gap sizes objectively, 2) determinewhich statistics might be useful for detecting and measuring disturbanceimpacts, and 3) examine the potential for this method to determine spatialdomains in a pair of ponderosa pine (Pinusponderosa) stands in the Black Hills of South Dakota,USA.The eventual goal is to develop an operational method of assessing the impactsof natural disturbances such as disease. Results indicated that several spatialmetrics discriminated between harvested and unharvested stands. We hypothesizethat these metrics will be useful as spatial measures of disease impact if theanalyses are performed on specific size classes of forest gaps.This revised version was published online in May 2005 with corrections to the Cover Date.