UNICOR: a species connectivity and corridor network simulator

Landguth, Erin L.; Hand, Brian K.; Glassy, Joseph M.; Cushman, Samuel A.; Sawaya, Michael A.

doi:10.1111/j.1600-0587.2011.07149.x

Cited by 160 publications

(149 citation statements)

References 35 publications

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“…There are numerous methods and software for delineating corridors (Theobald, Norman & Sherburne 2006;Compton et al 2007;Majka, Jenness & Beier 2007;McRae et al 2008;Saura & Torn e 2009;Landguth et al 2012;Br as et al 2013;Carroll 2013;Pelletier et al 2014). One concern with current methods of mapping functional connectivity is that some algorithms require independent, field-collected data, such as species distribution data, occurrence data or movement paths (Cushman, Landguth & Flather 2013;LaPoint et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Landscape connectivity for wildlife: development and validation of multispecies linkage maps

et al. 2014

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Summary1. The ability to identify regions of high functional connectivity for multiple wildlife species is of conservation interest with respect to habitat management and corridor planning. We present a method that does not require independent, field-collected data, is insensitive to the placement of source and destination sites (nodes) for modeling connectivity, and does not require the selection of a focal species. 2. In the first step of our approach, we created a cost surface that represented permeability of the landscape to movement for a suite of species. We randomly selected nodes around the perimeter of the buffered study area and used circuit theory to connect pairs of nodes. When the buffer was removed, the resulting current density map represented, for each grid cell, the probability of use by moving animals. 3. We found that using nodes that were randomly located around the perimeter of the buffered study area was less biased by node placement than randomly selecting nodes within the study area. We also found that a buffer of ≥ 20% of the study area width was sufficient to remove the effects of node placement on current density. We tested our method by creating a map of connectivity in the Algonquin to Adirondack region in eastern North America, and we validated the map with independently collected data. We found that amphibians and reptiles were more likely to cross roads in areas of high current density, and fishers (Pekania [Martes] pennanti) used areas with high current density within their home ranges. 4. Our approach provides an efficient and cost effective method of predicting areas with relatively high landscape connectivity for multiple species..

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Section: Introductionmentioning

confidence: 99%

Landscape connectivity for wildlife: development and validation of multispecies linkage maps

et al. 2014

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“…We applied two different approaches: (A) least cost path modeling, using the UNICOR software (Landguth et al 2012), in which the movement of individuals is assumed to follow the optimal (least costly) pathway between locations and (B) circuit theory, using CIRCUITSCAPE (v3.5.8; Beier 2007, McRae et al 2008), in which multiple available pathways (including suboptimal ones) can be followed by the individuals and contribute to estimated connectivity among locations. These two approaches were used to (1) produce corridors expected to concentrate brown bear movements in the study area (least cost path density and current density map for approaches A and B, respectively; further details on our analyses can be found in Appendix A), and to (2) calculate the accumulated cost of movement between source and destination areas, corresponding to the so called v www.esajournals.org effective distances in least cost path modeling and to effective resistances (or resistance distance) in circuit-based modeling (hereafter both referred to as effective distances).…”

Section: Corridor Identification and Effective Distance Estimationmentioning

confidence: 99%

Estimating effective landscape distances and movement corridors: comparison of habitat and genetic data

et al. 2015

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Abstract. Resistance models provide a key foundation for landscape connectivity analyses and are widely used to delineate wildlife corridors. Currently, there is no general consensus regarding the most effective empirical methods to parameterize resistance models, but habitat data (species' presence data and related habitat suitability models) and genetic data are the most widely used and advocated approaches. However, the practical consequences of applying one or the other approach have not been well studied. To address this knowledge gap, we performed a comparative study on the implications of using habitat suitability versus genetic data for determining effective landscape distances (a proxy inversely related to isolation among patches) based on least-cost and circuit-theoretic approaches, and for identifying potential movement corridors. For our comparison, we used data for the Cantabrian brown bear in Spain, an endangered population for which connectivity has been identified as a major conservation concern. Our results show that for brown bears, habitat models tend to overestimate resistance to movement through non-optimal areas, whereas genetic data yield higher estimates of effective distances within habitat areas. Therefore, our results suggest that (1) dispersal might be generally less constrained by landscape conditions than habitat utilization in home ranges, and that (2) dispersing animals might be more flexible in their movement behavior than residents are in their habitat resource utilization behavior, with records for residents dominating species occurrence data and subsequent habitat models. The assessed approaches provided dissimilar connectivity models with notable differences in patterns of predicted corridors across the study area, mainly due to differences in predicted connections between subpopulations. Our results highlight that the functional differences in habitat vs. genetic data, as well as the assumptions and potential limitations of different analytical approaches that use these data, need to be considered more carefully in connectivity modeling and subsequent corridor delineation.

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“…Expert systems (Skidmore 1989) have been shown to successfully predict wildlife distribution in the absence of direct field observations (Murray et al 2009). The UNIversal CORridor network simulator (UNICOR; Landguth et al 2012) was used to predict four alternative categories of ''daily refuge-to-crop raid corridors'' along: (1) footpaths, (2) dry river beds, (3) stepping stone farms, and (4) ''control corridors''; the latter based on proximity to refuges and following trajectories of low relief. An independent dataset of elephant presence (Msoffe et al 2007) was used to validate the simulated corridors.…”

Section: Introductionmentioning

confidence: 99%

Smallholder Farms as Stepping Stone Corridors for Crop-Raiding Elephant in Northern Tanzania: Integration of Bayesian Expert System and Network Simulator

Pittiglio

Skidmore

Gils

et al. 2013

AMBIO

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Crop-raiding elephants affect local livelihoods, undermining conservation efforts. Yet, crop-raiding patterns are poorly understood, making prediction and protection difficult. We hypothesized that raiding elephants use corridors between daytime refuges and farmland. Elephant counts, crop-raiding records, household surveys, Bayesian expert system, and least-cost path simulation were used to predict four alternative categories of daily corridors: (1) footpaths, (2) dry river beds, (3) stepping stones along scattered small farms, and (4) trajectories of shortest distance to refuges. The corridor alignments were compared in terms of their minimum cumulative resistance to elephant movement and related to crop-raiding zones quantified by a kernel density function. The ''stepping stone'' corridors predicted the crop-raiding patterns. Elephant presence was confirmed along these corridors, demonstrating that small farms located between refuges and contiguous farmland increase habitat connectivity for elephant. Our analysis successfully predicted elephant occurrence in farmland where daytime counts failed to detect nocturnal presence. These results have conservation management implications.

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UNICOR: a species connectivity and corridor network simulator

Cited by 160 publications

References 35 publications

Landscape connectivity for wildlife: development and validation of multispecies linkage maps

Landscape connectivity for wildlife: development and validation of multispecies linkage maps

Estimating effective landscape distances and movement corridors: comparison of habitat and genetic data

Smallholder Farms as Stepping Stone Corridors for Crop-Raiding Elephant in Northern Tanzania: Integration of Bayesian Expert System and Network Simulator

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