CorridorDesign

Glossary of corridor design terms

class
See factor
corridor design (or proposed corridor)
A continuous swath of land expected to be the best route for one focal species to travel from a potential population core in one wildland block to a potential population core in the other wildland block. In some cases, the biologically best corridor consists of 2 or 3 strands. Contrast to linkage design (serves many species, not just one).
corridor dweller
See focal species
cost (or resistance)
a pixel attribute that quantitatively represents the difficulty of moving through the pixel for a particular focal species.
cost-weighted distance
a distance between points that reflects the difficulty of moving between them. In ArcGIS, the Cost Distance function calculates cost-weighted distance as the lowest sum of costs associated with a strand of pixels between the two points. Cost-weighted distance is central to least-cost modeling in CorridorDesigner. When graph theory is applied to connectivity, it usually uses cost-weighted distance instead of Euclidean distance.
factor
a pixel attribute such as land cover, elevation, topographic position, slope, or distance to paved road. In our models each factor is assigned a weight representing that factor’s relative contribution to habitat suitability; weights sum to 100%. Within each factor are several classes, for example the factor Land Cover includes classes such as desert scrub, pinyon-juniper woodland, farms, & urban areas, and the factor Topographic Position includes classes such as ridgetop, canyon bottom, & steep slope. To parameterize models in CorridorDesigner, you will need to define reasonable classes for factors measured on a continuous scale (such as elevation or distance to road).
focal species
a group of species chosen to represent the movement needs of all wildlife species in the linkage planning area. Focal species should include (a) species narrowly dependent on a single habitat type, (b) area-sensitive species, and (c) species most sensitive to barriers. Focal species should also include both passage species (able to travel across the matrix in a few days) and corridor dwellers (requiring multiple generations to move between wildland blocks). For some focal species, GIS analysis might not include a corridor model.
graph theory
the mathematical study of pairwise relations between objects (such as wildland blocks or patches) and providing quantitative measures of pairwise and whole-network relationships. CorridorDesigner does not use graph theory metrics. In corridor conservation, graph theory has been used to describe the effect of losing particular patches or connections between patches, but not to design corridors.
habitat patch
See patch
habitat suitability
The ability of a pixel or polygon to support survival and reproduction of a focal species. Our models calculate suitability of a pixel as the weighted combination of suitability due to each of several factors. We assume that pixel resistance (= cost) is the complement of pixel suitability, in other words, 100 minus suitability.
least-cost modeling
a modeling approach that attempts to identify the area with lowest relative resistance (cost) for the focal species between wildland blocks, where resistance is a weighted combination of resistance due to several factors. CorridorDesigner uses least-cost modeling, as does graph theory and most individual-based movement models. Simulated annealing approaches do not use least-cost modeling.
linkage design
The land that should—if conserved—maintain or restore the ability of wildlife to move between the wildland blocks. The linkage design is produced by joining the proposed corridors for individual focal species, and then modifying this area to delete redundant strands, avoid urban areas, include parcels of conservation interest, and minimize edge effects. Contrast to corridor design (serves one species instead of many).
linkage planning area
Includes the protected wildland blocks and the potential linkage area. If the linkage design in this report is implemented, the biological diversity of the entire linkage planning area will be enhanced
moving window
a set of pixels within a specified radius of a particular pixel.
passage species
See focal species
patch (habitat patch)
a group of contiguous pixels with low enough resistance (high enough habitat suitability) that they could support breeding by a focal species. CorridorDesigner asks you to specify the minimum sizes for (a) population patches: large enough to support a breeding population for about 10 years and (b) breeding patches: large enough to support a single successful breeding event.
permeability
Quantitatively identical to habitat suitability. Permeability and resistance are complements such that permeability + resistance = 100. Thus perfectly permeable landscape has zero resistance.
pixel
The smallest unit of area in a raster GIS map — typically 30x30 m. Each pixel is associated with attributes, such as vegetation class, topographic position, elevation, and distance from paved road.
potential linkage area
The area of private and other lands between the wildland blocks, where current and future urbanization, roads, and other human activities threaten to prevent wildlife movement between the wildland blocks. The linkage design would conserve a fraction of this area.
resistance (or travel cost)
A number reflecting the difficulty with which a species can move through a pixel with particular attributes. In our models resistance (or cost) and suitability (or permeability) are scaled 0 to 100. Our models assume that pixel resistance is the complement of the pixel’s habitat suitability; that is, resistance = 100 minus suitability.
simulated annealing
a procedure (such as MARXAN and PATCH) that attempts to identify a set of polygons that meets a conservation goal at minimum cost. These approaches are efficient ways to design a reserve network, but inefficient at designing corridors between pre-defined wildland blocks.
terminus
the start/end points of a corridor. CorridorDesigner typically uses patches within wildland blocks as terminuses.
weight
see factor
wildland blocks
Large areas of publicly owned or other land expected to remain in a relatively natural condition for at least 50 years. The value of these conservation investments will be eroded if we lose connectivity between them. Wildland blocks may include private lands managed for conservation; in Arizona we usually excluded lands owned by the State Land Department (which has no conservation mandate under current law). Although wildland blocks may contain non-natural elements like barracks or reservoirs, they have a long-term prospect of serving as wildlife habitat. Tribal sovereignty includes the right to develop tribal lands within a wildland block.