Development of a spatialy explicit habitat patch model (C-PAN) and comparative analysis of patch modeling techniques: The crafting of a new tool for conservation planners

Ecological theories including island biogeography, intermediate disturbance, metapopulation and metacommunity all suggest that habitat patches of larger size and those comprised of substantial configurations of interior or core habitat possess the greatest potential for long-term species viability. As a direct means of mitigating edge encroachment and fragmentation's other adverse effects, there is a growing consensus among conservation planners that assembling larger, more cohesive tracts with substantial core area is of ecological value in conservation planning.;This research developed a spatially explicit patch modeling approach designed to incorporate these metrics. This new modeling tool is entitled the Cohesive-Patch Aggregation and Network (C-PAN) model. The model was first tested at a pilot scale (the State of South Carolina) and then up-scaled to evaluate a much larger area (the Northern Appalachian/Acadian Ecoregion). The C-PAN approach is most appropriate for use on species requiring substantial core area and those sensitive to edge characteristics. It is also intended to serve as an alternative approach to heavily parameterized patch modeling methods when species-specific parameterization data are not available.;The C-PAN model was used to generate a unique set of patches in the Northern Appalachian/Acadian Ecoregion. C-PAN was then compared to two ArcGIS (v9.3) based commonly used patch generation tools. The tools, Corridor Designer (v1) and FunConn (v1) were used for this analysis because they represent two highly utilized approaches which are most similar to the C-PAN model in both modeling mechanics and process. C-PAN performed well when compared to the existing patch modeling tools of Corridor Design and FunConn. For all of the spatial and target capture metrics measured, C-PAN ranked first or second among all approaches.;The C-PAN patch network scenario was comprised of the greatest number of patches. This ultimately resulted in the delineation of multiple and potentially functional redundancies in the landscape network. Increasing the number of patches also improved distance metrics within the minimum spanning tree for this scenario. More patches served as intermediate stepping stones which resulted in shorter linkage and edge lengths and smaller average area corridor requirements. The FunConn patch landscape network however connected significantly fewer patches. This resulted in the longest linkage and edge distances and the largest average corridors within the ecoregion. This represents an apparent tradeoff between the number of potentially beneficial redundant connections and total landscape network corridor area. While more connections may contribute to increased landscape connectivity and landscape function, the increased area requirement make it more costly to implement. On the other hand, fewer connections may be less costly from an implementation standpoint, but may also reduce landscape connectivity and ecological function.;The landscape networks were then used to test a simplifying assumption often used in conservation planning: that coarse-scale corridors may provide overlapping or "umbrella" effects for other scenarios. This was accomplished by conducting an analysis of corridor overlap among these three scenarios. This work is among the first corridor gap analyses to be conducted at the ecoregion-scale. The corridor gap analysis indicated that 5% of the corridor area for all 3 scenarios was spatially coincident, 34% was coincident over 2 scenarios, while the majority of corridor area (59%) was non-redundant. As there was so little modeled corridor area in common among scenarios, there is little reason to believe alternate corridors would be functionally equivalent. This indicates that connecting any one set of habitat nodes would not likely serve as a corridor umbrella for all other scenarios.;Of additional interest, the large size and area requirements of ecoregion-scale corridors may prove to be potential mechanisms by which landscape scale gradients and processes can be included within present day networks of protected lands. While this research did not explore this explicitly, ecoregion-scale corridors may prove to be a provocative means by which natural disturbance regimes, environmental gradients, and shifting species ranges may be captured in conservation networks by virtue of their large size. As such, it may be worth considering ecoregion-scale corridors as implementable conservation components that may facilitate planning for persistence in the face of global climate change. (Abstract shortened by UMI.)...