COS 60-8
Conserving extirpated sites: Using habitat quality to manage unoccupied patches for metapopulation persistence

Wednesday, August 13, 2014: 10:30 AM
Regency Blrm B, Hyatt Regency Hotel
Tara M. Cornelisse, Center for Biodiversity and Conservation, American Museum of Natural History, New York, NY

Conservation of metapopulations requires managing extirpated sites, particularly with current threats of increased fragmentation and displacement from global warming. Determining the habitat requirements of threatened species and how they relate to defining characteristics of occupied and unoccupied sites is key to managing suitable habitat in extirpated patches. Due to habitat destruction and degradation, the endangered Ohlone tiger beetle (Cicindela ohlone) is currently found in only five sites of a once more extensive metapopulation in Santa Cruz County, California. To determine the role of habitat quality in classifying sites, I measured vegetation and ground cover as well as plant and soil composition in sites in which C. ohlone are present, extirpated, and absent. I used conditional inference trees to determine what habitat factors significantly classified and predicted the different sites types. I also analyzed habitat characteristics within present sites to determine factors that classified egg-laying habitat. Finally, as isolation has been shown to be an important driver of metapopulation patch extirpation, I tested the spatial autocorrelation of C. ohlone occupancy to determine if unoccupied patches were significantly isolated. 


Habitat characteristics successfully differentiated and classified 90% of extirpated plots, which were not significantly isolated from occupied sites. Extirpated sites were characterized as having no bare ground, low forb, and high percent grass cover. Present sites had at least 10% bare ground cover, high forb cover, low litter cover and depth, and high soil bulk density, characteristics that extirpated sites lacked. These habitat characteristics correctly classified only 61% of present sites; yet, when examining habitat within present sites, characteristics correctly differentiated 88% of egg-laying habitat from non-breeding areas, indicating the heterogeneous nature of C. ohlone habitat and critical importance of certain habitat features for population survival. I illustrate how the defining characteristics can be used to manage habitat in present sites for population expansion as well as in extirpated and absents sites for recolonization or translocation, which is vital for metapopulation persistence.