A Resistant-Kernel Model of Connectivity for Amphibians that Breed in Vernal Pools
Authors: COMPTON, BRADLEY W.; McGARIGAL, KEVIN; CUSHMAN, SAMUEL A.; GAMBLE, LLOYD R.
Source: Conservation Biology, Volume 21, Number 3, June 2007 , pp. 788-799(12)
Abstract:: Pool-breeding amphibian populations operate at multiple scales, from the individual pool to surrounding upland habitat to clusters of pools. When metapopulation dynamics play a role in long-term viability, conservation efforts limited to the protection of individual pools or even pools with associated upland habitat may be ineffective over the long term if connectivity among pools is not maintained. Connectivity becomes especially important and difficult to assess in regions where suburban sprawl is rapidly increasing land development, road density, and traffic rates. We developed a model of connectivity among vernal pools for the four ambystomatid salamanders that occur in Massachusetts and applied it to the nearly 30,000 potential ephemeral wetlands across the state. The model was based on a modification of the kernel estimator (a density estimator commonly used in home range studies) that takes landscape resistance into account. The model was parameterized with empirical migration distances for spotted salamanders (Ambystoma maculatum), dispersal distances for marbled salamanders (A. opacum), and expert-derived estimates of landscape resistance. The model ranked vernal pools in Massachusetts by local, neighborhood, and regional connectivity and by an integrated measure of connectivity, both statewide and within ecoregions. The most functionally connected pool complexes occurred in southeastern and northeastern Massachusetts, areas with rapidly increasing suburban development. In a sensitivity analysis estimates of pool connectivity were relatively insensitive to uncertainty in parameter estimates, especially at the local and neighborhood scales. Our connectivity model could be used to prioritize conservation efforts for vernal-pool amphibian populations at broader scales than traditional pool-based approaches.
Keywords: Ambystomatidae; Ambystoma opacum; Ambystoma maculatum; amphibian conservation; metapopulation; pond-breeding amphibian; resistant-kernel model; seasonal pond; vernal pool; Ambystomatidae; Ambystoma opacum; Ambystoma maculatum; anfibios que se reproducen en charcos; charcos vernales; conservación de anfibios; metapoblación; modelo de núcleo resistente
Document Type: Research article
Publication date: 2007-06-01