Topological and geometric properties of amphibian distribution for large scale conservation

Background/Question/Methods

Biodiversity conservation at large scales is urgently due to increasing habitat loss and fragmentation. Understanding topological and geometric perspective of species distribution pattern may provide useful information for linking conservation studies to larger scales. Some topological and geometric properties of the occurred locations of amphibians in Alabama, including 60 species of 12 families, are analyzed by the metrics including clustering coefficient which measures the strength of a group, relationship between occurred locations and species number, fractal dimension of occurred locations which emphasizes spatial irregularity, and distance of nearest-neighbor.

Results/Conclusions

The results indicate that the clustering coefficients of most amphibian species were lower, but the species with limited occurred locations had higher ones, such as Ranta sylvatica and Limnaoedus ocularis. The general relationship between species number and their occurred locations is that most species had less occurred locations, while limited number of species had more occurred locations. The fractal dimension (FD) of all occurred locations of amphibians was about 1.58, while FD for most species was low. Based on the distribution of the distance of nearest-neighbor, there were four types of relationships: linear, logarithmic, power and polynomial. These topological and geometric properties may indicate some intrinsic features about amphibians in Alabama and provide useful information for regional planning. Properly enhancing the landscape linkages across a large area, such as 300-500 km, may be a good regulatory for conservation practice in this region. Some steps need to be included into the planning of biodiversity conservation in Alabama, such as creating or conserving small habitats across agricultural or urban land and maintaining suitable spatial complexity and the nearest neighbors.