Acid water anuran pond communities along a regional forest to agro-urban ecotone

We related the distributions of adult and larval anurans to 14 environmental variables in 14 acid water ponds: located within drainage areas that displayed a range of agricultural and developed land use cover in the New Jersey Pinelands (Pine Barrens). Species were classified as those restricted to the Pinelands (Pine Barrens species: Hyla andersonii and Rana virgatipes), those with a wide-ranging distribution in southern New Jersey (wide-ranging species: Pseudacris crucifer crucifer, Bufo fowleri, Rana sphenocephala utricularius, and Rana clamitans melanota), and those normally unable to enter the Pinelands except in habitats disturbed by human activities (border-entrant species: Hyla versicolor Pseudacris kalmi, Acris crepitans crepitans, and Rana sylvatica). The frequency of occurrence of Pine Barrens and wide ranging species was greater than that of any border-entrant species. Detrended correspondence analysis revealed an adult community gradient associated with geographic position where border-entrant species were heard only at ponds located along the transition between forested and disturbed landscapes. Principal component analysis revealed a primary environmental gradient of increasing pH and emergent herbaceous vegetation cover and decreasing specific conductance and floating vegetation cover and contrasted natural and artificial (borrow pits) pond types. Floating vegetation cover and specific conductance were lower and pH was higher in artificial versus natural ponds. Larval recruitment occurred for all species except the four border entrants and B. fowleri. Larval species richness was directly related to emergent herbaceous vegetation cover and inversely related to specific conductance. Our results suggest that landscape patterns influence the distribution of adult anurans,whereas pond chemistry may limit recruitment.