Habitats of the British amphibians (4): Agricultural lowlands and a general discussion of requirements

Abstract

Ponds on about 80 km 2 of farmland in Sussex were investigated with regard to breeding amphibians. The survey covered five different geological strata and included 60 ponds (out of a total of more than 200) marked on 1:25000 ordnance maps. Eighteen of these ponds were found on inspection not to exist; the remainder were characterised with respect to surface area, depth, pH, ionic score, aquatic vegetation, fish fauna and surrounding terrestrial habitats as well as for amphibian species. 14 pools contained amphibians; Triturus vulgaris was the most widespread (9 ponds) closely followed by T. helveticus (8 ponds). T. cristatus occurred at 5 sites, Rana temporaria at 2 and Bufo bufo not at all. The 2 frog sites were very shallow pools on pasture/woodland interfaces; the ideal newt pond had no fish, was 0·5–1·0 m deep and < 200 m 2 in surface area with 5–50% aquatic vegetation cover and a low ionic score (< 400 parts/10 6). Callitriche-containing ponds were particularly favoured, and with terrestrial habitat there was a requirement for a scrub or woodland component.