Impact of post-European stream change on frog habitat: southeastern Australia
Stream geomorphology and fluvial processes in Australia have generallybeen modified substantially since European settlement. In the case of theSouthern Tablelands of New South Wales, in southeastern Australia, detailednotes of early explorers and settlers and early survey maps have providedinsight into the nature of these changes. Early explorers described most streamsin this area as 'chains-of-ponds'. These are ponds connected byshort lengths of channel or divided by grassy intervals. Many of these systemswere converted to incised channels after Europeans arrived. An examination ofthe life history characteristics of frogs and their physiological limitationsprovides insight into how these changes are likely to have affected froghabitat. Chains-of-ponds provided permanent breeding ponds for frog species withextended larval stages. The environment surrounding these ponds floodedregularly, providing breeding habitat for species that can exploit ephemeralwaterbodies. Flood waters and saturated soil also created moist, well-vegetatedenvironments for adult frogs during the non-breeding season. Human impacts andlandscape modification led to channel incision of chain-of-pond systems andresulted in many physical changes in pond characteristics, includingavailability, permanency, structural complexity and flow dynamics. Theimplications of these changes are discussed in this paper. Hypotheses aredeveloped on frog species susceptibility to landscape change associated withchannel incision of chain-of-pond systems.