Forest fragmentation

The response of stream communities to forest fragmentation

Forest fragmentation has been extensively researched in terrestrial environments however, the response of stream communities to forest fragmentation is relatively poorly understood. The longitudinal and hierarchical connectivity of streams suggest that freshwater communities may respond differently to fragmentation than terrestrial communities. Furthermore, edge effects associated with forest fragments will operate in markedly different ways. Jon Harding and colleagues have been investigating stream communities in forest fragments on Banks Peninsula (South Island, NZ), a region subjected to widespread deforestation during the late 1800s.

Preliminary findings indicate that several species endemic to Banks Peninsula streams have disjunct distributions caused by forest fragmentation (Harding 2003, pdf, 1.2mb), and a minimum fragment size may be required to support populations of endemic species. Current research interests include the effect of fragment size, isolation and location within the catchment on stream faunal diversity and the downstream export of energy and the responses of communities once the stream has exited a forest (Harding et al 2006, pdf, 290kb).

Model of potential “reset effect” of a forest fragment on a stream in an open landscape (Modified from Harding et al. 2006, pdf, 290kb).

People involved in this project

Jon Harding
Jarred Arthur (Completed MSc Student)

Publications

Harding 2003. Historic deforestation and the fate of endemic invertebrate species in streams. New Zealand Journal of Marine and Freshwater Research 37: 333-345 (pdf, 1.2mb).
Harding, Claassen & Evers 2006. Can forest fragments reset physical and water quality conditions in agricultural catchments and act as refugia for stream invertebrates? Hydrobiologia 568: 391-402 (pdf, 290kb).