Report: TR 2009/22

Author: R Storey, S Parkyn, B Smith, G Croker, P Franklin, NIWA

Abstract

Headwater streams are the smallest stream channels in a stream network. They are often referred to as “zero-order”, rather than first-order, streams because they typically do not appear on 1:50 000 topographic maps. Zero-order streams account for a high proportion of the total channel length in a stream network, and represent the closest association between the terrestrial and aquatic environments in that network. Studies in New Zealand and overseas have shown that zero-order streams often have unique habitat conditions supporting a distinctive aquatic invertebrate community, and the ecological functions they perform may have a strong influence on the health of the wider stream network. Thus, the first aim of the present study was to determine some of the biological values and ecological functions of zero-order streams compared to those of larger first-order streams, and to quantify the effects of land use on those values and functions. Because they are small, numerous and easy to pipe or infill, zero-order streams are particularly vulnerable to the effects of development. Therefore the second aim of our study was to design a decision support framework for quantifying compensation if land development requires the loss of a zero-order stream by piping or degradation by a change in land use.

Effects of Development on Zero-order Streams in the Waikato Region [PDF, 705 KB]