The alpine and upper montane grasslands of the Wairau River catchment, Marlborough

Abstract

The alpine and upper montane grasslands of the Wairau River catchment are composed mainly of five major and four intermediate plant associations, characterised respectively by the dominance of Cbionocbloa australis, C. rigida, C. flavescens, Notodanthonia setifolia, and Festuca mattbewsii, and as intermediate associations by C australis/C. rigida, C. rigida/C. flavescens, N. setifolia/F. matthewsii, and N. setifolia/Celmisia spectabilis. Of these, the first three major and the first two intermediate were probably the main associations present in the area before disturbance of the vegetation by fire and grazing animals. The remainder appear to be culturally induced associations and it is suggested that they owe their origin, not only to extensive burning and grazing in European times, but also to widespread fires in more ancient times. Notodanthonia setifolia is now the most important single species. It is dominant over wide areas and is an important constituent of many of the other associations present. Habitat factors for the main associations are given in tabular form and specific frequency data are presented illustrating the botanical composition of the swards modified to differing extents by burning and grazing. All swards have been modified; the severe modification of most of them has led to spectacular acceleration of erosion. Relief from grazing (by deer, chamois, goats, and hares mainly, but also locally by sheep and cattle) would help in arresting downwards trends particularly where sward modification is not far advanced, but in many areas of severe modification relief from grazing pressure alone, is unlikely to induce recovery.