A FUNCTIONAL-ANALYSIS OF NEW-ZEALAND ALPINE VEGETATION - VARIATION INCANOPY ROUGHNESS AND FUNCTIONAL DIVERSITY IN RESPONSE TO AN EXPERIMENTAL WIND BARRIER

1. There is an increasing interest in describing species assemblages i n terms of function or texture, as an alternative to floristics. Howev er, the use of objective criteria for evaluating plant function remain s uncommon. 2. A procedure for determining-plant fractal dimensions wa s applied to the measurement of canopy roughness of alpine plants, as a major functional character in high-alpine cushionfield vegetation in southern New Zealand. 3. The study was carried out within a 50 x 30 m area located around an experimental snow fence. The snow fence was er ected on an originally uniform site 32 years prior to this study. Sinc e its construction it has caused visible changes in snow lie and in th e composition of vegetation on its leeward side, apparently because of its ameliorating effect on microenvironmental parameters. 4. Floristi c patterns across the study area, revealed by a DCA ordination of spec ies frequency data, showed a strong association with snow depth, corre sponding to the sheltering effect of the snow fence. 5. Vegetation can opy roughness increased along a gradient of increasing snow depth, con sistent with the expectation that plants growing in the most exposed a lpine environments would possess smooth canopies that promote laminar air flow over their surface and thus enhance plant/air temperature dif ferentials. 6. Functional diversity in terms of canopy roughness simil arly increased with increasing snow depth, consistent with expectation s of community structure theory. Species richness and Shannon-Wiener s pecies diversity showed similar relations. 7. It is concluded that pla nt canopy roughness, measured by means of fractal dimensions of canopy profiles, has value for predicting the physiognomy of alpine vegetati on from the microenvironment. It is also practical to measure. It shou ld be considered for future studies examining vegetation texture in th e alpine zone.