CHIONOCHLOA-RIGIDA TUSSOCKS 13 YEARS AFTER SPRING AND AUTUMN FIRE, FLAGSTAFF, NEW-ZEALAND

The residual effects of fire on snow tussock (Chionochloa rigida (Raoul) Zotov) were examined in five areas of tussock grassland at between 500 m and 650 m altitude on Flagstaff, Dunedin. Three sites at different altitudes had been burnt in the spring of 1976, one the previous autumn, and one had not been burnt for at least 25 years. The spring-burnt sites generally had lower canopy cover, tiller density and above-ground biomass than the unburnt site. The two upper spring-burnt sites had significantly lower tiller weight and total leaf length than the other three sites, however the ratio of green to the total leaf length was highest in the uppermost spring-burnt site. The autumn-burnt site differed significantly from the unburnt only in having a greater sheath:total leaf length. The previous belief that spring fires are less damaging to C. rigida tussocks than autumn fires requires further investigation. It is suggested that future studies of the response of C. rigida to fire should include detailed measurements of both tiller and tussock characteristics.