Effect of artificial defoliation of mid-ribbed snow tussock, Chionochloa pallens, in the Murchison Mountains, Fiordland, New Zealand

Abstract

Biomass, tillering, and plant chemistry were measured in tussocks of Chionochloa pallens in low-alpine snow tussock grassland in Fiordland in April 1986, eight years after severe clipping in spring, 1977. Clipping increased tiller density, but depressed tiller size and total tussock biomass. Defoliated tussocks responded by decreasing the proportion of total biomass and mineral nutrients allocated to roots, and losing a greater percentage of these resources in leaf senescence. Total non-structural carbohydrate allocation, primarily sucrose and starch, is also significantly reduced in the stems of clipped tussocks. The many severe effects of a single defoliation on Chionochloa pallens tussocks and their slow rate of recovery suggests that it will be two decades, even in the absence of grazing, before they recover fully.

Keywords:

• tussock grassland
• Chionochloa pattens
• grazing
• biomass
• nutrients
• carbohydrates
• Fiordland
• New Zealand