The ecology of tussock grasslands: The plants of tussock grassland
One fifth of New Zealand carries tussock or bunch grass vegetation related to the socalled steppes of the world (1). Tall-tussock grassland has long been distinguished from low-tussock grassland, but further subdivision awaits basic field work. Failing a classification of vegetation types a plant capability survey reviews the restricted range of growth forms present.
Indigenous plants of the primitive grassland are predominantly long-lived, evergreen, mostly spot-bound, poor in seeding and/or seedlings, and with restricted regeneration from either above-ground buds or subterranean perennating organs. Many, like the tussock grasses, consist of loose-knit potentially independent parts that theoretically need never reach senility; it is not at all unusual for a tussock to live 20 years or more. Growth is slow. Fescues in the Waimakariri doubling their number of leaves in three years (2) contrast strongly with ryegrass in which "vigorous tillers can increase in numbers by 70-100 % per week, given adequate light" (3). Size is no guide to age starved tussocks have remained 2in. high with 6-8 leaves for ten years. Such longlived plants influence the underlying soil, affecting temperature and frost action (4) and also water relations.