short tussock grassland

In a Festuca novae-zelandiae short tussock grassland in South Island, New Zealand, we tested the propositions (1) that present regional trends in vascular plant species-richness in tussock grasslands are independent of current pastoral management, and (2) that grazing retards the invasion and dominance of nonnative species, particularly where soil resources are not limiting. Sheep and rabbit-grazed, ungrazed, ungrazed+fertilised and ungrazed+irrigated treatments were applied in a replicated experiment that was sampled annually from 1988 to 2000.

The effect of protection from sheep grazing on indigenous plant species in relatively mesic, strongly modified Poa cita grassland, was examined using paired grazed and ungrazed sites. Ungrazed sites, fenced at times ranging from four to more than 24 years ago, had fewer species, lower indigenous cover and lower tussock density than adjacent grazed sites. The dominance of adventive species, particularly cocksfoot (Dactylis glomerata), in ungrazed sites appeared to be important to these differences.