Effects of grazing on indigenous shrubs in tussock grassland at cass, canterbury, new zealand

Abstract

When enclosures were contrasted with comparable control areas, the effects of grazing over a 17-year period on survival, establishment, and growth were determined for six montane shrub species—Discaria toumatou, Cassinia fulvida, Coprosma parviflora, Coprosma propinqua, Corokia cotoneaster, and Hymenanthera alpina. One exclosure was in open grassland whereas a second encompassed the grassland-beech forest boundary. The shrub populations in the exclosures generally showed greater height growth and lower recruitment rates, but no difference in survival rates, when compared with populations in control areas. These trends do not apply to every species and site. Cassinia fulvida1 in particular showed a dramatic decline in population size that is not related to grazing. For most species, high survival rates, low height growth rates, and constant recruitment contribute to the relative stability of shrub populations. © 1978 Taylor & Francis Group, LLC.