Trend in Bare Ground from Tussock Grassland Surveys, Canterbury, New Zealand

Trend in the proportion of bare ground in some Canterbury tussock grasslands is analysed using records of vegetative cover from Fox Peak, South Opuha River (1963-1985); Porter River (1976-1984); Waimakariri Basin (1962-1978); and central Waimakariri River (1947-1981). The overall proportion of bare ground changed little in all four surveys. The lowest altitude site at Fox Peak and a low altitude plot in Porter River, showed a significant decrease in bare ground. Other plots and transects in Porter River and Fox Peak, and the Waimakariri Basin records showed no overall change. No significant trend was found for any of the central Waimakariri River transects, although some 20 m long segments of some transects show significant trends. The surveys suggest that there has been no overall increase or decrease in bare ground in the last 10-35 years, although vegetation composition has changed in some areas and significant decreases have occurred on some low altitude sites and significant increases on sites with more than 80% bare ground.