![Sample our Environment & Agriculture journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5934/TOC-Subject-Sample-2021-Environment-Agriculture.jpg"})
Abstract
Regeneration of Chionochloa rigida ssp. rigida (Poaceae) was investigated in two adjacent unburnt sites subjected to different levels of grazing by merino sheep over an 8 year period. The spatial pattern of establishment of immature plants within a 3 m radius of 100 isolated mature tussocks (basal diameter >20 cm) was recorded. Basal diameter, height, canopy width, slope, and aspect of the putative parents were noted, was was the size and position of the immature plants (basal diameter <10 cm). At the lower grazing intensity the number of immature plants increased with tussock size. Small tussocks had disproportionately few immature plants. The regeneration shadow was highly skewed, 72% of all immature plants occurring downhill and downwind from the tussock. Highest densities of recruits established between 0.5 m and 1.0 m from tussock centres. Few immature plants established within one diameter of the base of mature plants. Grazing affected regeneration by: (a) reducing overall recruitment (0.90 versus 4.0 immature plants per tussock); (b) reducing the proportion of seedlings in the smallest size class (20.0% versus 41.4% of seedlings with basal diameter <2 cm); (c) reducing mean seedling height (15.3 cm versus 23.0 cm); and (d) reducing the proportion of more distant immature plants. Regeneration was successful in the absence of fire and at low grazing intensity, probably <0.2 stock units ha-1 yr-l. However, recruitment was low under moderate grazing and uphill and upwind of mature tussocks. These factors need to be considered in the rehabilitation of narrow-leaved snow tussock grasslands in Central Otago.
