New Zealand Journal of Botany abstracts

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Changes in the tussock grasslands in the central Waimakariri River basin, Canterbury, New Zealand, 1947-1981

D. SCOTT

Grasslands Division, DSIR
Private Bag, Christchurch
New Zealand

R. D. DICK*

North Canterbury Catchment Board
Private Bag, Christchurch
New Zealand

G. G. HUNTER

Water and Soil Directorate
Ministry of Works and Development
Private Bag, Christchurch
New Zealand

Present address: 22 Tudor Avenue, Christchurch Abstract Seven mid-altitude grazed tussock grassland transects in the central Waimakariri River basin were repeatedly surveyed between 1947 and 1981. Proportions of living vegetation, dead material, and bare ground were obtained using the point-intercept method, annually from 1947 to 1963 and in 1980 and 1981. Plant species were recorded in 1956,1959,1962, and 1980. The vegetative cover was discontinuous, covering between 20% and 80% of each transect. For combined transects the proportion of living vegetation declined from 1947 to 1953 at a rate of 2.29% yr1. Between 1954 and 1981 the vegetation cover increased at a rate of 0.56% yr1. Over the full period there was no overall significant change in the total extent of living vegetation cover. However, the extent of living vegetation increased on well vegetated sites and declined on poorly vegetated sites. The extent of living vegetation also increased in years with wetter springs, on transects at the lowest altitudes, and on sites dominated by Chionochloa macra, Elymus rectisetus, Discaria toumatou, and Agrostis capillaris. Thirteen species comprise the majority of the living vegetation. Festuca novae-zelandiae decreased consistently on most transects and Pilosella spp. and Leptospermum scoparium increased on some. Other species showed smaller and less consistent changes. Many species increased where they were already major elements and decreased where they were minor. If climate and management conditions of the recent past continue to prevail, the extent of living vegetation is predicted to continue to fluctuate within the ranges recorded over the survey period. Vegetation types dominated by Festuca novae- zelandiae and Celmisia spectabilis are expected to decrease and those dominated by Discaria toumatou, Chionochloa macra, Elymus rectisetus, and Agrostis capillaris are expected to increase.

Keywords high country; tussock grassland; pastoral land; ground cover; Waimakariri River; vegetation analysis; time trends; point intercept

Received 20 March 1987; accepted 25 September 1987
New Zealand Journal of Botany, 1988, Vol. 26: 197-222
0028-825X/88/2602-0197$2.50/0 © Crown copyright 1988

PDF file of entire paper: medium quality (3581K); (scanned from paper original: notes about this process)

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