High altitude ecology: Some ecological aspects of revegetation of eroded kaikouran soil at Black Birch Range, Marlborough
- Grasslands Division, D.S.I.R., Lincoln
In their report on high altitude tall tussock grasslands, the Tussock Grassland Research Committee (1954) drew attention to the scarcity of exotic plants in the high altitude zone after depletion of the snow tussock. In this zone, soil exposed among tussocks is subject to frost lift and wind erosion. Subsoil and eventually parent material are exposed. In some localities, shorter native grasses such as Festuca novae-zelandiae. F. matthewsii, Poa colensoi, Notodanthonia species and Chionochloa australis may cover the exposed soil effectively, but depletion of the grasses results ultimately in extreme erosion. Such a situation exists in the Notodanthonia setifolia-Celmisia spectabilis grasslands on Black Birch Range, Marlborough.
Two sets of experiments to evaluate the ability of several grasses to grow and survive and to withstand frost heaving in this environment were laid down in the spring of 1962 near the temporary Black Birch Observatory at 4,450 ft. The site was an area previously prepared for an airstrip; the hummocks of Notodanthonia and Celmisia had been graded off and the subsoil was exposed. One set of experiments dealt with the influence of mulches and fertilisers on the establishment of sown grasses and clovers (O'Connor, Macarthur and Archer, unpublished); the other is discussed here and deals with the influence of fertilisers on the growth and survival of space-planted grasses and oversown white clover. Some results of the mulching experiment of O'Connor et al. are discussed and conclusions are drawn about the grasses useful for two phases of revegetation—establishment on bare subsoil and survival following establishment. From the two sets of experiments, The importance of climate and soil fertility to revegetation is assessed and the probable plant succession following experimental revegetation is indicated.