Studies on the management of snow-tussock grassland

Abstract

Contemporaneous with studies on the effect of burning on snow-tussock (Chionochloa rigida (Raoul) Zotov) observations were made on the effect of fire and fertiliser on resident inter-tussock vegetation and on the establishment and growth of oversown pasture species.

Burning in spring resulted in considerable exposure of bare ground but by the following winter this effect was nullified by effects of applied fertiliser on oversown clover. Fertiliser application had a much larger effect than burning had on the survival, vigour, and yield of clovers. Burning eventually resulted in superior yield of white clover (Trifolium repens L.). Red clover (Trifolium pratense L.) was more prominent than white clover on unburnt plots.

Burning resulted in reduced inter-tussock yield of herbage in the season of the fire. Burnt plots yielded less inter-tussock grass than unburnt plots in the subsequent season. The yield of fescue tussock (Festuca novae-zelandiae (Hack.) Cockayne) in particular was larger on burnt plots in the final year of observations. The principal adventive grasses of the trial area, Yorkshire fog (Holcus lanatus L.) and sweet vernal (Anthoxanthum odoratum L.), responded to applied phosphate, the latter especially on burnt plots. Some trends attributable to burning were detected in minor components of vegetation harvested from intertussock areas. Within the snow-tussocks themselves (the intra-tussock areas) there was a marked increase in alsike clover (Trifolium hybridum L.), white clover, and sweet vernal on fertilised burnt plots.

Measurement of incident light at 3 in. above ground level in the winter following burning showed much higher values on burnt plots than on unburnt plots. Variation within unburnt plots was related to height of snow-tussocks.

The results are discussed in terms of physical and chemical conditions resulting from treatments. Conclusions are drawn concerning the improvement and management of such grasslands.