Effect of felled wilding pines on plant growth in high country grasslands

Abstract

Wilding conifers are invading grassland and shrubland ecosystems in the New Zealand high country. The felling of wildings is common practice to control such infestations. This research investigated the effects of felled pines on growth and composition of grassland vegetation at Mt Barker, Canterbury. The vegetation within areas of dead trees, felled in 1998, was compared with open grassland alongside. Adjacent to the dead trees, mean species number/plot was reduced to seven (native 3.7) compared to open grassland (13.4; native 10.9). Mouse-eared hawkweed (Hieracium pilosella) was dominant in the open grassland plots and had very low cover inside the dead-tree plots. Grasses and native shrubs showed enhanced growth in the dead-tree plots. Average plant height was 21.3 cm compared to 5.4 cm in the open grassland plots. It is suggested that novel microsites and additional nutrients from the decaying trees gave a competitive advantage to some plants for a period of time.