plant competition

Factors controlling vegetation restoration of depleted short-tussock grasslands are poorly understood. We investigated effects of mouse-ear hawkweed (‘hawkweed’, Pilosella officinarum) cover and environmental stress associated with landform and soil type on the rate and pattern of indigenous vegetation recovery from grazing in the highly-modified 1000-ha Lake Tekapo Scientific Reserve in the north of the Upper Waitaki (‘Mackenzie’) Basin. The reserve has been destocked of sheep and under effective rabbit control since 1992.

It has been suggested that plants can change soil characteristics via their litter to favour their own species. The New Zealand kauri tree (Agathis australis) presents an interesting case for studying such a positive feedback between plant and soil because it has a huge impact upon the soil. We hypothesised that, under mature kauri trees, compared with sites outside the projection of the crown, seedlings of angiosperm trees are relatively rare, while kauri seedlings are relatively common, due to the poor soil conditions and the higher light intensity.