To determine the susceptibility of different forest types to lianes, and to investigate which ecological factors are limiting for lianes, a field survey covering 28 naturally forested sites in Golden Bay (Northwest Nelson) and on Banks Peninsula (Canterbury) was carried out. Results from Detrended Canonical Correspondence Analysis of liane species abundance data in relation to tree and shrub species abundance data and abiotic site variables, showed that the liane community composition was highly correlated with the composition of the tree and shrub community.
The rate of spread of mouse-ear hawkweed (Hieracium pilosella) patches, the effect of hawkweed on soil properties, and the nutrient content of hawkweed biomass was investigated on grazed unfertilised land on Glencairn Station (altitude 440 m, mean annual rainfall 500-600 mm) in the Mackenzie basin, southern South Island, New Zealand. Pallic soils (Typic Ustochrepts) under hawkweed patches and under surrounding herbfield were analysed for exchangeable cations, organic C and total N. Total nutrients in hawkweed and herbfield biomass were measured.
Changes in soil chemistry in relation to hawkweed (Hieracium pilosella) presence were determined at a site receiving less than 600 mm rainfall where hawkweed was colonising Pallic Soils (yellow-grey earths). pH was significantly lower (by 0.5 units) and organic carbon values were significantly higher (0.7% absolute, 40% relative) within hawkweed patches than in adjacent soil, but there was no significant difference in total nitrogen.
Agathis australis (A. australis, New Zealand kauri, Araucariaceae) exerts a substantial influence on soil properties and nutrient cycling, and mature specimens form an acidic organic soil layer beneath them that can be up to 2 m deep. We investigated whether phytotoxic compounds occurred in A. australis leaf litter and organic soil, and whether allelopathy may explain the distinctiveness of plant communities surrounding A. australis.