The available literature on ragwort is reviewed. The ecological behaviour of ragwort can be explained by its tendency to act as a colonising plant, which is encouraged by pasture disturbance. Ragwort-infested pasture and closed pasture alternate with each other, and this is influenced by a number of environmental and management factors.
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.