A review of vegetation succession following recent (450 years) volcanic disturbance in North Island, New Zealand
In the last 450 years at least 20,000 ha of indigenous vegetation in the North Island has been damaged or destroyed by volcanic disturbance, initiating primary and secondary successions. These are reviewed and considered in relation to some recently proposed models of succession. Most of the variation in succession relates to the scale and intensity of disturbance, and the type and heterogeneity of the substrate emplaced. Where disturbance has been most extensive and severe, elements of slow classical successions, from lichens and mosses to flowering plants, and facilitation by nitrogen-fixers such as Coriaria, are evident. In contrast, minor disturbance results in vegetative regrowth or regeneration of surviving species. Heterogeneity of substrate enables many taxonomic groups of plants to establish more or less concurrently. Intermediate disturbance successions are not easily categorised and may contain elements of several succession models. The recently advanced resource-ratio hypothesis of succession can be used to explain the general pattern of volcanic successions outlined.