Volcanic activity (including lava flows, debris flows and tephra eruptions) is a regular feature of many landscapes of the North Island of New Zealand. We have been using a combination of chronosequence and direct monitoring methodologies and some limited experimental manipulation to research the pattern and process of vegetation change following recent eruptions dating from 5 to 450 years ago. The volcanoes studied over the last 30 years or more are Tarawera, Whakaari (White Island), Rangitoto Island, Ruapehu, Tongariro, Ngauruhoe, and Taranaki, which encompass the full range of coastal to alpine bioclimatic zones.
Our results reveal vegetation pattern and process reflect the style, frequency, intensity and scale of the volcanic disturbance, and biogeographic setting. At one extreme are deterministic direct successions characterised by low to medium species richness and strong facilitation and aggregation mechanisms. At the other are probabilistic multiple pathway successions, characterised by medium to high species richness, and tolerance and inhibition as well as facilitation mechanisms. Forest successions are dominated by Metrosideros and Weinmannia, which are mass seeders and can resprout from epicormic buds. Establishment of nitrogen-fixing Coriaria and infrequent climatic events such as unseasonable frost can significantly alter successional trajectories. We recommend long-term (several human generations) experimental and observational studies using both direct monitoring of permanent plots, as well as careful use of chronosequences, for fuller understanding of vegetation pattern and change on recent volcanic landscapes.