Earthquake Impacts on Montane Forests

Client: Robert Allen, Independent Researcher

Earthquakes can trigger landslides that damage or kill trees, but their long-term effects on forests are rarely studied, since earthquakes are unpredictable and long-term data is hard to come by. This project looked at a long-term monitoring network in New Zealand's Southern Alps, near Arthur's Pass, following the magnitude 6.7 earthquake there in 1994.

Using that monitoring network, we analysed survival and growth data from over 8,000 mountain beech trees (Nothofagus cliffortioides) before and after the earthquake, looking at how distance from the epicentre, tree size, and soil conditions affected outcomes over time.

Outcome: Tree survival was lower closer to the epicentre. Surprisingly, larger trees fared relatively well. Growth effects faded within a few years, suggesting mountain beech forests are more resilient to earthquake disturbance than expected.

Method: A custom Bayesian model, developed to estimate long-term survival and growth.