New Zealand forest giant prevents landslides

The colossal kauri trees prevent landslides on landslide-prone slopes. This is the conclusion of Dutch-funded researcher Lieven Claessens, who developed a model for predicting landslides in the Waitakere Ranges Regional Park in New Zealand.

Claessens has discovered that the kauri trees in New Zealand prevent landslides. When these enormous conifers reached a certain age, they stabilise areas prone to landslides. This maximises the benefit the trees gain by living far longer than other tree species.

At present the slopes are drained and large concrete structures are placed to prevent the landslides and the associated mud flows. According to Claessens planting kauri trees is a natural and in the longer-term possibly better solution for this problem.

During his doctoral research, the Belgian researcher developed a dynamic landscape model to simulate the distribution of soil due to landslides. For this he studied the landscape, soil and vegetation dynamics in the Waitakere Ranges Regional Park in New Zealand. The model can be used to predict the locations where landslides will occur and researchers can also use it to calculate how rainfall affects the soil.

Waitakere Ranges

Waitakere Ranges Regional Park is situated on the North Island of New Zealand. About 1000 years ago this entire island was covered with kauri trees, which can reach a height of 50 metres and grow in the most inhospitable places. The largest kauri tree in New Zeeland is the Tane Mahuta (’king of the forest’). This tree has reached the honourable age of 1500 years, is more than 51 metres high and has a girth of 13.7 metres.

Some of the remaining kauri forests of the island are still inhabited by the original islanders, the Maori’s. They use the trees to build canoes and houses. From the mid-19th century onwards, many kauri trees were chopped down by Europeans for the timber trade. This led to the disappearance of most of these colossal conifers. Hopefully the positive effect of these forest giants on preventing landslides will contribute to their conservation.