Holly Thoms of Balclutha School asks :-
How many different types of native tree there are in New Zealand?
David Norton, of the School of Forestry at the University of Canterbury, responded.
Before I can answer, I need to define what a tree is. A tree is usually regarded as a woody plant with a distinct trunk that carries its branches above the ground (e.g., rimu or red beech). The other kinds of woody plants are shrubs, which lack distinct trunks, branching from ground level (e.g., Hebe), and climbers with vine like stems (e.g., Clematis).
Sometimes the distinction between trees and shrubs can be difficult, as some shrubs can form short trunks, but there are some 200 different species of tree native to New Zealand. In contrast there are about 300 species of native shrub and some 40 species of native vine. Trees comprise about 10 per cent of all New Zealand's native plants. There are of course many more introduced trees that have been brought to New Zealand over the last few hundred years by human settlers.
The 200 native tree species are not evenly spread across the country, with many more in the northern North Island than in the southern South Island. For example, trees like kauri and pohutukawa are confined to the northern half of the North Island, tawa just makes it as far south as the top of the South Island, while rimu occurs right to the southern end of Stewart Island. One tree, southern rata, extends as far south as the Auckland Islands in the subantartic.