Deforestation

In pre-human times, almost all of New Zealand was covered in forest, with the exception of high mountain areas. Māori settlers began to clear forest, and by the time the first Europeans arrived in New Zealand, up to 40% of the original forest cover had gone.

Rights: Lara Bieleski

Native forest

Native forest showing plant diversity. Forested areas support a huge variety of wildlife, from fungi and lichens, to plants, insects and animals. Deforestation results in loss of habitat, extinction of wildlife and loss of biodiversity.

Early European settlers used timber for housing and fuel. They also felled large areas of kauri forest to export the high quality timber. Many of the trees they logged were over a thousand years old! Forests were also burnt off to provide land for farming. Only 25% of New Zealand is now covered in native forest.

Native forests are of great importance to New Zealand as a habitat for unique birds and plants and as part of our cultural identity. The forests are also a resource for recreation and as a tourist attraction.

Biodiversity

Forested areas support a huge variety of wildlife, from fungi and lichens, to plants, insects and animals. Deforestation results in loss of habitat, as well as the possibility of extinction of a huge variety of wildlife and loss of biodiversity. Organisations such as the Ministry of Agriculture and Forestry and the Department of Conservation are involved in management of New Zealand’s native forest to protect it from logging, damage through fires or loss of biodiversity caused by introduced mammals such as rats, possums and deer.

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Habitat loss

Deforestation results in the loss of habitat for many species. A large proportion of New Zealand’s native forest has been cleared for farming and settlement.

Water

Forested areas slow the flow of water, allowing it to soak into the soil and into underground water channels. When trees are removed, water is unable to soak into the soil and, instead, runs off the surface at a faster rate. This can cause localised flash floods and erosion, particularly in mountainous regions. Pollutants are also easily washed into waterways.

Rights: Lara Bieleski

Beech trees

Beech trees in front of a waterfall. Removing trees causes water to run-off the surface at a faster rate. This increases the risk of erosion, landslides and flooding, particularly in regions with steep land, such as on mountains and hills.

Soil erosion

Tree roots form an underground network that stabilises the soil, so deforestation often leads to increased soil erosion. Soil and nutrients are washed off the land and into waterways, changing the quality of the water and affecting wildlife. Eroded land that has lost topsoil can quickly become barren wasteland, as it is not as productive for crops. This land may be abandoned while further areas are deforested.

The type of tree, the place it is planted in a catchment and the way it is managed all have consequences downstream. Whether a forest is standing or harvested can determine the extent of erosion, sedimentation and flood impact in an extreme event.

Climate change

Deforestation threatens to contribute to climate change by reducing the Earth’s ability to control the level of the major greenhouse gas CO₂ in the atmosphere. Plants absorb CO₂ during photosynthesis, and large forest areas can absorb vast amounts. Without forests, the CO₂ is not absorbed and, therefore, goes straight into the atmosphere.