Gumland is a scrubby wetland ecosystem that grows in low-nutrient and acidic soils on land that was once covered in kauri (Agathis australis) forest in northern regions of New Zealand. The gumland ecosystem is a type of heath, containing plants, many of them rare, that are adapted to infertile and harsh conditions. Gumlands are found in Northland and the Auckland Region of the North Island. They are known for having kauri gum in the soil. Gumland ecosystems are critically endangered.
Description
Gumland is a scrubby wetland ecosystem that is a type of heathland. They grow on some of the least fertile and most acidic soils, and are typically found on flat or rolling land that was once covered in kauri (Agathis australis) forest. The soils have lower levels of nutrients than soils in similar heathland in South Africa and Australia. Strongly leached soil has formed from weathering of claystones, sand and sandstones. The soil has changed over thousands of years, with the combination of the weathering and the acidic kauri leaf litter creating a distinct soil type known as podzol. This soil type has limited drainage and can remain wet for extended periods. Gumlands are not always recognised as wetlands, as they can be found on hilltops, staying dry all through summer but becoming waterlogged in winter. Gumlands are named for having kauri gum in their soil.
Distribution
Gumlands occur only in Northland and the Auckland Region, in the North Island. The only remaining true gumland in Auckland is at Waikumete Cemetery. The extent of gumlands probably increased after the arrival of Māori and European people, due to loss of forest through increased fire activity, and also removal of soil. The largest remaining area of gumland, on the Ahipara plateau, experiences frequent fires, but mānuka (Leptospermum scoparium) regenerates rapidly.
Gumlands are a critically endangered ecosystem. They once covered 300,000 hectares of land in the 1840s, though most have been used for farmland, so only a few patches remain. There many other threats, including climate change, human use of land, and gum-diggers recovering kauri gum from the soil. Weeds are also an issue for the gumland patches left.
