Gumlands are 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 gumlands ecosystem is a type of heath, containing plants, many of which are rare, that are adapted to infertile and harsh conditions. Gumlands are found in the Auckland and Northland regions of the North Island. They are known for having kauri gum in the soil. Gumland ecosystems are critically endangered.
Description Gumlands are 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 the 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 during winter. Gumlands are named for having kauri gum in their soil.
Distribution
Gumlands had a restricted distribution in the North Island, specifically in the Auckland Region and Northland, though the only site in Auckland that hosts true gumland is Waikumete Cemetery. The extent of the gumlands had extended prior the arrival of the Māori and the Europeans, primarily due to increased fire activity, as well as wildfires and soil removal. The largest area of gumland remaining is on Ahipara plateau and it is frequently being burnt.
Biodiversity Flora 47% of the vascular flora of the gumlands are endemic, most of them are also native to Australia. The soil also gives a strong diversity for orchids, including undescribed species of Prasophyllum, and many undescribed species of Thelymitra. The most dominant species is the mānuka (Leptospermum scoparium), and the kūmarahou. other dominant scrubby plants include gumland grass tree, bog schoenus, tangle fern, tall mingimingi and Epacris pauciflora. There are threatened species also present in this ecosystem including king fern, mauve sun orchid, and the slender sun orchid.
Fauna Fauna thriving in gumlands include, the black mudfish, an endemic northland mudfish, and the New Zealand fernbird. The ecosystem includes threatened species such as the North Island brown kiwi and northland green gecko. Over 160 species of lepidoptera have been found in the found on gumlands, with several undescribed taxa that have not been found anywhere else.
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