Long despised as scrub weeds by farmers, native shrubs are slowly gaining acceptance as a valuable part of the landscape. Shrublands harbour a rich mix of native plants, animals and fungi. These vary around the country, and are mostly not well documented.
Invertebrates and fungi
The rich invertebrate life of native shrublands is slowly being revealed. In a small grazed reserve in Central Otago, 280 different species (spiders, insects, crustaceans, millipedes, snails and worms) were found on and under 30 plants of Olearia bullata, a shrub daisy, and mingimingi (Coprosma propinqua). Small-leaved divaricating olearia species support a complex array of lichens, mosses and algae on their twigs and stems. These are food for the larvae of 41 moth species known only in New Zealand.
At least 700 species of native fungi are found in mānuka shrublands, where they live in a beneficial association with mānuka.
Birds and lizards
Open shrublands provide shelter and a nesting habitat for banded dotterels and the New Zealand pipit. New Zealand falcons hunt in shrub country, and green finches, hedge sparrows and brown creepers nest in subalpine shrubs. Kea feed on fruit and insects in subalpine scrub.
A number of skinks and geckos also inhabit shrublands. They eat small invertebrates, and seasonal fruits from the shrubs. Lizards spread seeds in shrublands, especially those of coprosma fruits, a favourite food.
Beneficial effects of shrublands
On steep, erosion-prone soils, shrublands protect the land against slips.
Secondary shrublands, of both native and introduced plants, provide shelter and act as a nursery for regenerating forest. They are an effective carbon store, holding around 15.5 tonnes of carbon per hectare. This increases to about 212 tonnes of carbon per hectare as the shrublands develop into mature forest. Carbon accumulation by mānuka is similar to that of fast-growing pine plantations.
Mānuka and kānuka are major sources of honey. Some mānuka honey with high antibacterial activity is used in a range of medical products. Kānuka scrub can be sustainably harvested as firewood, although in the early 2000s, mānuka and kānuka firewood for sale was from clearfelled stands.
There are no national regulations for the protection of shrublands, apart from those covered by the Resource Management Act. Between 1997 and 2002, 12,415 hectares of native shrubland and scrub were cleared for pasture or conversion to forestry.