revegetation

The incorporation of native, woody vegetation into New Zealand’s agricultural ecosystems offers a “nature-based solution” approach for mitigating poor environmental outcomes of land use practices, biodiversity loss, and the accelerating effects of climatic change. However, to achieve this at scale requires a systematic framework for scoping, assessing, and targeting native revegetation opportunities in a way that addresses national-scale priorities, supports landscape-scale ecological processes, and recognises that land use decisions are made at farm-scales by landowners.

The low level of plant nutrients in exposed high-altitude subsoils, and the effects of soil frost and needle ice on plants attempting to colonise these subsoils combine to make natural revegetation very difficult. Artificial revegetation trials established in 1965 at three sites in the Canterbury mountains tested the effect of a fertiliser mixture which supplied a wide range of nutrients, and compared ten herbaceous species as providers of an initial protective cover, and of a cover that would persist.

The distribution and abundance of lizards relative to habitat structure were studied at Pukerua Bay, Wellington between December 1982 and March 1988 in order to identify options for management of the habitat of the five species of lizards present. One species, Whitaker's skink (Cyclodina whitakeri), is a threatened species with only one known mainland population. Pitfall traps were set for 23 667 trap-days and yielded 2897 lizard captures. Highest capture rate was for common skinks (Oligosoma nigriplantare polychroma) and lowest rate was for C. whitakeri.

Mana Island (217 ha) provides opportunities for conservation despite over 150 years of farming. It is free from all introduced mammals except mice. It supports native coastal communities representative of the region and already has nationally threatened plants and animals.

The ecological restoration of Tiritiri Matangi Island is a community-driven initiative that has captured the interest of the international conservation movement. Ecological restoration commonly focuses on the establishment and maintenance of functioning indigenous ecosystems through the control or eradication of invasive weeds and animal pests, indigenous species translocations, and habitat enhancement, including revegetation. Revegetation of indigenous plant communities provides an opportunity to kick-start natural processes and facilitate succession towards a diverse ecosystem.

Forty years since the cessation of grazing on Tiritiri Matangi, the island has been transformed by a restoration programme. However, a big question remained: What the island would have looked like if restoration had not occurred? This study addresses that question. Some sections of the island were deliberately not restored and allowed to regenerate naturally to provide a reference point for the changes brought about by direct intervention. In one area a transect of plots was available in which species composition and frequency information had been measured in a pre-restoration state.