A landscape approach for assessing the biodiversity value of indigenous forest remnants: Case study of the Manawatu/Wanganui region of New Zealand

To halt the decline of biodiversity in New Zealand, the government has formulated a strategy of maintaining and restoring a full range of remaining natural habitats to a healthy functioning state. Many indigenous forest remnants exist on private land, and these could be utilised to increase biodiversity. Resources for conservation of forest remnants are limited, so they must be used wisely to deliver the greatest possible biodiversity gain. This paper presents a rapid method for valuing the biodiversity of a region's indigenous forest remnants to help prioritise conservation resources. The region is divided into environmentally distinct areas called land environments. A detailed land-cover map is derived from satellite imagery and used to estimate the proportion of natural habitats remaining in each land environment; from this the biodiversity value of any forest remnant may be calculated. The method is rapid and does not require detailed biodiversity information. When combined with conservation costs, it may be used to create a priority list of forest remnants for conservation. The Manawatu/Wanganui region of New Zealand is used as a case study to demonstrate the method.