Vulnerability of Indigenous Forests in Changing Landscapes

Abstract

Indigenous forests all over the world are suffering habitat alteration, loss of original extensions, and increase of isolation levels, affecting their existence and sustainability. In New Zealand about 70% of the original forest cover has been destroyed since human settlement, converting them to a rare and threatened resource. Part of the problem is because native forests are often immersed in a landscape where other land uses are competing for the same space. Effective conservation management of these indigenous forest remnants requires information about their vulnerability to threats, in space and time. Few studies provide an integrated assessment of the extent to which socio- economic effects are responsible for native vegetation vulnerability and how these relationships change through time. In this study socio-economic drivers at different scales are related to land cover changes. To analyse vulnerability of indigenous forests a temporal dataset was developed from aerial photography for the years 1942, 1961, 1984, and satellite images for the years 1999 and 2006. They were managed within a GIS, recording the extent and distribution of these forests and other principal land covers in a study area of ca. 80,000 ha in the Northland region. Information about incentives to land production and to conservation was compared to changes of composition, configuration and conversion of land cover. Spatial conditioners of change, such as elevation, land use capability and land legal protection, were also assessed as possible constrainers of indigenous forest loss. Results showed that the incentives to land production had changed their significance for vulnerability of indigenous forests through time. These became conditioned by other land covers and incentives to conservation, and besides, indigenous forest was a quite stable cover where the physical characteristics of their location were unsuitable for land production. I concluded that at scale of decades, changes in area of indigenous forest were reversible; non- linear; driven by political, institutional and economic changes but that, biophysical characteristics of the landscape can preclude conversion. Such conclusions may help to set priorities for the long term protection and management of indigenous forests.