Options for enhancing forest biodiversity across New Zealand’s managed landscapes based on ecosystem modelling and spatial design

In most regions of the world removal of environmental stress facilitates regeneration of native plants and habitats. However, in many of New Zealand’s modified landscapes, exotic species are likely to respond first to any reduction in stress because these fast-growing species are prevalent in local vegetation and dominate seed banks. Given the trend in agriculture towards intensive management on larger units, the indigenous character in New Zealand landscapes is being marginalised and there is the risk that further reduction in visibility of native vegetation may be perpetuated by a growing familiarity and identification with ubiquitous exotic species. Alternative landscapes, based on an understanding of ecosystem processes, need to be explored if biodiversity goals set by international convention and national resource management law are to be achieved. This study provides a set of predictions and pathways, backed by field observations, to underpin a restoration strategy at patch to landscape scales. A forest model, LINKNZ, is employed to simulate species succession under New Zealand conditions. The incorporation of disturbance regimes and species dispersal processes in the model permits a wide range of scenarios to be investigated encompassing indigenous forest development, exotic species interactions with indigenous forest ecosystems, management of mixed introduced-indigenous forests, and landscape dynamics. The results illustrate an approach that identifies potential biosecurity threats and provides additional options for integrating nature and production in New Zealand’s rural and urban landscapes. ____________________________________________________________________________________________________________________________________