An ecological study of a New Zealand mainland restoration endeavour : the Northern Te Urewera Ecosystem Restoration Project

Abstract

This study investigated some of the impacts of a New Zealand mainland restoration initiative conducted by the New Zealand Department of Conservation within the mixed broad-leaved podocarp forest of the northern Te Urewera National Park; The Northern Te Urewera Restoration Project. Restoration work in this project focussed on invasive mammalian pest control to allow recovery of bird populations, forest tree and plant species, and forest dynamics. A background control of the invasive brush-tailed possum control was commenced over the entire c. 50,000 ha region of this forest while small core areas received intensive multi-species mammalian pest control. The long term vision of this project is the restoration of the entire c.50,000 ha northern Te Urewera forest region. It is crucial to monitor outcomes of conservation management initiatives; to establish whether these have been successful in meeting goals, to track populations of interest, and to illustrate the outcomes from investment of conservation money and effort. It is also important to develop tools for use in this work. Therefore the primary aim of this study was to attempt to detect the effects of the management regime within the first of the intensively treated core study areas, Otamatuna. This was done through comparisons with a non-treatment study area nearby within the contiguous northern Te Urewera forest, Okopeka. A secondary aim of this research was to explore the application of novel survey techniques during the course of the study. Therefore a multi-pronged investigation was conducted. This incorporated the survey of; forest tree canopy phenology, fruit-fall within ground collections, the height, diversity and age of seedlings, as well as forest bird abundances. Absolute and or relative abundance estimates were estimated for bird species. Results revealed several detectable positive effects of the intensive management regime within Otamatuna. These included indications of forest bird recovery within this site, significantly less predation of fallen forest tree fruit, no detectable possumdisturbance of fruit in the Otamatuna canopy, and greater occurrence of palatable seedlings within this study region. The application of distance sampling techniques in terms of the length of counting period was also explored.