Fallow deer impacts on Wakatipu beech forest
- New Zealand Forest Surveys, 15 McElwee Street, Napier, New Zealand
- Department of Medicine, University of Otago, P.O. Box 4345, Christchurch
This study uses data from forty-nine 20 m × 20 m permanent plots measured in 1976, 1982, 1989 and 1997-2002 in Wakatipu Forest, western Otago. We relate changes in red (Nothofagus fusca), silver (Nothofagus menziesii) and mountain beech (Nothofagus solandri var. cliffortioides) forest vegetation to the presence of fallow deer (Dama dama). Vegetation composition is likely to have been altered prior to plot establishment, and results show that there was little change in vegetation composition during the study. There are some signs of fallow deer reducing silver beech seedling abundance at some plots, but most beech stands appear to be in the late phase of development and undergoing self thinning, so are probably not immediately vulnerable to suppression of canopy regeneration. In the future, widespread disturbance is likely to release plants in the understorey from competition for light and nutrients, and at that stage fallow deer browsing of beech species may be able to alter successional pathways more than has occurred over the past two decades. Seedling and sapling density of the palatable Griselinia littoralis (broadleaf) was probably insufficient to ensure successful regeneration. Comparisons of seedling densities with other mixed beech forests throughout New Zealand suggest that fallow deer density will need to be nearly zero in Wakatipu Forest before regeneration of all palatable subcanopy hardwood species is assured.