Forest regeneration and the influences of white-tailed deer (Odocoileus virginianus) in cool temperate New Zealand rain forests

Cool temperate rain forests on Stewart Island, southern New Zealand, have had little direct human modification, but introduced white-tailed deer (Odocoileus virginianus) have influenced forest understoreys. Changes in life stages (seedlings, saplings and adult trees) of common tree and shrub species were recorded over at least 18 years in permanent plots in these forests. Faecal pellet indices of deer frequency in the forests were slightly greater in the most recent survey. However, during this period overall seedling and sapling densities increased, including species browsed preferentially by deer. In deer exclosures maintained over 21 years, densities of woody seedlings and saplings increased, but not of highly palatable species. While deer frequency was a significant predictor of increased seedling densities of unpalatable species and decreases of palatable species at a plot scale, so also were measures of local seed availability and competition from other seedlings and ferns. Seedling density increases were not uniform across species in response to stand structural attributes, and there were interactions between effects of browsing by deer and stand structural attributes. Therefore, relationships between deer frequency and seedling regeneration need to be set in the context of other biotic influences in these forests. Crown Copyright (C) 2002 Published by Elsevier Science B.V. All rights reserved.