Regeneration in indigenous forest after eradication of Norway rats, Breaksea Island, New Zealand

Abstract

Population age structures and recruitment of major tree and shrub species on Breaksea Island, Fiordland, New Zealand, were assessed at the time of eradication of Norway rats in 1988 and over the following 5 years. Seedling numbers of many tree and shrub species increased substantially over the period 1988–1993 after rat eradication. Population age structures of the dominant trees Nothofagus menziesii and N. solandri var. cliffortioides suggested a lapse of recruitment starting about 100 years ago, coinciding with the probable time of rat establishment. The recruitment gaps, and increases in seedling numbers are circumstantial evidence that rat predation was an important constraint on plant regeneration on Breaksea Island.