The effect of deer browse on the recruitment of mountain beech (Nothofagus solandri var. cliffortioides (Hook f.) Poole) in the Kaweka Forest Park, North Island, New Zealand

Abstract

The effects of deer browse on seedling populations of Nothofagus solandri var. cliffortioides (mountain beech) were investigated in the high altitude forest in the Kaweka Range, Hawke's Bay, North Island, New Zealand. Seedling height and density were recorded, and rates of height growth and mortality were measured over one year within two fenced deer exclosures, and on adjacent unfenced plots. The paired enclosure plots were established in 1981 at two sites, in stands of different structure. One site was considered critical for regeneration, as canopy collapse had already occurred. Seedling growth rates were higher at each site within the fenced deer exclosure plots. Growth rates were highest under open canopy. Greatest mortality rates were under closed canopy within an exclosure, where seedling densities were high. Variation in seedling height and height growth was poorly explained on all plots, even in the absence of deer browse. Simple models of seedling growth and mortality, based on initial seedling densities, showed that sufficient regeneration would occur on all sites, but recovery would be faster if deer numbers were reduced. High densities of sika (Cervus nippon) and red deer (C. elaphus) have slowed regeneration of mountain beech on sites where the forest canopy has collapsed naturally.