forest dynamics

The ecological impacts of feral pigs (Sus scrofa) are of concern in many places around the world. One noticeable impact is soil disturbance, although the causes and consequences are often unclear. We measured the effect of ground disturbance by feral pigs on seedling recruitment and soil ecology over 25 months on a forested riparian terrace at Waitutu, south Fiordland, New Zealand, and assessed the diet of pigs from the area from stomach contents of animals shot by hunters. Foraging by feral pigs for below-ground food disturbed between 7.4% and 12.4% of the soil.

A population of red beech (Nothofagus fusca) seedlings was studied in a forest dominated by red beech but apparently with little regeneration. Estimates of the germination, growth and survival rates of seedlings growing on different microsites were obtained in three, one hectare stands over a one year period and the size and age structure of the population examined. Irregular and sometimes massive seedfalls occur but some seedlings establish at least every two or three years.

The population structure of red beech (Nothofagus fusca) is described for four forest stands situated at different altitudes on Mount Colenso. Data on red beech seedling densities and frequency distributions of living and dead tree diameters (d.b.h.) are presented. Red beech seedlings are shown to be more numerous, and on average larger, on decaying red beech logs than elsewhere. This seedling site preference could lead to, a 'regeneration cycle', and explain the 'regeneration gaps' and bimodal d.b.h. frequency distributions commonly found in red beech forest in the Ruahine ranges.

We examine the height growth, diameter growth and below-ground allocation responses of mountain beech (Nothofagus solandri var. cliffortioides) seedlings to the experimental removal of root competition through root trenching and the addition of fertiliser within relatively intact-canopied mountain beech forest in the Craigieburn Range, Canterbury. Trenching and trenching combined with fertiliser increased relative height and diameter growth of mountain beech seedlings above that of controls.