seedlings

Floristic boundaries, where the range limits of multiple species coincide, are frequently recognised ecological phenomena for which underlying mechanisms are often unclear. Plant species range limits are often determined by their tolerance to climatic conditions. Therefore, the positions of floristic boundaries are also likely related to climatic conditions. Seedlings are a vulnerable life stage and are often highly susceptible to adverse climatic events such as frosts, and frost susceptibility varies among plant species.

The advent of mammal-resistant fences has allowed multi-species eradications of mammals from ecosanctuaries on the New Zealand mainland. However, maintaining eradication of house mice (Mus musculus) has proven difficult, and at some fenced reserves they are the only exotic mammal present and reach a high population density. Over 5 years we examined the impacts of mice alone on biodiversity at Sanctuary Mountain Maungatautari by comparing forest blocks with relatively high and low numbers of mice.

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.

[First paragraph(s)...]
“A freezing chamber offers an easy place for such [frost] experiments... and ... valuable data as to the cold-resisting powers of our plants might be arrived at” (Cockayne, 1897).

Variation in seedling growth and form between provenances of Podocarpus totara from 42 sites throughout New Zealand was investigated. Seedlings were grown for three years under uniform nursery conditions. There were significant differences between provenances in height growth in the first three years after sowing. Early growth was highly correlated with germination rate after sowing. In the third year, growth followed a different pattern and was negatively correlated with provenance latitude, i.e., provenances from southern latitudes grew more slowly than those from further north.