edge effect

Non-native species have the ability to negatively impact ecosystems, and the recipient biodiversity they may invade. However, they must first go through a series of abiotic and biotic filters that limit their ability to spread once established, which ultimately influences their distribution across different habitats. By understanding which habitats are most vulnerable to invasion, pest managers can prioritise their surveillance areas to focus on those most at risk.

Forest vegetation patterns alongside the Poerua River, south Westland, were studied to determine whether a distinct riparian community could be defined either immediately adjacent to the river, or out to the limit of overbank flooding. Ten randomly located 100 m transects were established perpendicular to the river at each of two sites. Ground cover of alluvial sediment indicated that annual overbank flooding occurred up to 20 m into the forest (the flood zone).

This study examined how forest edges influenced leaf and floral herbivory, as well as seed predation, in a native New Zealand mistletoe species, Alepis flavida. Plants growing on forest edges and in forest interior were compared, and effects of plant size and the neighbouring conspecific plant community were also examined. Leaf herbivory by possums was significantly greater on forest edges than in forest interior in a year of high possum damage, but not in a year with low damage levels. Insect leaf herbivory did not differ between forest edges and interior.

This study examined how forest edges, fruit display size, and fruit colour influenced rates of seed dispersal in an endemic, bird-dispersed, New Zealand mistletoe species, Alepis flavida. To examine rates of seed dispersal, fruit removal rates were compared between plants growing on forest edges and in forest interior, and also between two morphs of plants with different coloured fruits. Two aspects of fruit display size were examined: plant size and the neighbourhood of conspecific plants.