Fragments of kahikatea (Dacrycarpus dacrydioides) forest provide a major opportunity for conservation of indigenous biodiversity in the heavily deforested landscape of the Waikato Basin, New Zealand. However, there is little documented information on what indigenous fauna survives in these fragments.
The spatial distribution of feral ferret (Mustela furo) activity and denning were studied using ink-print tracking tunnels and radio-tracking within pastoral farmland containing a mosaic of grazed (developed and semi-developed) and ungrazed pasture, scrub, tree plantation and scrubby fence lines at Palmerston, East Otago, South Island, New Zealand. Ferrets concentrated their activity in grazed areas but within these areas they were found more often where herbs, scrub and woody cover were present, and where there was an ecotone between pasture and vegetation cover.
Replacing native forests and grasslands with plantations, pastures and crops has resulted in both contraction of ranges and exploitation of modified habitats by native species, and both general and restricted dispersal of introduced species of soil fauna. Contraction is shown by native earthworms, land snails, ring nematodes and various arthropods, while the areas with changed land use suggest certain native insects are more numerous than 150 years ago. Damage to pastures by grass grub and porina show clearly how native species can exploit modified habitats.
Before European settlement, most of the 750,000 ha of land comprising the Canterbury Plains was under native tussock grassland with pockets of podocarp forest. The dominant land use today is mixed cropping in which cereals and cash crops are grown for 2 to 4 years followed by grass-clover pasture for 2 to 4 years. These cropping rotations are generally too short for either a substantial build-up in soil organic matter under pasture or its breakdown under arable cropping to occur.
The improvement of New Zealands pastures over the last 150 years has increased the nutrient status of the soil as a result of the application of fertiliser, an increased soil organic matter content and increased biological activity. The grazing animal has also influenced the nutrient status of the soil by increasing the rate at which nutrients cycle between the soil, plants and animals.
The diet of brushtail possums (Trichosurus vulpecula Kerr) in mixed hardwood forests on a central Westland hillside is described from analysis of plant cuticle fragments and seeds in their faeces. Faeces were collected monthly for 2.25 years from animals live-trapped from low altitude forest/ pasture margins through to high altitude alpine shrublands. The diet included forest and pasture foliage, buds, and fruits of over 100 species, although most were eaten infrequently.