<I>Agathis australis</I>

Home range dimensions and habitat use by ship rats (Rattus rattus) at Puketi, a kauri (Agathis australis) forest in Northland, were examined by live capture and radio-tracking over five weeks in September and October 1993. Home ranges of six females and five males averaged 0.86 ha in area and 174 m in length, with no significant difference in range area or length between males and females. There was substantial overlap in ranges between and within sexes.

The data of Lloyd (1971) on the 'chosen tree' and 'chosen seedlings' in 5607 4 x 4 m plots in Russell forest are analysed using a simple transition matrix model. The most realistic analysis predicts little change in relative species composition, other than a slight increase in the softwoods. The virtue of the approach lies more in the questions it raises than in the predictions obtained. Before such models can be applied satisfactorily in New Zealand basic data on seedling survival, tree growth rates and average life spans are required for most indigenous species.

Host bark traits are known to affect the characteristics of epiphyte communities in forests worldwide; however, few investigations of such relationships have been undertaken in New Zealand forests. By examining the trunk epiphyte communities on four co-occurring forest tree species (Agathis australis, Dacrydium cupressinum, Knightia excelsa and Vitex lucens) representing a range of bark characteristics, we sought evidence that bark traits may shape these communities. Sampling was conducted on tree trunks in the Waitakere and Hunua ranges in the Auckland Region.

It has been suggested that plants can change soil characteristics via their litter to favour their own species. The New Zealand kauri tree (Agathis australis) presents an interesting case for studying such a positive feedback between plant and soil because it has a huge impact upon the soil. We hypothesised that, under mature kauri trees, compared with sites outside the projection of the crown, seedlings of angiosperm trees are relatively rare, while kauri seedlings are relatively common, due to the poor soil conditions and the higher light intensity.

Plants can change the soil that they grow on, for example by producing litter. If litter characteristics are such that their effect on the soil increases a plant's fitness, a positive feedback can develop between the plant and the soil. Several studies indicate that New Zealand kauri trees (Agathis australis) lower the availability of nutrients in the soil beneath their crown. Low nutrient availability would be positive for the survival of kauri seedlings as they are known to use nutrients more efficiently than angiosperm species.