invasions

Changes in Hieracium abundance in Eastern Otago tussock grassland were examined by sampling 163 sites in 1982 and again in 1992. For Hieracium pilosella, H. praealtum and H. lepidulum, as well as Agrostis capillaris for comparison, colonisation of new sites was recorded, as well as extinction of species from sites over the 10 years, and changes in cover. H. pilosella colonised the majority of sites from which it had been absent in 1982; it disappeared from only a few sites where it had been present at very low cover.

Introduced common wasps (Vespula vulgaris) are widespread, abundant pests in New Zealand. They compete for food with native birds and feed on native invertebrates. We poisoned wasps annually over 4 years to see if it was possible to reduce their abundance in two 30-ha beech forest sites. Two different poisons (sodium monofluoroacetate and sulfluramid) were used, mixed with sardine catfood. There was no evidence that one poison was more effective than the other.

We outline the scope of this special issue of New Zealand Journal of Ecology, which reviews progress in New Zealand ecology to 2009, based on a symposium in 2007. Both the issue and symposium update a 1986 conference and 1989 special issue of NZ J Ecol called “Moas, Mammals and Climate” which has been influential and widely cited.