ecosystem processes

We estimated the annual production of honeydew per unit land area of beech (Nothofagus spp.) forest by measuring the amount of honeydew produced in 24 h by scale insects (Ultracoelostoma spp.) (Hemiptera: Margarodidae) every month for 2 years. We used exclosures to prevent animals (notably Vespula wasps) removing honeydew, and we compared the standing crop of honeydew inside permanently closed exclosures with that outside exclosures.

We agree with Williams’ (2003) response to our previous paper (Dungan et al., 2002) whereby data is presented in support of the contention that we overstated our argument that possums may be the only dispersal vector for large–seeded native New Zealand species. We contend that this does not alter our overall conclusions, but agree that additional work is needed to balance any potential positive effects of possums as seed dispersers against their significant negative impacts on forested ecosystems.

New Zealand’s offshore islands are refuges for many threatened species, a high proportion of vertebrate diversity, and the world’s most diverse fauna of seabirds. We present key issues and questions that can be used to guide research on the conservation of biodiversity on these islands. Four global reviews formed a basis from which we identified research questions of potential relevance to the management of these islands. The research questions were assigned in the context of nine objectives proposed as a means of achieving ecological integrity.

Invasive weeds have been shown to alter ecosystem processes such as decomposition and nutrient cycling. However, little is known about the effects of introduced biocontrol agents on these processes. This study examined the effects of alligator weed (Alternanthera philoxeroides) and its biocontrol agent, the alligator weed flea beetle (Agasicles hygrophila), on nutrient cycling in a northern New Zealand lake.