The ecology of the Hut Valley: Some ecological aspects of the Hutt Valley as an animal habitat
This study examined whether the diversity and relative abundance of ground-dwelling invertebrates changed in relation to type of vegetation cover. Invertebrate taxon diversity and relative abundance were assessed with pitfall traps placed under the native shrubs Olearia bullata and Coprosma propinqua, and in surrounding patches of exotic pasture. A total of 1935 invertebrates and at least 152 invertebrate taxa were recorded from 49 pitfall traps. The number of native taxa was c.63% of all taxa recorded, whereas exotic invertebrates represented only c.9%.
Although invertebrates play a key role in the environment, their conservation and use in environmental monitoring is often considered too difficult and consequently ignored. One of the main problems in dealing with invertebrates is that even limited sampling can yield large numbers of specimens and an enormous diversity of species. Other problems include the taxonomic impediment (i.e.
Artificial refuges and mark-recapture techniques were used to monitor the non-target impacts of handbroadcast application (simulating aerial application) of Wanganui No.7 cereal-based baits containing 0.15% (1500 µg g-1) 1080 on populations of weta and other invertebrates in Tararua Forest Park, North Island, New Zealand. Wellington tree weta (Hemideina crassidens) and a cave weta (Isoplectron sp.) were the only species of weta that occupied the refuges.
Despite the global importance of New Zealands invertebrates, relatively little is known about them and their relationships with plants and plant communities in native habitats. Invertebrate diversity was examined by beating randomly chosen shrubs of the species Olearia bullata (Asteraceae) and Coprosma propinqua(Rubiaceae). Invertebrate taxon richness was assessed initially using morphospecies, which were identified subsequently by expert taxonomists. Though the taxon richness of invertebrates recorded from O. bullata was not significantly higher than that on C.
Assays for the toxin sodium monofluoroacetate (compound 1080) were undertaken on arthropods collected from toxic baits after a brushtail possum (Trichosorus vulpecula) control operation in Nothofagus forest in central North Island, New Zealand. The 1080 concentrations measured (mean 57 mu g per g, max 130 mu g per g) are considerably higher than those reported by other researchers who collected arthropods randomly after control operations.
This study was initiated in response to concerns that vertebrate pest control operations in New Zealand may be having deleterious impacts on invertebrate populations and, secondarily, on insectivorous non-target vertebrate populations. Invertebrates feeding on non-toxic baits of the types used for vertebrate pest control were collected and identified. The bait types were diced carrots and three types of cereal-based baits (No.7, RS5, and AgTech).
Insect communities from a range of successional vegetation stages on the central North Island volcanic plateau were characterised and compared using Malaise trapped beetle samples. Results were derived from sampling series conducted in a total of ten sites over three separate summers. Divisive classification successfully grouped samples according to four main habitat types despite temporal and spatial separation of samples within these groups. A four-week period in early summer was found to be optimum for sample discrimination according to the main vegetation types.
Biological and physical disturbance has had a severe impact on New Zealand's endemic flora and fauna. Along with the lessons of the past, predicting the sensitivity of communities to disturbance in the future may help direct more attention to those communities with a greater need for preservation (i.e., a lower ability to recover from any such disturbances). In theory it is possible to measure the resilience (or local stability) of a community by constructing a matrix to describe that community and then examining its eigenvalues.
Tree trunks are important links between the forest floor and canopy, especially for flightless invertebrates that move from the forest floor to feed or breed in the canopy. Traps were used to sample invertebrates moving up and down on mahoe (Melicytus ramiflorus), hinau (Elaeocarpus dentatus), hard beech (Nothofagus truncata), and kamahi (Weinmannia racemosa). In 19 months 22 696 invertebrates were collected. Many unexpected groups e.g.