Spatial modelling of Dragonfly habitats in New Zealand (Odonata : Insecta)

While New Zealand is poor in Odonata species the seventeen species thus far established have great natural importance (Moore 1989). Ten of them are endemic to the islands representing the country. Those include four genera known to occur only in this part of the world (Rowe 1987). This poses a great responsibility on New Zealand to protect this natural treasure. Damselflies and dragonflies are considered well protected within the national parks, but the loss of habitats could severely impact them in the future. This suggests that a habitat assessment should be prepared for the whole country that will serve as base-line data set for monitoring the development of the natural environment for the Odonata species in New Zealand. Fourteen species have been selected for this analysis. Their biological features and ecological requirements were considered in preparing a working habitat assessment methodology. Habitat models were developed using ArcGIS 9.2 software. Multistep spatial analysis was carried out to reclassify the layers containing the important information on the land topology representing crucial elements in the Odonata species habitats. The final outputs are individual species maps where the New Zealand territory is marked with four different colour classes corresponding to the ranks of importance that each area is considered to have for individual species. The models are named probabilistic in that they reveal the areas where the ecological demands of the species are approached at a maximum level. However, they should not be used as distribution maps. Probabilistic models are contrasted against deterministic models used in other Odonata habitat models. The strengths and weaknesses are discussed and some important conclusions and recommendations are described and suggested.