Chatham Islands threatened birds: recovery and management plans DOC Publication
- Author
- Aikman, H.; Davis, A.; Miskelly, C.M.; O'Connor, S.; Taylor, G.A.
- Year
- 2001
- Journal / Source
- Threatened Species Recovery Plan
- Publisher / Organisation
- Department of Conservation
- Pages
- 20
- Keywords
- ecosystem classification, climate variables, New Zealand, conservation planning, vegetation maps
- Summary
- The need to classify New Zealand's diverse and complex ecosystems is driven not only by scientific curiosity, but also by increased land use planning activity. The classification of ecosystems, as opposed to vegetation, involves the description of relationships between the abiotic environment and its biotic overlay. Although the use of modern quantitative approaches to ecosystem classification would be a preferred option, these have had limited development and application across the full range of biodiversity in New Zealand. Therefore, recognising the need to incorporate physical variables, process variables and biota, we initially constructed a subjective, theoretical framework of environmental or physical drivers in New Zealand. This resulted in a three-variable hierarchy of temperature, moisture availability, and landform and soil gradients, which were divided sequentially down into categories or environmental classes. Vegetation classification literature and expert opinion were then used to align vegetation communities and ground cover classes with each of these environmental zones. A primary division within this classification was the conceptual distinction between zonal and azonal ecosystems, where zonal ecosystems are driven primarily by the physical, macroclimatic variables of temperature and moisture availability, and azonal ecosystems are primarily the product of process variables producing edaphic extremes (e.g. extreme rock and soil chemistry, extreme heat, and frequent disturbance). Thus, for the azonal section of the classification, the three-variable abiotic framework was applied after these additional process variables, which included geomorphic disturbance, frequent fire, geothermal heat and extreme soil chemistry. In total, this classification led to 152 ecosystems being recognised