Wetland processes and data storage, with particular reference to Great Barrier Island Other Publication
- Author
- Ogden, J.
- Year
- 2009
- Journal / Source
- Lucy Cranwell Lecture for 2009
- Pages
- 85-92
- Summary
- The wetlands of New Zealand are diverse ecosystems which have suffered massive decline due to man’s activities. Much of this (e.g. drainage) has been obvious and intentional, but some, such as increased sedimentation rates following forest clearance, has been long-term and insidious. These processes are described with examples from Great Barrier Island. I emphasise the role of wetlands as systems which store environmental data about the past and integrate processes from whole catchments. Hydroseral succession and the development of raised bogs are described, and a few important terms explained. The abundance of wood in bogs in New Zealand is noted and its significance as a climatic data store referred to. Rates of sedimentation and peat accumulation are presented. At Whangapoua estuary, mangroves (Avicennia marina), are succeeded by open herbaceous communities (salt meadow) at their landward edges. The succession from open seawater, through mangroves and salt meadow to oligotrophic manuka (Leptospermum scoparium) swamp is described. Eutrophic communities, mostly dominated by Typha orientalis, occur in the fresh-water streams feeding into the system. The significance of Baumea juncea, as a switch plant, facilitating the transition from marine to freshwater communities is emphasised.