How well is space-time variability of GPP represented within Australia’s nature conservation reserves (NCRs)?
A primary aim of conservation reserve systems is to protect biodiversity through conservation of a range of natural environments. Within natural environments the biotic diversity is moulded by, among other things, the spatial and temporal availability of resources for photosynthesis. The net rate at which carbon and energy are assimilated by photosynthesis, or gross primary productivity (GPP), can be estimated from time-series of remotely sensed data. In this study we investigate how well the natural variability in GPP is represented within the NCR system.
Using established methods we estimated monthly GPP over Australia for the period July 2000 to June 2005 at 250m × 250m spatial resolution. For this study we calculated the mean annual GPP, the between year standard deviation, and the minimum annual GPP for the 5 years of data. We analysed these data at the regional scale (following the IBRA regionalisation) using a within region hierarchical classification of the pixels according to (i) biophysical naturalness and (ii) land tenure (NCR or not NCR).
The area designated as NCR in this study comprised 8.4% of the Australian continent, and 10.6% of the mean continental GPP. Preliminary analyses suggest that in about half of the IBRA regions, vegetation types having lower mean GPP tend to be underrepresented in Australia’s NCRs, whilst in a quarter of the regions vegetation types having higher GPP tend to be underrepresented.