Net Ecosystem Productivity

Net Ecosystem Productivity (NEP) may act as a surrogate for many ecosystem services given the crucial role of photosynthesis for many, if not all, ecosystem services. This indicator is based on NDVI measurements by Spot Vegetation. NDVI data were taken for 2009, 2010 and 2011. The Phenelo algorithm was used to calculate productivity based on seasonal vs. non seasonal vegetation, which involves a calculation of growing season biomass for those vegetated surfaces which exhibited seasonal variations. For each map, the upper and lower 90 percentile were set as maximum and minimum to avoid outliers due to e.g. satellite sensor acquisition error and subsequently the data were scaled between 0 (lower 90 percentile) and 1 (upper 90 percentile) to give a more apprehensive measure of standing biomass. Next, for each set of three years an annual average was calculated to reduce the effect of annual variation on primary production.