Assessments of HANPP require the calculation of several components of primary production and the changes induced by land use. These components allow additional insights. For example, if land management in a country results in a downward trend of NPPact, this indicates environmental degradation (Munasinghe and Shearer 1995). The relationship between NPPQ and NPPact shows how well agriculture uses the production potential of a region and therefore is an indicator of agricultural area efficiency. The relationship between NPP^ and HANPP reveals how much of the HANPP results from harvest and how much from changes in productivity. Land use may reduce (e.g., urban settlements, infrastructure, erosion) or increase (e.g., irrigation, fertilization) productivity.2
Similar indicators for human-induced changes in the production ecology of terrestrial ecosystems have been proposed. Land use influences the standing crop (the amount of live biomass) of ecosystems, which is relevant for ecological carbon balances (Erb 2004). Land use may also accelerate biomass turnover (= NPP/standing crop/yr) by up to fifty times (Erb 2004; Haberl et al. 2001), with currently largely unknown consequences.
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