Human appropriation of net primary production (HANPP), the aggregate impact of land use on biomass available each year in ecosystems, is a prominent measure of the human domination of the biosphere. We present a comprehensive assessment of global HANPP based on vegetation modeling, agricultural and forestry statistics, and geographical information systems data on land use, land cover, and soil degradation that localizes human impact on ecosystems. We found an aggregate global HANPP value of 15.6 Pg C/yr or 23.8% of potential net primary productivity, of which 53% was contributed by harvest, 40% by land-use-induced productivity changes, and 7% by human-induced fires. This is a remarkable impact on the biosphere caused by just one species. We present maps quantifying human-induced changes in trophic energy flows in ecosystems that illustrate spatial patterns in the human domination of ecosystems, thus emphasizing land use as a pervasive factor of global importance. Land use transforms earth's terrestrial surface, resulting in changes in biogeochemical cycles and in the ability of ecosystems to deliver services critical to human well being. The results suggest that large-scale schemes to substitute biomass for fossil fuels should be viewed cautiously because massive additional pressures on ecosystems might result from increased biomass harvest.biomass ͉ global environmental change ͉ human impact ͉ biosphere ͉ land use

Global increases in population, consumption, and gross domestic product raise concerns about the sustainability of the current and future use of natural resources. The human appropriation of net primary production (HANPP) provides a useful measure of human intervention into the biosphere. The productive capacity of land is appropriated by harvesting or burning biomass and by converting natural ecosystems to managed lands with lower productivity. This work analyzes trends in HANPP from 1910 to 2005 and finds that although human population has grown fourfold and economic output 17-fold, global HANPP has only doubled. Despite this increase in efficiency, HANPP has still risen from 6.9 Gt of carbon per y in 1910 to 14.8 GtC/y in 2005, i.e., from 13% to 25% of the net primary production of potential vegetation. Biomass harvested per capita and year has slightly declined despite growth in consumption because of a decline in reliance on bioenergy and higher conversion efficiencies of primary biomass to products. The rise in efficiency is overwhelmingly due to increased crop yields, albeit frequently associated with substantial ecological costs, such as fossil energy inputs, soil degradation, and biodiversity loss. If humans can maintain the past trend lines in efficiency gains, we estimate that HANPP might only grow to 27-29% by 2050, but providing large amounts of bioenergy could increase global HANPP to 44%. This result calls for caution in refocusing the energy economy on land-based resources and for strategies that foster the continuation of increases in land-use efficiency without excessively increasing ecological costs of intensification.agriculture | food | land use intensity | resource use | global carbon cycle A lthough planet earth is finite, the growth of world population and economic activity result in an increasing demand for natural resources and ecosystem services. Concerns about these trends have motivated prominent scholars to define a new geological era, the "anthropocene" (1, 2). Changes in land use are particularly pervasive (3, 4) because human activities now affect approximately three-quarters of all vegetated lands (5). In the next four decades, population is expected to grow by 40% (6), the world economy could grow by a factor of 3 over its present value (7), and agricultural production is expected to grow by 60-100% (8, 9). Moreover, influential energy strategies advocate expanding bioenergy severalfold from its present value of ∼50 exajoule (EJ)/y (10, 11). At the same time, there are concerns that humanity is already outside its safe operating space in terms of nitrogen use, climate change, and biodiversity loss and near other critical limits such as land use (12) or biomass production of green plants (13). The ability of humanity to respect planetary boundaries (12) will depend on its ability to decouple growth from its demand for resources (14).The capacity of land to produce biomass is one critical limiting resource (13). Although humans can influence that capacity through inputs and manag...

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