Systemic Feedbacks in Global Land Use

Abstract

Land is a key resource, not only for human societies but also for all organisms—animals, plants and microorganisms—that inhabit terrestrial ecosystems worldwide. Humans use land for at least three purposes: resource supply, waste repository and living space (i.e., the area required for production, consumption, transport, recreation and many other activities). Land use involves the ‘colonization of ecosystems’, that is, purposive interventions into terrestrial ecosystems that aim to support these functions, usually by transforming natural into managed ecosystems (e.g., agro-ecosystems, managed forests, urban systems). Increasingly, land use also aims at other services, such as the conservation of habitats, species or ecosystems or increased carbon sequestration. Maximization of one function, such as biomass supply, often affects other functions, such as carbon sequestration or conservation. Along with the growth of the world population and its per-capita consumption, trade-offs among different functions are becoming more important. A particularly relevant example is the trade-off between food and fuel that has become apparent in the last few years as policies promoting bioenergy on agricultural lands have gained momentum. Although some of these trade-offs can only be mitigated but not completely avoided (e.g., biomass production requires limited resources such as productive area and water), a sociometabolic approach can help identify potential synergies. For example, the use of wastes, by-products and residues (‘cascade utilization’) may help to increase biomass use efficiency and generate several outputs without resulting in resource competition. This chapter discusses such trade-offs and synergies in global land use with a view toward issues of resource supply (mainly food and energy) as well as various ecological conservation aspects (e.g., biodiversity conservation, carbon sequestration and environmentally less-demanding agricultural technologies).