Growing world population and increasing wealth are driving demands for more food production. Croplands and pastures occupies today roughly 40% of the land surface and global land cover and is according to the Millennium Ecosystem Assessment (MA) the main modification humanity makes to land cover, and therefore a main driver of ecological change, and biodiversity loss at the global scale.
In a new paper in Science, Jonathan Foley et al. reviews the Global Consequences of Land Use , and discuss consequences of land use on food production, water resources, forests, regional climate and air quality and infectious diseases. They highlight the challenge of managing trade-offs between immediate human needs and maintaining the capacity of the biosphere to provide goods and services in the long term.
Current trends in land use allow humans to appropriate an ever-larger fraction of the biosphere’s goods and services while simultaneously diminishing the capacity of global ecosystems to sustain food production, maintain freshwater and forest resources, regulate climate and air quality, and mediate infectious diseases…
…The conclusion is clear: Modern landuse practices, while increasing the short-term supplies of material goods, may undermine many ecosystem services in the long run, even on regional and global scales. Confronting the global environmental challenges of land use will require assessing and managing inherent trade-offs between meeting immediate human needs and maintaining the capacity of ecosystems to provide goods and services in the future. Assessments of trade-offs must recognize that land use provides crucial social and economic benefits, even while leading to possible longterm declines in human welfare through altered ecosystem functioning.
…Society faces the challenge of developing strategies that reduce the negative environmental impacts of land use across multiple services and scales while maintaining social and economic benefits.
Lepers et al. published recently a study in BioScience illustrating that land use change during the last 20 years has been very rapid. The future looks bleak too.
Land cover change between 1995 and 2050 across MA scenarios from MA (2005).
The figure from the Millennium Ecosystem Assessment illustrates expected future land use changes until 2050 under four different Scenarios. Sub-Saharan Africa (SSA) seems to be particularly problematic, also having a high population growth, scarce and highly variable water resources and soils that are very vulnerable to desertification (MA).
However, Foley et al. also suggest several strategies to improve the situation including, a) increased productivity per unit of land, fertilizer and water, b) maintaining soil organic matter, c) increased green areas in urban landscapes, d) “agroforestry” in the sense of nurturing multiple ecosystem services from agricultural systems, and e) biodiversity and landscape management. They also give a list of win-win situations and conclude by pointing at the need for more cross-disciplinary research, and more interactions among scientists and practitioners. Don’t miss the supplementary information of the paper – it has a lot of interesting things in it.
Figure – Foley et al’s (2005) conceptual framework for comparing land use and trade-offs of ecosystem services. The provisioning of multiple ecosystem services under different land-use regimes can be illustrated with these simple ‘‘flower’’ diagrams, in which the condition of each ecosystem service is indicated along each axis. (Figure 3 in Foley et al 2005)
For more discussions on agriculture and environment, Robertson and Swinton had an excellent review in Frontiers of Ecology and Environment recently called Reconciling agricultural productivity and environmental integrity: a grand challenge for agriculture.
Different valuation strategies for services provided by agricultural ecosystems. On the left are farm products and other services valued by markets and for which price incentives drive human management decisions. On the right are those services that are publicly valued and for which policy incentives drive management decisions. Other services (such as the provision of private recreation) may be only privately valued so that their provision is not rewarded by markets or policy (Figure 5 in Robertson and Swinton 2005).