An integrated approach is needed for managing land, water, and eco systems that acknowledges the multi functionality of agroecosystems in supporting food production and ecosystem resilience
feedback effects on food and fiber production [well established]. In extreme cases human health can also suffer, for example, through insect-borne disease or through changes in diet and nutrition. All too often the consequences of modifying agroecosystems have not been fully considered nor adequately monitored.
It has been increasingly recognized that agricultural management has caused some ecosystems to pass ecological thresholds (tipping points), leading to a regime change in the ecosystem and loss of ecosystem services. Ecosystem rehabilitation is likely to be costl , if possible at all. Some changes can be nearly irreversible (for example, the establishment of anoxic areas in marine water bodies). ese changes can occur suddenl , although they often represent the cumula- tive outcome of a slow decline in biodiversity and reduced ecological resilience (the ability to undergo change and retain the same function, structure, identit , and feedbacks).
e poor people in rural areas who use a variety of ecosystem services directly for their
livelihoods are likely to be the most vulnerable to changes in ecosystems. erefore, failure to tackle the loss and degradation of ecosystems, such as that caused by the development and management of agriculture-related water resources, will ultimately undermine progress toward achieving the Millennium Development Goals of reducing poverty, combating hunger, and increasing environmental sustainability.
An integrated approach is needed for managing land and water resources and ecosystems that acknowledges the multifunctionality of agroecosystems in supporting food production and ecosystem resilience. at requires a better understanding of how agroecosystems generate multiple ecosystem services and of the value of maintaining biodiversity, habitat hetero- geneity, and landscape connectivity in agricultural landscapes. Social issues, such as the importance of the role of gender in management decisions, also require more emphasis. Attention should be directed toward minimizing the loss of ecosystem resilience and build- ing awareness of the importance of cumulative changes and of extreme events for generat- ing ecosystem change. It is also necessary to meet the water requirements for sustaining ecosystem health and biodiversity in rivers and other aquatic ecosystems (marshes, lakes, estuaries) and to demonstrate the benefits of these services to society as a whole.
It has been estimated that by 2050 food demand will roughly double. As populations and incomes increase, demand for water allocations for agriculture will rise. Simplified, there are three main ways in which this increased water requirement can be met: through increased water use on current agricultural lands, through expansion of agricultural lands, and through increased water productivity. While all are plausible and a mix of solutions is likel , each has vastly different implications for nonagricultural ecosystems and the services they generate.
With the current high levels of land conversion and river regulation globall , greater con- sideration should be given to improving management of water demand within existing agri- cultural systems, rather than seeking further expansion of agriculture. Dependent on local conditions, technologies and management practices need to be substantially improved, and ecologically sound techniques implemented more widely to reduce the impacts from agriculture, whether extensive or intensive. Further intensification will require careful management to prevent further degradation and loss of ecosystem services through in- creased external effects and downstream water pollution. With the basis of many essen- tial ecosystem services already seriously undermined, there is an urgent need not only to