Agroecosystems are the ecosystems supporting the food production systems in farms and gardens. As the name implies, at the core of an agroecosystem lies the human activity ofagriculture. As such they are the basic unit of study inAgroecology, andRegenerative Agriculture using ecological approaches.
Like other ecosystems, agroecosystems form partially closed systems in which animals, plants, microbes, and other living organisms and their environment are interdependent and regularly interact. They are somewhat arbitrarily defined as a spatially and functionally coherent unit of agricultural activity.[1]
An agroecosystem can be seen as not restricted to the immediate site of agricultural activity (e.g. thefarm). That is, it includes the region that is impacted by this activity, usually by changes to the complexity ofspecies assemblages andenergy flows, as well as to thenet nutrient balance. Agroecosystems, particularly those managedintensively, are characterized as having simplerspecies composition, energy and nutrient flows than "natural" ecosystems.[2] Likewise, agroecosystems are often associated with elevated nutrient input, much of which exits the farm leading toeutrophication of connected ecosystems not directly engaged in agriculture.[3]
Forest gardens are probably the world's oldest and most resilient agroecosystem.[4]
Some major organizations are hailing farming within agroecosystems as the way forward for mainstreamagriculture. Current farming methods have resulted in over-stretched water resources, high levels oferosion and reducedsoil fertility. According to a report by theInternational Water Management Institute and theUnited Nations Environment Programme,[5] there is not enough water to continue farming using current practices; therefore how critical water, land, andecosystem resources are used to boost crop yields must be reconsidered. The report suggested assigning value to ecosystems, recognizing environmental and livelihood tradeoffs, and balancing the rights of a variety of users and interests, as well addressing inequities that sometimes result when such measures are adopted, such as the reallocation of water from poor to rich, the clearing of land to make way formore productive farmland, or the preservation of awetland system that limits fishing rights.[6]
One of the major efforts of disciplines such asagroecology is to promote management styles that blur the distinction between agroecosystems and "natural" ecosystems, both by decreasing theimpact of agriculture (increasing the biological and trophic complexity of the agricultural system as well as decreasing the nutrient inputs/outflow) and by increasing awareness that "downstream" effects extend agroecosystems beyond the boundaries of the farm (e.g. theCorn Belt agroecosystem includes thehypoxic zone in the Gulf of Mexico). In the first case,polyculture orbuffer strips for wildlife habitat can restore some complexity to a cropping system, whileorganic farming can reduce nutrient inputs. Efforts of the second type are most common at thewatershed scale. An example is theNational Association of Conservation Districts'Lake Mendota Watershed Project, which seeks to reduce runoff from the agricultural lands feeding into the lake with the aim of reducingalgal blooms.[7]
