The Big Picture Farms as Ecosystems

Organic farming provides ecosystem services as well as food. The weakest points oforganicfarming systems are limited use oflivestock and declining genetic resources. Organic farming has special research and service needs. On-Jarm experimentation is needed to fully optimize each system. Through the 19th and 20th centwies, the Earth's landscape has been fundamentally transfonned. Where we once had nodes ofhuman activity set in a mosaic of naturaI or quasi-natural ecosystems, we now have a mosaic ofhuman settlements, domesticated landscapes, and fragmented natural ecosystems. At the end of the 20th centwy, an agroindustrial model is the nonn for management ofagriculture, and also for residential and recreational lands, silvicultures, and aquacultures. This specialization model separates major components of the fann ecosystem- most notably livestock and crops- for the sake ofproduction efficiency. It substitutes chemical inputs for natural processes such as the return ofnutrients to the land, and control ofpests by natural enemies. Although we generally accept that agroindustrial systems have low "ecosystem value, " we still expect that they should not seriously degrade other ecosystems that provide us with non-costed services (Table 1), estimated to be worth at least twice the world GNP (Costanza et aI., 1997). In practice, however, with very few exceptions, the agroindustrial systems have proved to be strongly degrading. They are major factors in the non-potability of surface and ground waters, eutrophication ofcoastal ecosystems, increases in greenhouse gases, loss of biodiversity (Matson et al., 1997; Vitousek et al., 1997) and degradation ofthe productive capacity ofland by erosion, salinization, compaction and loss oforganic matter (Lal, 1997). In turn, enviromnental degradation has led to greater disparities in wealth and social well-being both between and within nations (Vosti and Reardon