Agroecological restoration

Agroecological restoration is the practice of re-integrating natural systems into agriculture in order to maximize sustainability, ecosystem services, and biodiversity. This is one example of a way to apply the principles of agroecology to an agricultural system.

Overview

Farms cannot be restored to a purely natural state because of the negative economic impact on farmers, but returning processes, such as pest control to nature with the method of intercropping, allows a farm to be more ecologically sustainable and, at the same time, economically viable. Agroecological restoration works toward this balance of sustainability and economic viability because conventional farming is not sustainable over the long run without the integration of natural systems and because the use of land for agriculture has been a driving force in creating the present world biodiversity crisis. Its efforts are complementary to, rather than a substitute for, biological conservation.[1]

"...biodiversity is just as important on farms and in fields as it is in deep river valleys or mountain cloud forests."

FAO, 15 October 2004

Agriculture creates a conflict over the use of land between wildlife and humans. Though the domestication of crop plants occurred 10,000 years ago, a 500% increase in the amount of pasture and crop land over the last three hundred years has led to the rapid loss of natural habitats.[2] In recent years, the world community acknowledged the value of biodiversity in treaties, such as the 1992 landmark Convention on Biological Diversity.[3]

Reintegration

The reintegration of agricultural systems into more natural systems will result in decreased yield and produce a more complex system, but there will be considerable gains in biodiversity and ecosystem services.

Biodiversity

The Food and Agriculture Organization of the United Nations estimates that more than 40% of earth’s land surface is currently used for agriculture. And because so much land has been converted to agriculture, habitat loss is recognized as the driving force in biodiversity loss (FAO). This biodiversity loss often occurred in two steps, as in the American Midwest, with the introduction of mixed farming carried out on small farms and then with the widespread use of mechanized farming and monoculture beginning after World War II.[4] The decline in farmland biodiversity can now be traced to changes in farming practices and increased agricultural intensity.[5]

Increasing heterogeneity

Heterogeneity (here, the diversity or complexity of the landscape) has been shown to be associated with species diversity. For example, the abundance of butterflies has been found to increase with heterogeneity. One important part of maintaining heterogeneity in the spaces between different fields is made up of habitat that is not cropped, such as grass margins and strips, scrub along field boundaries, woodland, ponds, and fallow land. These seemingly unimportant pieces of land are crucial for the biodiversity of a farm. The presence of field margins benefits many different taxa: the plants attract herbivorous insects, will which attract certain species of birds and those birds will attract their natural predators. Also, the cover provided by the no cropped habitat allows the species that need a large range to move across the landscape.[6]

Monoculture

In the absence of cover, species face a landscape in which their habitat is greatly fragmented. The isolation of a species to a small habitat that it can’t safely wander from can create a genetic bottleneck, decreasing the resilience of the particular population, and be another factor leading to the decline of the total population of the species.[7] Monoculture, the practice of producing a single crop over a wide area, causes fragmentation. In conventional farming, monoculture, such as with rotations of corn and soybean crops planted in alternating growing seasons, is used so that very high yields can be produced. After the mechanization of farming, monoculture became a standard practice in corn-beans rotation, and had broad implications for the long-term sustainability and biodiversity of farms. Whereas organic fertilizers, had kept the soil’s nutrients fixed to the ecosystem, the introduction of monoculture removed the nutrients and farmers compensated for that loss by using inorganic fertilizers. It is estimated that humans have doubled the rate of nitrogen input into the nitrogen cycle, mostly since 1975. As a result, the biological processes that controlled the way crops used the nutrients changed and the leached nitrogen from farmland soils has become a source of pollution.[8]

Organic farming

Organic farming is defined in different legal terms by different nations, but its main distinction from conventional farming is that it prohibits the use of synthetic chemicals in crop and livestock production. Often, it also includes diverse crop rotations and provides non-cropped habitat for insects that provide ecosystem services, such as pest control and pollination.[9] However, it is merely encouraged that organic farmers follow those kinds of wildlife friendly practices, and as a result there is a great difference between the ecosystem services that similarly sized but distinctly managed organic farms provide.[10] A recent review of the 76 studies concerning the relationship between biodiversity and organic farming listed three practices associated with organic farming that accounted for the higher biodiversity counts found in organic farms as compared to conventional farms.

"1. Prohibition/reduced use of chemical pesticides and inorganic fertilizers is likely to have a positive impact through the removal of both direct and indirect negative effects on arable plants, invertebrates and vertebrates.
2. Sympathetic management of non-crop habitats and field margins can enhance diversity and abundance of arable plants, invertebrates, birds and mammals.
3. Preservation of mixed farming is likely to positively impact farmland biodiversity through the provision of greater habitat heterogeneity at a variety of temporal and spacial scales within the landscape.[11]"

Notes

  1. ↑ 1.^ Jackson et al., The Farm as Natural Habitat, Introduction
  2. ↑ ^ Macdonald, Key Topics in Conservation Biology, Chapter 16
  3. ↑ 3.^ http://www.fao.org/newsroom/en/focus/2004/51102/index.html
  4. ↑ 4. Jackson et al., The Farm as Natural Habitat, Ch. 10
  5. ↑ 5.^ Benton et al., 182
  6. ↑ 6.^ Benton et al., 183–184
  7. ↑ 7.^ Macdonald et al., Key Topics in Conservation Biology, Ch 4
  8. ↑ 8. Jackson et al., The Farm as Natural Habitat, Ch. 10
  9. ↑ 9.^ Zhang et al., 255
  10. ↑ 10.^ Hole D.G. et al., 114
  11. ↑ 11.^ Hole D.G. et al., 120

References