Biodiversity and agriculture

The structure and function of agriculture ecosystem is largely supported by an array of biological diversity. Biodiversity is the basis of agriculture and our food systems. It has enabled farming systems to evolve since the origin of agriculture about 10,000 years ago. is not just a subset of biodiversity but represents an extension of it so as to embrace units (such as cultivars, pure lines, breeds and strains) and habitats (agro-ecosystems such as farmers’ fields and fisheries) that are not normally considered or even accepted by some conservation biologists as properly part of biological diversity. It includes all those species (including crop wild relatives) and the crop varieties, animal breeds, races and microorganism strains that are used directly or indirectly for food and agriculture, both as human nutrition and as feed (including grazing) for domesticated and semi-domesticated animals and the range of environments in which agriculture is practiced. Agricultural biodiversity also includes habitats and species outside of farming systems that benefit agriculture and enhance ecosystem functions (Heywood, 2003; Heywood, 2013). Agricultural biodiversity is the result of both human and natural selection. Domesticated crops and animals result from human management of biological diversity and their continuous evolution through improvement by breeders and farmers constantly responds to new challenges to maintain and increase productivity. In crop agriculture, for some species this selection has led to the development of manythousands of ‘landraces’ or ‘farmers’ varieties’ (Cromwell, 1999). Agricultural biodiversity provides humans with food, raw materials for goods such as: cotton and wool for clothing, wood for shelter and fuel, plants and roots for medicines and materials for biofuels. According to the FAO, about 7,000 species of plants have been cultivated since humans first began farming. However, today only 30 crops provide an estimated 90% of the world’s population dietary energy requirements, with wheat, rice and maize alone providing about half the dietary energy consumed globally. Of the estimated 15,000 species of mammals and birds, only some 30 to 40 have been domesticated for food production and less than 14 species, including cattle, goats, sheep, buffalo and chickens account for 90% of global livestock production (www.cbd.int). Agricultural biodiversity also performs ecosystem services such as soil and water conservation, maintenance of soil fertility, conservation of biota and pollination of plants, all of which are essential for food production and for human survival.  In addition to that, genetic diversity of agricultural biodiversity provides species with the ability to adapt for changing environments and to evolve by increasing their adaptation to frost, high temperature, drought and submergence as well as their resistances to diseases, insects and parasites (www.worldfoodprize.org). Besides the direct function in agriculture, biodiversity also provides other values indirectly. Due to the presence of hedges, ditches, field margins, hedgerows, etc. the cultural aspects of landscape design are preserved, but these elements also form the specific habitat for insects, birds, plants and other animals. Thus biodiversity has a high cultural and natural value, but can also support agricultural production e.g. nutrition, animal health (as leaves of shrubs and trees contain health-promoting substances) and welfare of livestock (animal behavior and shade), or the provisioning of insects for pollination or biological plague reduction. When aiming for a durable and robust farming system and thus for sustainable agriculture, it is essential to preserve, support, use and promote biodiversity (Erisman, 2016).

This is certainly true and often argued that agricultural biodiversity as such is an important asset that delivers substantial benefits in many different realms and that there is increasing evidence that biological diversity needs to be a central element of sustainable agricultural development. Higher diversity is actually more effective in increasing productivity than higher management intensity. It was found that wheat production increased 74% when intercropped with maize and a 53% increase observed when intercropped with soybean. Chickpea improves Phosphorous uptake by wheat and maize via a complex pathway that pits the cereals greater ability to absorb soluble P against the legume’s greater ability to mobilize organic Phosphorous. Intercropping reduces the accumulation of nitrate in the soil, permitting lower application rates of N and reducing downstream effects (Mundt 2002; Li et al., 2004; Frisonet al., 2011).

However, agricultural practice has been defamed to be thelargest driver of a complex system which leads to major loss of biodiversity. Some of the prominent reasons are conversion of natural ecosystems into farms andranches, intensification of management in long-established cultural landscapes, release of pollutants, including greenhouse gases  and associated value chain impacts, including energyand transport use and food waste(Dudley and Alexander, 2017). At the same time, it should be realized that solutions based on the use of components of biological diversity are at the heart of agro-ecological practices, which intensify production while reducing pressures on the environment. Use of biodiversity-based approaches on the vast area of land can reduce emissions and runoff, decrease the need for synthetic inputs, improve soil quality, encourage pollinators and conserve varieties and species.  (https://www.bioversityinternational.org). Diverse range of organisms contributes to theresilience of agricultural ecosystems to change climatic condition and their capacity to recoverfrom environmental stress (biotic and abiotic) and to evolve and improve genetically. Wide range of biological diversity in and near agricultural ecosystems is essential to sustain many of its functions such as nutrient cycling, decomposition of organic matter, crustedor degraded soil rehabilitation, pest and disease regulation, pesticide and fertilizer degradation, pollination, etc. (www.fao.org/biodiversity). Diversified agricultural production and polycultural systems also offer opportunities to expand new markets and further stimulate the conservation of biodiversity important to agriculture. Sustainable use of agricultural biodiversity can provide benefits to environment, economy, society and culture on national, regional and global scales (Scherr and McNeely, 2007).

The above discussions clearly depicted that healthy and diverse flora, fauna and microorganisms are very much essential for a sustainable agricultural production system. In the forthcoming sections, specific discussionshave been carried out on the various beneficial roles and applications of each group of organisms on various components of agricultural ecosystem.