Agroecology goes beyond a one-dimensional view of agroecosystems – their genetics, agronomy, edaphology, etc., – to embrace an understanding of ecological and social levels of co-evolution, structure and function. Instead of focusing on one particular component of the agroecosystem, agroecology emphasises the interrelatedness of all agroecosystem components and the complex dynamics of ecological processes that drive productivity, stability and resilience. Agroecology integrates natural and social processes joining political ecology, ecological economics and ethnoecology among the hybrid disciplines. Agroecology uses a systemic approach therefore it has long been considered a transdiscipline as it integrates the advances and methods of several other fields of knowledge around the concept of the agroecosystem viewed as a socioecological system.
Agroecology aims at the holistic study of agroecosystems which are seen as complex systems in which ecological processes occur, e.g. nutrient cycling, predator/prey interactions, competition, symbiosis and successional changes. Implicit in agroecological research is the idea that, by understanding these ecological relationships and processes, agroecosystems can be manipulated to improve production and to produce more sustainably, with fewer negative environmental or social impacts and fewer external inputs.
At the heart of the agroecology strategy is the idea that an agroecosystem should mimic the functioning of local ecosystems thus exhibiting tight nutrient cycling, complex structure, and enhanced biodiversity. The expectation is that such agricultural mimics, like their natural models, can be productive, pest resistant and conservative of nutrients.
A key agroecological strategy in designing a sustainable agriculture is to reincorporate diversity into the agricultural fields and surrounding landscapes. Diversification at the field level occurs as variety mixtures, rotations, polycultures, agroforestry, croplivestock integration, etc and at the landscape level in the form of hedgerows, corridors, etc, giving farmers a wide variety of options to assemble spatial and temporal combinations. Emergent ecological properties develop in diversified agroecosystems allowing the system to function in ways that maintain soil fertility, crop production, and pest regulation. Agroecological management practices that increase agroecosystem diversity and complexity act as the foundation for soil quality, plant health and crop productivity.
Biodiversity enhances agroecosystem function because different species or genotypes perform slightly different functions and therefore have different niches In diversified agroecosystems there are many more species than there are functions and thus redundancy is built into the agroecosystem. Those components that appear redundant at one point in time become important when some environmental change occurs. As environmental change occurs, the redundancies of the system allow for continued ecosystem functioning and provisioning of ecosystem services. On the other hand a diversity of species acts as a buffer against failure due to environmental fluctuations, by enhancing the compensation capacity of the agroecosystem. If one species fails, others can play their role, thus leading to more predictable aggregate community responses and maintenance of ecosystem properties.
Agroecological systems are deeply rooted in the ecological rationale of traditional small-scale farmers who for centuries have developed farming systems that offer promising sustainability models as these systems promote biodiversity, thrive without agrochemicals, and sustain year-round yields meeting local food needs. The evolution of these systems has been nourished by complex forms of traditional knowledge. Many farmers possess a detailed folk knowledge about vegetation, animals, soils, etc, within a certain geographical and cultural radius. Rural knowledge is based on observation and on experimental learning. Successful adaptations are passed from generation to generation and historically farmers have shared successful innovations with neighbors.
Small farming systems not only have fed much of the world population for centuries and continue to feed people in many parts of the planet, especially in developing countries, but also have the potential to bring solutions to many uncertainties facing humanity in a peak oil era of global climate change and financial crisis. Recent research has demonstrated that small diverse farms are more resilient to droughts and hurricanes. Undoubtedly, the ensemble of traditional crop management practices used by many resource-poor farmers represent a rich resource for agroecologists seeking to create novel agroecosystems well adapted to the local agroecological and socioeconomic circumstances of smallholders. Agroecologists recognize and value local wisdom and traditions, creating a dialogue with local actors via participatory research that leads to a constant creation of new knowledge.
A major goal of agroecology is the revitalization of peasant and small family farms and the reshaping of the entire agricultural policy and food system in ways that are economically viable and socially just to farmers and consumers. New approaches and technologies involving application of blended agroecological science and indigenous knowledge systems and spearheaded by thousands of farmers, NGOs, and some government and academic institutions are proving to enhance food security while conserving agrobiodiversity soil and water resources conservation throughout hundreds of rural communities in the developing world.