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Increase in biodiversity and stability of agroecosystems

Increase in biodiversity and stability of agroecosystems

Nature increases its complexity and reciprocity to improve its energy efficiency in space and time (photosynthesis, exchange of metabolites, primary productivity, etc.). This assumption is confirmed by the many works addressed, between the second half of the last century and the beginning of this one, with the study of dissipative structures (which are also ecosystems) by various authors (Prigogine I., Nicolis G. 1982, Zhang H., Wu J. 2002).
The increase in the diversity of agricultural, forestry and livestock systems, in addition to giving greater stability to agroecosystems, positively influences social ecosystems. An increase in associated information is also linked to the increase in biodiversity. In this condition the agri-food system ensures a more balanced and varied dietary and nutritional relationship and therefore better requirements for safeguarding the health of consumers.
Among other things, the good quality of the food we eat is essential not only for maintaining a state of health, but equally indispensable for respecting the land and good production practices. A two-way relationship that requires careful and aware agriculture which at the same time can play an important role in protecting and enhancing the environment, biodiversity, the territory and its livability (Schiavone F. 2018).
Furthermore, plant diversity potentially provides a partial or complete substitute for many expensive agricultural inputs, such as fertilizers, pesticides, imported pollinators, and irrigation.
In the future, the benefits of diversifying agroecosystems are expected to be greatest where the goal is to sustainably intensify production while reducing conventional inputs or to optimize both yields and ecosystem services. In the coming decades, as monoculture yields continue to decelerate or decline for many crops, and as demand for ecosystem services continues to increase, diversification could become an essential tool for sustaining production and ecosystem services on croplands, rangelands and in productive forests (Isbell F. et al. 2017).
Agricultural systems with greater biodiversity and, above all, with cultivation or breeding of native species and breeds therefore present greater stability and resilience, especially in a period characterized by rapid climate change.
Unfortunately, the spread of monoculture has led to the abandonment of traditional agricultural practices; thus a large number of varieties of plants and animal breeds have silently disappeared, causing a silent extinction of agricultural biodiversity which, in some conditions, becomes irreversible at least in the short term.
The reconversion of ancient cultivation techniques towards the classic monoculture fields of intensive agriculture has also required an ever-increasing supply of external inputs (fertilizers, insecticides, fungicides, water, etc.); factors that have contributed to the erosion of natural biodiversity (insects, mammals, plant species, etc.).
Furthermore, as ISPRA reports on its official website, on a global scale, the main factor in the loss of animal and plant biodiversity is linked to the destruction, degradation and fragmentation of habitats, in turn caused both by natural disasters (for example: fires, eruptions volcanoes, tsunamis, floods, etc.) and above all by profound changes to the territory caused by man. Thus many forests and wild areas have been destroyed to take plants or parts of plants for the pharmaceutical or cosmetic industry; Even in the richest and most industrialized countries, the loss of biodiversity continues due to the destruction of natural or semi-natural habitats, to build airports, shopping centres, car parks and homes. The countryside, the forest, the wetland, the prairie pay the price. According to the FAO, over the last ten years an average of 13 million hectares of forests have been destroyed per year (an area equal to that of Greece). Furthermore, other millions of hectares are degraded every year by the harvesting of timber, the construction of mines, dams, roads, etc.
The gradual transformation of agroecosystems has generated extremely simple and homogeneous production systems (often with a single variety cultivated over very large surfaces); in these conditions there is less and less space for agricultural biodiversity and this context has become a factor in the alteration of all biotic relationships with other organisms which, consequently, interfere with normal population and distribution relationships. This condition is visible above all in the high infestations of insects, fungi, unwanted herbs which require further interventions by farmers with a vicious circle that is impossible to resolve.
This ecological error has thus determined the growing pollution of agroecosystems, the loss of fertility, the decrease in energy yields and, finally, the impoverishment of entire ecological and social areas, also due to the exodus of farmers from the countryside or small towns inhabited.
This evidence, increasingly clear, especially in recent times, has led many farmers and the world of research to identify alternative production models, based on agroecology, which are becoming established in various parts of the world.
All this is leading to the rediscovery of agricultural systems tending to recover and improve not only ancient peasant traditions but also to a review of research and the technical and practical implications of the role of biodiversity in agroecosystems.
Agroecology, therefore, sets itself the objective of gradually reconverting the agricultural systems which, in much of the planet, were born with the so-called green revolution, a process which, in many cases, was in clear contrast to the so-called traditional agriculture , which had characterized our history until the beginning of the twentieth century and beyond. To do this, the contribution of a new class of farmers who pay attention to the biodiversity of their territories, rediscovering and revaluing it (Macellari E. 2021) is essential.
In fact, we must remember that farmers played a key role in the creation of agricultural biodiversity by domesticating crops and spreading them over increasingly larger areas, taking them with them on migrations. This dispersion from the centers of origin, linked to human activity, has played the major role in diversifying seeds, making them more adaptable to different ecological and environmental conditions.
Wherever plants have been taken, they have been modified by the environment and by the cultivation methods adopted by different civilisations.
The gradual and painstaking work of selection of the natural and cultural environment has resulted in the establishment of local varieties (landraces), a term that underlines their distinction from modern varieties.
In fact, the former are the result of a localized adaptation process and are therefore extremely diversified from each other; the modern ones have instead been selected to be able to use the same variety in different environments, frequently requiring intensive agricultural techniques, and often presenting themselves with a strong genetic homogeneity.
Unfortunately, the decrease in seed and breed varieties has been accompanied by a gradual loss of related knowledge. The farmers, who had historically cultivated certain varieties or breeds, were aware of the complex factors that affected their biological cycles, having thus also acquired the knowledge for most of the adversities that arose from time to time.
With the disappearance of these varieties and breeds, modern farmers found themselves managing genetic material and techniques that were not the result of knowledge, often accumulated over the centuries, and with the need to resort to a series of external inputs, increasing, among the costs of the production processes and losing, at the same time, the particular knowledge useful for managing ordinary or extraordinary conditions.
Agricultural, livestock and forestry systems, and their synergies, must therefore start again from a careful redesign of their dynamics, involving within them criteria for increasing their biodiversity, both in space and time (intercrops and rotations), and relating the increase in the diversity of agro-forestry-pastoral production to a new market system, much more integrated with local populations (food sovereignty) and with nutritional needs of a higher qualitative and organoleptic level.
Biodiversity in agroecosystems offers numerous benefits. For example, greater crop diversity promotes resistance to disease and pest infestations, thus reducing the need for pesticides and improving plant health. At the same time, the presence of pollinating insects and natural predators helps to control the populations of phytophagous insects and improve the quality of the crop.
Furthermore, greater plant biodiversity promotes soil conservation, reducing erosion and improving its fertility. The roots of different plants can penetrate different depths into the soil, promoting soil structure and nutrient recycling. The presence of soil organisms such as bacteria, fungi and earthworms is also essential for soil health and the decomposition of organic matter.
Biodiversity in agroecosystems can be promoted through various sustainable agricultural practices. Some examples include crop rotation, precision agriculture, the use of cover crops and the conservation of natural habitats in agricultural areas. Furthermore, the adoption of agroecological methods, which reduce the use of synthetic chemicals and promote integrated resource management, promotes biological diversity and the stability of agroecosystems.
It is important to underline that promoting biodiversity in agroecosystems not only brings significant benefits to the environment, but helps create economic benefits for farmers. For example, a greater diversity of crops can lead to greater income, thanks to the sale of diversified products and the reduction of costs associated with the use of pesticides and fertilizers and, in any case, external inputs.
In conclusion, increasing biodiversity is crucial to guarantee the stability of agroecosystems. Promoting plant and animal diversity, through sustainable agricultural practices, improves the resilience of agroecosystems to environmental disturbances and contributes to long-term sustainable food production.

Guido Bissanti

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