Agroforestry: potentially more productive and sustainable cropping systems

The growing world population pressure, and the resulting need to increase agricultural food production, require a profound readaptation of the land use system models in order to combine environmental sustainability with higher yield and better use of agricultural and forestry resources. Agroforestry (AF) systems can effectively contribute to these goals, proposing mixed land use systems in which the combined management of woody perennials with herbaceous crops and/or livestock can increase out - puts through more efficient use of natural resources, while significantly improving environmental benefits. These objectives can be pursued through the development of new AF systems, able to adapt to the modern needs of industrial agriculture, as well through the protection and enhancement of the remaining traditional AF systems, important elements for conservation of biodiversity and cultural witness. Recent field research showed that AF systems can have values of Land Equivalent Ratio (LER) mostly comprised between 1.2 and 1.4, with very high production efficiency. For example, modern silvoarable systems, combining walnut for timber production intercropped with wheat, have a LER of 1.4, indicating that 100 ha of AF system produce as 140 ha of the two components in monoculture. Furthermore, modeling and experimental results have shown significant benefits in reducing soil erosion and Nitrogen leaching, and increasing soil C. Linear tree systems with woody plants along the edges of the fields are being re-evaluated according to their productive capacity (biomass for energy, timber) and phytoremediation capacity of soil and water bodies contaminated by agricultural pollutants. Temporary fast growing tree woodlots (as Short Rotation Coppice plantations) can be used for the decontamination of agricultural polluted soils through in situ techni - ques of biodegradation. Traditional silvo-pastoral systems, often with centuries of management history, such as the wooded pastures in the mountains and in Mediterranean areas, still represent a real alternative to modern intensive livestock farming systems. The additional forage resources from trees and shrubs reduce the need for external energy inputs for animal feeding, improving product quality and animal welfare, as well reducing or eliminating the massive production of animal wastes with dra - matic disposal problems. In many marginal areas, extended arboreal-shrub ecosystems are deeply related to grazing, with beneficial impacts on biodiversity and protection against forest fires. Economic simulations at the farm level, indicate that a partial conversion to agroforestry can bring significant economic benefits to the farmer, who must be still supported by a policy that recognizes the economic, environmental and social impacts of agroforestry. This recognition is still dramatically lacking. Enhanced cooperation between farmers is also crucial for the development of unexploited productive resources, such as timber trees, traditional fruit varieties, biomass for energy; these resources are very often scattered and fragmented in many agrofore - stry landscape mosaics that are common to many marginal rural areas. Research, knowledge and political support are three fundamental elements, necessary to implement agroforestry locally and globally, in order to respond to the challenge of modernization and sustainability.