According to the EU's AGFORWARD project, agroforestry can be defined as "the deliberate integration of woody vegetation (trees and/or shrubs) as an upper storey on land, with pasture (consumed by animals) or an agricultural crop in the lower storey. The woody species can be evenly or unevenly distributed or occur on the border of plots. The woody species can deliver forestry or agricultural products or other ecosystem services (i.e. provisioning, regulating or cultural)".
Agroforestry can take place at a range of scales (e.g. plot, farm and landscape). At farm and landscape scale it can be implemented in systems that are able to diversify production (e.g. food, forage, timber and fuelwood), provide ecosystem services (e.g. soil restoration, water preservation, climate regulation, and biodiversity enhancement), thus increasing both resilience and profitability.
Mosquera-Losada et al. (2016) describe five main types of agroforestry system. The two traditional descriptions of agroforestry in the temperate zone are as silvopastoral and silvoarable (respectively combining woody with forage and animal production, and widely spaced woody vegetation intercropped with annual or perennial crops). Silvopastoral systems can comprise forest or woodland grazing and pastoral land with hedgerows, copses, isolated/scattered trees or trees in hedges or belts. Silvoarable systems contain trees or shrubs that can be distributed in alley cropping, copses, as isolated/scattered trees or in hedges or belts. The other three agroforestry systems are a) hedgerows, windbreaks and riparian buffer strips b) forest farming c) home gardens or kitchen gardens. Home gardens tend not to be important in the temperate zone.
There can be some overlap between the five systems, as hedgerows, windbreaks and riparian buffer strips can be combined with arable land (silvoarable) or grasslands (silvopastoral). Other systems can be less easy to define; growing trees for timber or fruit with a bioenergy crop such as miscanthus is obviously silvoarable agroforestry, but growing timber trees with short rotation coppice willow for bioenergy is lease easy to classify.