The 880 mm of rainfall that the landscape around Jhansi (India) receives in an average year easily allows for one cropping season. In the long dry season, however, life becomes difficult in the rural areas and the wells used for irrigating a second crop rapidly dry up, so only a small part of the land can be cropped twice. Many people look for seasonal jobs in cities in this period, as even drinking water becomes hard to obtain, while the livestock roams around freely to feed on whatever biomass it can find. This practice of abandoning cattle is known as annapratha locally.

For over a decade, the Chinese government has implemented the Sloping Land Conversion Programme (SLCP), the world’s largest payments for ecosystem services (PES) programme. It uses public payments to convert marginal cropland located in upper watersheds into forests, engaging millions of mountain-dwelling households in the process. The SLCP has received significant criticism from researchers in China and abroad in term of its effectiveness, efficiency and fairness.

Setting the scene: a 40,000 ha area, home to 100,000 people, with coffee (robusta) production as primary source of income, living in a huge old crater, with consequences for spatial variability of soil properties from various eruptions and lava flows. Adjacent to the Bukit Barisan mountain range that runs along the length of Sumatra island (Indonesia), the Way Besai river feeds one of Lampung’s main rivers. Coffee farming expanded here from start of 20’th century, but a large influx from Java (government sponsored + spontaneous migrants) led to a densely populated landscape.

There is little doubt that a remarkable ‘regreening’ has taken place in part of the Sahel in recent decades. After severe episodes of drought and famine in the 1970s and 80s, that caused massive crop and livestock losses, and human migration and mortality, a process of agroforestation on more than 5 million hectares of farmlands has ‘regreened’ the southern part of Niger.

There are many ways to classify and describe agroforestry practices based on the spatial and temporal arrangement of trees, the type of trees in relation to economic value, the non-tree components (crops, livestock, fish) or the balance between retained, spontaneous and planted trees (compare with Chapter 2). The simplest way that is compatible with existing global data sets may well be the classification of tree canopy cover on agricultural land because it allows a direct comparison across regions and countries.

Cropping systems based on carefully designed species’ mixtures over time (in terms of crop sequences) and/or space (within a farm or landscape) reveal many potential advantages under various conditions, both in temperate and tropical agriculture. In general, annual crops are expected to be relatively shallow-rooted while perennial plants, including trees, can have roots extending deep below the crop root zone, giving a foundation to the safety-net hypothesis5.

World Agroforestry (ICRAF) has as its mandate all agricultural land use that involves trees, beyond what is considered to be forest. The latter distinction is rather fluid, both temporally and institutionally, as the example of long-rotation shifting cultivation may show. Agroforestry itself ranges from croplands with a few trees added through to systems where tree crops (considered to be agricultural, such as coffee, cacao or rubber) provide a perennial vegetation layer, augmented with upper canopy layer trees utilized to modify microclimate, yielding economically valuable products.

The domestication of trees is essential to enhance the products and services provided by agroforestry systems1. A range of domestication methods has been developed over recent decades. These methods are context specific and include a participatory domestication approach involving scientists and farmers working in close collaboration. This approach has had positive impacts on incomes, diets and in rural business development.

Trees and forest relate to each other like eggs and chicken, and it is not possible to say which came first. Trees wouldn’t grow as tall as they do without forest neighbours, and forests without trees exist only on paper and in a policy sense. From an agricultural perspective the trees are the most distinctive aspect of agroforestry, and similarity with forests is a secondary concept, however (Box 2.1).