Agroforestry option

Opportunities

Production of livestock feed/fodder

Trees and shrubs (particularly leguminous species) may contribute to filling in the lack of nitrogen and protein in dry areas, supplying green fodder during the dry season. Trees and shrubs may be scattered in grazing land or be planted in "fodder banks" (fodder production during the dry season, "cut and carry"). Potential problem: lower palatability and digestibility due to tannins and other compounds.

Fruit production

Combining cropping and fruit production is traditional in the dry areas of CWANA; it is particularly attractive for areas where (supplemental) irrigation is possible. Nondemanding species such as Ziziphus, Annona and mango in the semiarid tropics, or olives, pomegranate and pistachios in the dry subtropics are intercropped with vegetables or cereals. Plastic tunnels and modern (drip) irrigation systems may render such systems quite productive and water efficient.

Wood production

Wood is used for fuel, construction, tools, art, fencing, etc. Production of firewood may substitute for livestock manure, which can thus be used to enhance and maintain soil fertility. Village woodlots are one approach.

Production of other goods

Trees can produce nontimber products such as traditional and modern medicines, gum arabic, fiber, dyes, cosmetics, oils, pesticides, silk (silkworm rearing). Diversifying production reduces risk and generates incomes, contributing to reducing poverty and improving livelihoods (Leakey et al., 2005).

Use of otherwise not usable water resources

Low-quality water may be used to increase productivity of agroforestry systems. Treated sewage effluent that cannot be used to produce food crops may still be suited to produce woody species, as certain trees and shrubs tolerate higher salt content than herbaceous plants (apply increasingly saline water to successively more salt-tolerant plants, Jorgensen et al., 1993).

Biodrainage

Deep roots of trees and shrubs may achieve good groundwater control, particularly at a local scale (see, e.g., Schofield et al., 1989 or Raper, 1998). This can considerably reduce the threat of salinization when groundwater tables come too close to the soil surface.

Soil fertility enhancement

Trees and shrubs may provide valuable additions to the soil by maintaining or increasing organic matter, by biological nitrogen fixation, through more efficient nutrient uptake (association vesicular arbuscular mycorrhiza) or by enhancing atmospheric nutrient input (dust and wet deposition). Trees may reduce loss of nutrients and organic matter, protecting the land against wind and water erosion by covering the soil surface with litter, reducing raindrop energy and wind velocity, providing physical barriers and protecting streambanks, or by retrieving nutrients from deep soil horizons.

Protection of soils against degradation, reclamation of degraded land

Protection measures using trees and shrubs include constructing contour vegetation strips, enforcing structural conservation measures such as stone bunds or terraces, protecting waterways, and stabilizing erosion gullies and sand dunes (Rocheleau et al., 1988; Baumer, 1990). Tree and shrub plantations on marginal lands prone to degradation may protect these resources from being cropped.

Protection of water resources

Contour buffer strips (reducing erosion, increasing sediment deposition, and facilitating water conveyance), riparian forest buffers (to reduce runoff and nonpoint source pollution from agricultural activities), and filter strips (vegetation for removing sediment, organic matter, and other pollutants from runoff and waste water) help in protecting water resources from pollution; use of excess and wastewater by trees; streambank protection; floodplain management ("waterbreaks").

Living hedges and fences

Protection of crops from freely roaming livestock through hedges and fences of indigenous thorny multipurpose trees and shrubs; use of large stem cuttings (e.g., of Gliricidia sepium) that quickly root and produce additional benefits (such as forage, green manure, or fruit) for fencing.

Reduced wind velocity (windbreaks)

Reduced wind velocity raises the relative humidity in the microclimate, which may reduce evapotranspiration. Windbreaks lessen wind erosion and sand shear, reduce loss of flowers in crops and deposition of dust (and thus nutrients) and snow (particularly important in the dry areas of Central Asia). The trees produce fuelwood, poles, fruit, fodder, mulch, etc. Potential problem: competition with crops for water and nutrients (Smith et al., 1997).

Provision of shade

Shade reduces energy expenditure of livestock for thermoregulation (cooling) in hot environments and thus increases productivity. It alters the microclimate and provides shelter.

Protection and conservation of biodiversity and wildlife

Trees provide a habitat for numerous forms of life and thus help in protecting and conserving biodiversity and wildlife. Trees on marginal lands may protect these areas from degradation, thereby helping conserve biodiversity.

Carbon sequestration

The introduction of agroforestry systems, together with grazing land management, is seen to represent a major opportunity to increase carbon sequestration in agriculture (IPCC, 2000).

Landscaping and beauty

Woody perennials may be used to order the landscape, by breaking monotony, furnishing landmarks (Baumer, 1990).