| Resource management for upland areas in Southeast Asia - An information kit |
|2. Integrated upland systems management|
Agroforestry has been traditionally practiced by different tribal groups in the Philippines for generations. This land-use system is now recognized by the government as one of the alternatives to address the twin problems of meeting the needs of upland farmers and maintaining the integrity of the environment. It is one of the major components of the community-based forestry programs of the government, such as the Integrated Social Forestry Program and the Community Forestry Program. Many nongovernment organizations also develop and promote different forms of agroforestry as approaches for sustainable upland development.
Farm-based agroforestry systems
Alley cropping is also known as hedgerow intercropping system. Hedgerows of trees or shrubs (usually double hedgerows) are grown at intervals (usually 4-6 m) along the contours. The strips or alleys between the hedgerows are planted with agricultural crops (annuals and/or perennials).
A good example of this system is the Sloping Agricultural Land Technology (SALT).
One or two rows of woody perennials are grown as hedgerows, either from seeds or cuttings, along the contours. Contour lines are located using an Aframe tool. The recommended horizontal distance between contour hedgerows is 46 m or about 1.5 m vertical distance. At an average of 5 m interval (horizontal distance) and l m width of hedgerows, about 20% of the total area is occupied by the hedgerows. For the alleys, the recommended cropping pattern is to plant perennial crops (e.g., coffee, fruit trees, etc.) in every third alley while the other two alleys can be devoted to annual crops. This makes a spatial ratio of about 20% hedgerows, 25% perennials and 55% annuals.
Philippine upland situation (1990)
· Uplands constitute 17.5 million ha, or 59% of the total land area.
· About 12.2 million ha are marginal upland areas.
0.30 million ha
1.80 million ha
Cultivated mixed grasslands
10.11 million ha
Eroded and other barren areas
0.01 million ha
12.22 million ha
· Upland population is estimated to be about 18 million, or more than 3 million households.
—8.5 million forest dwellers
—6.0 million tribal Filipinos
—3.3 million migrants from lowland areas
· At a population growth rate of 2.6% per year, an additional 5.25 million ha of forest lands will be cleared by the year 2025.
The hedgerows are regularly pruned to a height of about 0. 5 m to minimize shading of agricultural crops in the alleys. The pruning frequency depends on the coppicing ability of the species. Biomass from the prunings can be used as green manure or mulch to the alley crops or as fodder fed to livestock. Through time, natural terraces can form at the base of the hedgerows, thereby minimizing soil erosion and surface run-off.
· Conserves soil and water.
· Can increase crop yield and farm income (e.g., 4-5 fold increase in maize yield when compared to maize yield of upland fields without hedgerows.
· Flexible since different cropping systems can be integrated (e.g., annual and perennial crops can be mixed in different ratios along the alleys; livestock can also be integrated.)
· Reduces dependence on inorganic fertilizers. (Prunings can be used as organic fertilizer.)
· Can decrease overall farm yield due to: (1) loss of cropland resulting from hedgerow establishment; (2) improper pruning and too-close hedgerow interval can reduce light penetration, and (3) some hedgerows may have allelopathic properties which can adversely affect crop growth.
· Laborious to establish and maintain.
Alley cropping with improved pasture grasses and/or fodder trees or shrubs
Hedgerows of fodder trees or shrubs (e.g., Desmodium rensonii, Leucaena leucocephala, Gliricidia septum, Flemingia congesta) are planted along contours at intervals. The alleys between the hedgerows are planted with improved pasture grasses and/or fodder trees or shrubs. Pruning from the hedgerows grasses and fodder trees/shrubs are fed to animals in a cut-and-carry method.
Ideal characteristics of hedgerow species
· easy to establish (from seed or cutting)
· good coppicing ability
· deep-rooted has multiple uses (i.e., food, fuel, fodder, etc.)
Some recommended hedgerow species
· GliricidÃa septum
· Flemingia congesta
· Leucaena leucocephala
· Desmodium rensonni Cassia spectabilis Calliandra calothyrsus
· Desmanthus sp.
· Some grasses such as napier (Pennisetum purpureum), vetiver ( Vetiveria zizanoides), guinea grass (Panicum maximum) and Setaria sp.
In this agroforestry system, mixed species occupy different canopy levels, with the upper layers occupied by trees or other woody perennials that provide partial shade to agricultural crops in the lower layers. This system is similar to the structure (multilayer) and composition (diverse species) of a tropical rainforest. Examples are coconut-coffee-pineapple-banana mix (commonly found in Cavite province); Albizia-coffee/cacao mix (commonly found in provinces of Mindanao); Gliricidia-coffee mix (found in many areas); and homegardens (found throughout the country).
This system can be adapted by interplanting shade-tolerant species under established tree and coconut plantations.
· Promotes optimum utilization of light and soil resources.
· Promotes efficient nutrient cycling.
· Series of canopy layers minimizes rainfall impact, thus reducing soil erosion and runoff.
· Promotes greater diversity; hence, crops become less prone to pests and diseases.
· Diversified cropping helps to ensure a year-round source of food and income.
· Promotes maximum utilization of labor and time.
Possibility of too much competition among crops for light and nutrients.
Desirable characteristics of upper canopy trees
· small crown or sparse foliage to allow some light to pass through to lower canopies
Some common nursery trees for coffee and cacao plantations
· Gliricidia septum
· Alnus japonica
· Leucaena leucocephala
· Erythrina orientalis
· Paraseriantes falcataria
· Pterocarpus indicus
· Samanea saman
Multistorey system + animals
This system is similar to the multistorey system except that freerange grazing animals are added as a component. An example is the coconut-lanzones mixture, with horses or cattle, found in Laguna and Quezon provinces.
Trees along farm boundaries
Trees are planted along farm boundaries as: boundary marker, live fence, live-fence post for tying barbed wire or bamboo slats, or as shelterbelts/windbreaks.
When mature, some of these trees can be harvested and used as posts or as light construction materials. Pruning can also provide fuelwood, fodder or green manure.
Live fences (or living fences) can be established by planting rows of trees or shrubs around a grassland area to enclose the grazing animals. Aside from the tree's role as a fence, it can be managed (e.g., by regular top-pruning to encourage more lateral branching) so that the enclosed animals can browse on the low-lying branches, which serve as fodder supplement.
· Trees serve as windbreak or live fence.
· Trees serve as source of post, fuelwood, fodder, green manure and live trellis.
· Possible shading of crops by tree.
· Can be difficult to establish if animals are allowed to graze, as they may browse the trees before they are well-established as a fence
Species used as live fence
· Leucaena leucocephala
· Gliricidia septum
· Sesbania grandiflora
Species used as windbreak/shelterb elt
· Eucalyptus camaldulensis
· Casuarina equisettifolia
· Acacia auriculiformis
Trees as live trellis
Trees are top-pruned (pollarded) to serve as live trellis for climbing crops, especially vegetables like beans, peppers, yams and cucumbers. The most commonly used trees as live trellis are Gliricidia septum and Leucaena leucocephala.
Tree-crop grazing system
Animals (e.g., cattle, carabao, goats, sheep) are allowed to graze freely underneath relatively mature tree plantations. A good example is the silviculture scheme of the Nasipit Lumber Company in Agusan province.
The cattle are allowed to graze freely under lumbang (Aleurites moluccana) trees where improved forage grasses have been planted. This system has proven to be practical and economical because the land is fully utilized while being maintained and protected. The grazing animals keep the grass down, allowing for easier collection of the lumbang nuts.
Protein or fodder bank
Leguminous fodder trees or shrubs (e.g., Leucaena, Gliricidia, Flemingia) may be established in intensively planted small stands on the farm. These are usually fenced off and serve as a supplementary source of protein for livestock. The top and branch prunings are fed to animals through a "cutand-carry" system. A good example is the intensive feed garden.
· Ideal for coconut plantations commonly found throughout the Philippines
· Grazing animals may eat the tree bark if it is palatable.
Forest-based agroforestry systems
Taungya is an agroforestry system in which newly established reforestation areas are interplanted with agricultural crops. As soon as the tree canopies close making the light intensity critically low for crop production, the farmers move to another reforestation area and the same process is repeated. An example of this is the Family Approach to Reforestation piloted by the Bureau of Forest Development (now the Department of Environment and Natural Resources).
· Proven to be a cost-effective reforestation strategy.
· Farmers cannot grow permanent crops since they have to leave the area as soon as the tree canopies start to close (after 3-5 years).
· Can be discouraging to farmers as the more they care for the area (e.g., weeding and fertilizing their crops which also favor the trees), the faster the trees grow and the sooner they will lose access to the land.
· Provides only a temporary, supplementary source of food and income for the first 3-5 years after the establishment of the reforestation area.
· Family resettlement after the tree canopy closes can be very difficult.
Alley cropping—tree plantation integrated production system
In this system, the upper 60% of the hillside is devoted to small-scale tree plantation, devoting one or more forest tree species for various uses (e.g., timber, polewood and/or fuelwood). These tree plantations may be established at close spacing to ensure that poles and posts are produced. When the trees are already tall enough, rattan or other shadetolerant crops can be interplanted. The lower 40% of the hillside is devoted to food production where the alley cropping system is practiced.
· Effectively conserves soil.
· Provides abundant food, wood and income for upland farmers.
Improved fallow system
In the uplands, cultivated areas are planted with agricultural crops and then allowed to fallow for some time to allow the soil to rejuvenate. To shorten the fallow period, the area can be seeded with leguminous trees. Once the soil has been rejuvenated, these areas are again cleared for crops. This can be considered as an improved version of the traditional shifting cultivation practice.
An example is the Naalad-style farming system, practiced in Naalad, Naga, Cebu. In this system, the native Leucaena is used as the species to shorten the fallow period; the trees are cut and the branches are piled along the contours to form a barrier structure known locally as balabag, which traps the eroding soil. Through time, natural terraces are gradually formed, thus stabilizing the steep slopes.
(improved fallow system vs. traditional shifting cultivation)
· Introduction of nitrogen-fixing trees as fallow species shortens the fallow period required for soil rejuvenation.
· Terraces are gradually formed, thus stabilizing slopes.
· Promotes efficient nutrient cycling (no burn).
· Laborious because of the construction and maintenance of the balabag.
· Wood from the fallow species (Leucaena) is used for construction of the balabag rather than for fuel.
Rice terraces—forest agroforestry system
This indigenous agroforestry system can be considered sustainable as it has existed for more than 2000 years, as pioneered by the Ifugao tribe in northern Philippines. A series of bench terraces is constructed along steep mountainsides and rice is planted throughout the year. Irrigation is provided through a network of canals along dikes which originate from natural springs emanating from small forest stands celled pinugo. These are managed and protected by Ifugaos based on a set of tribal laws.
· Steep slopes are put to productive use.
· Laborious to establish and maintain.
· Limited to areas where there are natural springs.