|Resource Management for Upland Areas in Southeast Asia - An Information Kit (IIRR, 1995, 207 p.)|
|2. Integrated upland systems management|
Agroforestry has long been practiced by farmers in Thailand. Shifting (rotational) cultivation, for example, has been used by some ethnic groups in the upland areas of northern Thailand for centuries. In the Lab Lae district of Uttaradit province, homegardens have been cultivated for more than 200 years. Similarly, multistorey fruit orchards have been cultivated in many parts of the country for more than 100 years.
Traditional agroforestry, characterized by a simultaneous combination of trees and crops, low-input techniques and indigenous knowledge, are harmonized with local culture and traditions.
Newly developed agroforestry systems, with a systematic combination of trees, crops and livestock and usually driven by market forces, emerged in areas where cultivated land is limited, beginning during the mid-1950s. These systems were first introduced in Prae province, where teak plantations were intercropped with upland rice (in a taungya system). They have since evolved, however, into improved taungya systems, with crops, fruit trees and rubber trees grown in various combinations with timber trees.
Thailand's a total land area of 51,311,500 hectares, consists of 76 provinces with a population of 56.5 million and an average population density of 1.1 person per hectare. In 1988, 48.9 percent of the country was officially categorized as forest land, consisting of 1,215 national reserved forest areas 120 million hectares), 58 national parks (2.5 million hectares) and 30 wildlife sanctuaries (2.2 million hectares).
Homegardens are multitiered systems found in family compounds surrounding the home. Permanently settled communities in upland areas throughout the country have cultivated homegardens for centuries. Most notable are the Karen and the Lua ethnic groups. In the north, homegardens are mostly located in communities in the foothills. Owing to small landholdings in the central region of the country, homegardens here tend to be small.
Most homegardens have three to five layers. Erythrina dadap and banana are common tree species providing shade for crops and vegetables. Moringa oleifera and Sesbania grandiflora are commonly planted as multipurpose trees. In the south, big trees such as wild durian (Durio spp.), yang trees (Dipterocarp spp. ), Parkia speciosa and Artocarpus integer dominate the top storey of the gardens. Eugenia caryophyllus is commonly mixed with fruit trees to provide cash income.
Homegardens require considerable indigenous knowledge and labor to establish and maintain.
Live fences on farm land
Live fences of bamboo and fast-growing trees are common in the central and eastern regions of Thailand (Prachinburi, Nakornnayok, Srakhew and Chanthaburi provinces) where they serve as windbreaks and shelterbelts for crops and fruit orchards and as boundary markers. Commonly planted species are Thysostrycus siamensis, Bambusa nana, Bambusa flexuosa and Acacia spp. In the south, Azadiractha excelsa is commonly planted in and around farm fields.
Trees supply poles and wood for farms.
Fences protect crops in the field and reduce wind damage.
Some productive land must be sacrificed to establish the windbreaks.
Natural trees and shrubs left on agricultural land
Diverse trees and shrubs are deliberately left on farmland to serve as shade and provide green manure for crops such as rice and beans. The trees and shrubs also recycle minerals in the soil and control the development of problem soils, particularly saline soils in the northeastern region.
Small-scale block planting on abandoned agricultural land
Due to migration of rural people to cities, large marginal upland areas which used to be cultivated are being abandoned. This has presented an opportunity for small-scale commercial tree farming.
People from urban centers are investing in land in rural areas and planting high-value trees such as teak (Tectona grandis), eucalyptus and Azadirachta excelsa These species are longterm alternatives to large plantations for both economic and ecological reasons.
Shifting (rotational) cultivation
This system involves the cultivation of several areas of sloping land on a rotational basis (short cultivation, long fallow). It has long been sustainably practiced in upland and highland areas by several ethnic groups, most notably the Karen and the Lua. Rice and various other crops are planted simultaneously to produce food and fodder.
This system helps conserve the biodiversity of indigenous plant genetic resources such as rice, other crops and medicinal plants.
This system is rather fragile. It may collapse due to inappropriate interventions and population increases.
The system requires several pieces of land for adequate rotation and to allow the land to recover, thus it is inappropriate where land is scarce or population density is high.
Forest gardens include various indigenous forest and fruit trees, located away from but within walking distance of the family house. In forest gardens in central Thailand (Khao Sol Doa, Chanthaburi), Amomum xantitioides has been cultivated under moist evergreen forest for centuries. However, forest gardens are mostly found in the mountainous area of Uttaradit province in the north and Nakornsrithammarat, Trang and Phattalung provinces in the south.
In the northern forest gardens, Cammellia sinensis is cultivated under evergreen forests without having to cut trees in the forest.
In the south, wild durian (Durio sp.), duriannok (Durio sp.) takiens and yangs (Dipterocarp spp.) are the most dominant species of the top storey.
In the forest garden systems, trees and crops are simultaneously cultivated, thus requiring few inputs.
Because of their diversity, forest gardens are ecologically sound.
Because they are located away from the village, forest gardens are difficult to manage and are subject to loss from theft, fire, or livestock.
Forest plantation and livestock
This system incorporates cattle grazing under tree plantations. It is commonly practiced in old plantations where grasslands for livestock are scarce.
Forest species planted in this system are Tectona grandis, Dipterocarpus spp., Hevea brasiliensis and other fast-growing species, such as Eucalyptus spp. and Azadirachta indica.
This system reduces dry matter in the forest plantation, thus reducing the risk of fires.
Fruit trees, crops and other plants cannot be cultivated.
Without appropriate management of livestock numbers, season of grazing, etc., the soil can be seriously compacted by livestock.
This system, combining trees and livestock, was first developed under the government reforestation program, with an aim toward establishing teak plantations. It has since been expanded to include other species and to increase crop production. It is currently being practiced in both government and private forest plantations.
Forest tree species commonly planted include Tectona grandis, Pinus kesiya and Pterocarpus marcrocarpus. However, in some areas, fruit and rubber are also planted as the major trees. Normally, cash crops are intercropped with the trees in the early years of establishment. Livestock are usually allowed to graze in the plantation when the trees are more than three years old.
This system benefits the government and private companies by expanding forest plantations. It can benefit local people by providing land for fruit trees, crop and livestock production on a temporary or long-term basis.
Taungya systems have traditionally not been beneficial to local people over the long term. From the perspective of timber production, risks also exist that people will damage the trees in order to continue crop and fruit tree production and grazing beyond the limited number of years permitted by the system regulations.