| Thai Highlands | |
|---|---|
| Map of the Thai highlands | |
| Thailand | Northern Thailand, parts of Tak and Sukhothai provinces |
| Area | |
| • Land | 107,000 km2 (41,312.9 sq mi) |
| Population | |
| • Estimate (2009) | 6,300,000 |
| • Density | 58.5/km2 (151.5/sq mi) |
| Time zone | UTC+7 |
The Thai Highlands are a mountainous natural region in the north of Thailand. Its mountain ranges are part of the system of hills extending through Laos, Burma and China and linking to the Himalayas, of which they may be considered foothills.
The highlands of the North of Thailand are characterized by a pattern of generally steep hill ranges, intermontane basins and alluvial gorges. Altitudes are generally moderate, little above 2,000 m for the highest summits. There is a wide range of elevations though, with floors ranging between 500 m and as low as 200 m above sea level. Towards the Lao border the divide to the Mekong basin becomes higher with peaks occasionally rising above 1,500 m and streams flowing in narrow steep valleys.
The climate is typical of tropical mountains with clearly delineated wet and dry seasons. Winter temperatures can be cool with frosts occurring most years at higher elevations, but no snow even on the highest peaks.
The region of the Thai Highlands encompasses the nine administrative provinces of Northern Thailand, based on the six-region system, as well as parts of Tak and Sukhothai provinces.
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All ranges in the north of Thailand are roughly aligned from north to south. The whole system does not have a specific name, but is generally known as Hills of Northern Thailand.[1] Broadly defined, and based on their geological composition, there are two mountainous subsystems:
A great part of the highland area is drained by rivers Ping, Wang, Yom and Nan, all tributaries of the Chao Phraya River. The ranges separating the main rivers are generally steep, high and continuous. Towards the east, as well as in the Wang and Yom drainage basins, they are lower. The Pai River in the northwest flows westwards into the Salween and the northeastern part is drained by rivers of the Mekong basin, like the Kok and Ing.
Geologically in the southern subranges of the Shan Hills layers of alluvium are superimposed on hard rock. The ranges closer to Laos consist of Permo-Carboniferous limestone, which makes for a more jagged and steep relief, despite the more moderate height.[4]
The natural environment of the hills used to be dense montane rain forest. Swidden agricultural practices have much reduced the pristine old-growth forest areas which have been replaced by secondary forest.[5]
For centuries the Thai highlands have been inhabited with hill tribes mostly from Chinese or Tibeto-Burman descent. These human groups immigrated into this relatively empty region fleeing persecution or harsh central rule in their respective environments, as well as seeking new land for their shifting agricultural productions system. For the past decades these groups have been undergoing a process of integration into the Thai mainstream.
Owing to the unrest in Burma, some refugee camps have been established for the cross-border refugees in the Thai highlands.[6] Certain Kayah and Karen communities, like the 'Long-necked Karen', are regularly visited by organized tourist groups.[7]
At higher altitudes, above about 1,000m, one of the main crops was opium until the 1990s, when the combined effects of development became evident - from the construction of roads into the remote area, increasingly efficient policing, and opium replacement programs.[8]
Presently large tracts of the mountains are covered with a mixed vegetation resulting from the capacity of the efficient shifting agricultural system being exceeded. As a result large areas end up becoming dominated by Imperata cylindrica grass, which is used throughout Thailand as roofing material. Cattle can graze on the grass to an extent, as agricultural science research in the 1970s defined.[9] The longer term environmental care of the region is associated with forestry and in the lower reaches, perennial fruit like peaches and other trees. Also some projects for the restoration of forest cover have been undertaken in ecologically degraded areas.[10]