The Thai highlands or Hills of northern Thailand is 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 in the north of Thailand are characterized by a pattern of generally steep hill ranges,
intermontane basins and alluvial gorges. Elevations are generally moderate, little above 2,000 metres (6,600 ft) for the highest summits. There is a wide range of elevations though, with floors ranging between 200 and 500 metres (660 and 1,640 ft) above sea level.
Towards the
Lao border, the divide to the
Mekong basin becomes higher with peaks occasionally rising above 1,500 metres (4,900 ft) and streams flowing in narrow steep valleys.[1]
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.
Some areas of the highlands are sparsely populated.
Geography
Except for the
Daen Lao Range (ทิวเขาแดนลาว) at the far northern edge, all ranges in the north of Thailand are roughly aligned from north to south. They are linked to a wide system of ranges in neighboring Burma and
Laos that do not have a specific name for the whole, "Thai highlands" being the term generally restricted to the Thai area.[2] Broadly defined, and based on their
geological composition, there are two
mountainous subsystems in Northern Thailand:
In the western part the ranges stretching southwards from the Daen Lao Range, in the southern region of the
Shan Hills or Shan Highland, with the two parallel mountain chains of the
Thanon Thong Chai Range (เทือกเขาถนนธงชัย). This area has the highest elevations, with
Doi Inthanon, the highest point in Thailand, reaching 2,565 metres (8,415 ft). The
Dawna Range (ทิวเขาดอยมอนกุจู) forms the western border of Thailand between
Mae Hong Son and the
Salween River,[3]
The remaining mountainous region of parallel ranges that extend into northern Laos includes the
Khun Tan Range (ทิวเขาขุนตาน), the
Phi Pan Nam Range (ทิวเขาผีปันน้ำ), the
Phlueng Range (ทิวเขาพลึง) as well as the western part of the
Luang Prabang Range (ทิวเขาหลวงพระบาง).[4]
A great part of the highland area is drained by rivers
Ping,
Wang,
Yom and
Nan, all tributaries of the
Chao Phraya River flowing in a roughly southern direction. 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-Carboniferouslimestone, which makes for a more jagged and steep relief, despite the more moderate height.[5] Most of the Thai highlands are part of the
Shan-Thai Terrane, a
tectonic plate.[6]
For centuries the Thai highlands have been inhabited with
hill tribes mostly from
Chinese or
Tibeto-Burman descent, such as the
Akha,
Yao,
Lahu,
Khmu,
Hmong and
Lisu.[9] 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 cross-border refugees in the Thai highlands.[10] Certain
Kayah and
Karen communities, like the "long-necked Karen", are regularly visited by organized tourist groups.[11]
At higher elevations, above 1,000 metres (3,300 ft), 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.[12]
Yearly
wildfires are started by local farmers during the dry season in different areas of northern Thailand. Often speculators also hire people to set forests on fire in order to claim land title deeds for the areas that, post-fire, become "
degraded forest".[13] The smoke produced by these fires is the main cause of the intense seasonal
air pollution in the Thai highlands, also known as the "northern haze".[14] Fires also contribute to the
floods in the country by denuding forest
undergrowth[15] and the dry forest soil leads to lower water intake for the trees to extract when the rains arrive.[16]
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 showed.[17] The longer term environmental care of the region is associated with
forestry and in the lower reaches, perennial fruit like
peaches and other trees.[18] Some projects for the restoration of forest cover have been undertaken in ecologically degraded areas.[19]
^Bunopas, Sangad; Paul Vella (17–24 November 1992).
"Geotectonics and Geologic Evolution of Thailand"(PDF). National Conference on "Geologic Resources of Thailand: Potential for Future Development". Department of Mineral Resources, Bangkok. pp. 209–229. Archived from
the original(PDF (Acrobat 7.x) 1.8 MB) on 12 August 2014. Retrieved 10 August 2014. Thailand consists of Shan–Thai and Indochina Microcontinents or Terranes welded together by the subsequently deformed Nan Suture.... During the Middle Triassic Shan–Thai sutured nearly simultaneously to Indochina and to South China, the continent–continent collision being a part of the Indosinian Orogeny and Indochina tended to underthrust Shan–Thai.
^Gajaseni, Jiragorn; Jordan, Carl F. (1 January 1990). "Decline of Teak Yield in Northern Thailand: Effects of Selective Logging on Forest Structure". Biotropica. 22 (2): 114–118.
doi:
10.2307/2388402.
JSTOR2388402.
The Thai highlands or Hills of northern Thailand is 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 in the north of Thailand are characterized by a pattern of generally steep hill ranges,
intermontane basins and alluvial gorges. Elevations are generally moderate, little above 2,000 metres (6,600 ft) for the highest summits. There is a wide range of elevations though, with floors ranging between 200 and 500 metres (660 and 1,640 ft) above sea level.
Towards the
Lao border, the divide to the
Mekong basin becomes higher with peaks occasionally rising above 1,500 metres (4,900 ft) and streams flowing in narrow steep valleys.[1]
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.
Some areas of the highlands are sparsely populated.
Geography
Except for the
Daen Lao Range (ทิวเขาแดนลาว) at the far northern edge, all ranges in the north of Thailand are roughly aligned from north to south. They are linked to a wide system of ranges in neighboring Burma and
Laos that do not have a specific name for the whole, "Thai highlands" being the term generally restricted to the Thai area.[2] Broadly defined, and based on their
geological composition, there are two
mountainous subsystems in Northern Thailand:
In the western part the ranges stretching southwards from the Daen Lao Range, in the southern region of the
Shan Hills or Shan Highland, with the two parallel mountain chains of the
Thanon Thong Chai Range (เทือกเขาถนนธงชัย). This area has the highest elevations, with
Doi Inthanon, the highest point in Thailand, reaching 2,565 metres (8,415 ft). The
Dawna Range (ทิวเขาดอยมอนกุจู) forms the western border of Thailand between
Mae Hong Son and the
Salween River,[3]
The remaining mountainous region of parallel ranges that extend into northern Laos includes the
Khun Tan Range (ทิวเขาขุนตาน), the
Phi Pan Nam Range (ทิวเขาผีปันน้ำ), the
Phlueng Range (ทิวเขาพลึง) as well as the western part of the
Luang Prabang Range (ทิวเขาหลวงพระบาง).[4]
A great part of the highland area is drained by rivers
Ping,
Wang,
Yom and
Nan, all tributaries of the
Chao Phraya River flowing in a roughly southern direction. 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-Carboniferouslimestone, which makes for a more jagged and steep relief, despite the more moderate height.[5] Most of the Thai highlands are part of the
Shan-Thai Terrane, a
tectonic plate.[6]
For centuries the Thai highlands have been inhabited with
hill tribes mostly from
Chinese or
Tibeto-Burman descent, such as the
Akha,
Yao,
Lahu,
Khmu,
Hmong and
Lisu.[9] 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 cross-border refugees in the Thai highlands.[10] Certain
Kayah and
Karen communities, like the "long-necked Karen", are regularly visited by organized tourist groups.[11]
At higher elevations, above 1,000 metres (3,300 ft), 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.[12]
Yearly
wildfires are started by local farmers during the dry season in different areas of northern Thailand. Often speculators also hire people to set forests on fire in order to claim land title deeds for the areas that, post-fire, become "
degraded forest".[13] The smoke produced by these fires is the main cause of the intense seasonal
air pollution in the Thai highlands, also known as the "northern haze".[14] Fires also contribute to the
floods in the country by denuding forest
undergrowth[15] and the dry forest soil leads to lower water intake for the trees to extract when the rains arrive.[16]
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 showed.[17] The longer term environmental care of the region is associated with
forestry and in the lower reaches, perennial fruit like
peaches and other trees.[18] Some projects for the restoration of forest cover have been undertaken in ecologically degraded areas.[19]
^Bunopas, Sangad; Paul Vella (17–24 November 1992).
"Geotectonics and Geologic Evolution of Thailand"(PDF). National Conference on "Geologic Resources of Thailand: Potential for Future Development". Department of Mineral Resources, Bangkok. pp. 209–229. Archived from
the original(PDF (Acrobat 7.x) 1.8 MB) on 12 August 2014. Retrieved 10 August 2014. Thailand consists of Shan–Thai and Indochina Microcontinents or Terranes welded together by the subsequently deformed Nan Suture.... During the Middle Triassic Shan–Thai sutured nearly simultaneously to Indochina and to South China, the continent–continent collision being a part of the Indosinian Orogeny and Indochina tended to underthrust Shan–Thai.
^Gajaseni, Jiragorn; Jordan, Carl F. (1 January 1990). "Decline of Teak Yield in Northern Thailand: Effects of Selective Logging on Forest Structure". Biotropica. 22 (2): 114–118.
doi:
10.2307/2388402.
JSTOR2388402.