Research area: ThailandResearch areas: Germany, Laos, Thailand, Vietnam
Research sites in NW Thailand: Bor Krai, Huai Bong, Mae Sa Mai
This research area is in Mae Chaem district, Chiang Mai province, and covers around 6.8km2. It extends from N 18° 42’ 31’’ to 44’ 22’’ and from E 98° 14’ 34’’ to 15’ 60’’.
Map of the Huai Bong research area. Full extend.
The elevation ranges from 700 up to 1060m asl. The lowest point is located in the Mae Yot valley at the eastern boundary of the area. The highest point is a mountain peak in the southeastern corner of the area. The average elevation is 810m asl. The southern part of the study area is dominated by mountains which are dissected by SW to NE trending valleys. To the north the mountains are limited by the broad valley of the Mae Yot River. This broad part of the Mae Yot River is trending from NW to SE. Its broad valley bottom ends upstream and downstream at narrow breakthroughs.The incised meandering of the Mae Yot valley in the NE of the area is one indicator of the uplift of the area. The northern part of the area is mountainous, while the northwestern part is characterised by a much gentler surface. The forest consists of deciduous dipterocarp trees and bamboo covering around 60% of the area. Along the larger streams, evergreen trees exist. The first evidence of human influence in the area is given by a tomb in a cave and temple ruins, which are, according to the local people, several hundred years old. Around 500 years ago, Sgaw Karen settled in the Huai Paku village close to the research area. In the 1960’s Huay Bong village was founded (personal communication with the villagers).
Huai Bong village during dry season.
Cropping includes paddy rice in the valley floors and upland rice and maize at higher elevations. During the last twenty years, cash crops like mango, tomato and lychee were introduced. The trend is leading towards intensification of the farming system resulting in permanent cultivation, especially since maize can be sold profitable to a company.
The petrography of Huay Bong is dominated by Carboniferous sediments (sandstone 53%, shale 12%, breccias and conglomerates 10%, marl 6%, claystone 3 %). Additionally, 8% Tertiary sandstone and coal, 7% Quaternary alluvial deposits, and less than 1% Pleistocene conglomerates occur. The Carboniferous sandstone with its intercalations of marl, claystone, breccias, and conglomerate prevails in mountainous areas. This sandstone is composed of 98% quartz and 2% kaolinite. Carboniferous shale exists in the north-eastern and the south-eastern parts. In the north-western part Tertiary sandstone with coal intercalations built up the underground of gently sloping land. Pleistocene conglomerates occur approximately 70m above the Mae Yot River in the eastern part, indicating an uplift of the area. The valley floors of the streams consist of Holocene fluvial deposits. The Carboniferous sequence is in part heavily disturbed by several ancient tectonic events. The Tertiary sandstone contains geodes with plant fossils like Alnus sp. (Betulacea) and Ficus sp. (Moracea), (Late Oligocene) (see Figure below).
Fossil leaves in the Huai Bong area. (A), (C) - (F) Alnus sp. (Betulaceae), (B) Ficus sp. (Moraceae), Late Oligocene.
The Tertiary sequence belongs to a rift basin which might be caused by strike slip tectonics. The Pleistocene conglomerates above the Mae Yot River, a hot spring around 3 km south of the village, and many Holocene landslides along the river vividly display the still ongoing tectonical activity.
Soil mapping revealed that Alisols prevail with 66%, followed by 24% Cambisols, 8% Regosols, 2% Leptosols, and less than 1% Fluvisols (see Figure below).
WRB soil map of the Huai Bong area.
|© Ulrich Schuler