Thung Yai Naresuan West

Thung Yai Naresuan West is the western part of the Thung Yai Naresuan Wildlife Sanctuary, covering about 2,130 km² (1,331,062 rai) and managed from Ban Pong. The whole sanctuary covers about 3,647 km² and is the largest protected area in Thailand, lying on the western border with Myanmar in the southern Dawna Range^[1]. With Huai Kha Khaeng it was inscribed as a UNESCO World Heritage Site in 1991.

The sanctuary shelters Indochinese tiger, Indochinese leopard, clouded leopard, sun bear, Asian black bear, Malayan tapir, Asian elephant, gaur, sambar and lar gibbon, and the Western Forest Complex holds around 200 tigers. Birds include white-winged wood duck, green peafowl and all six hornbill species of mainland Southeast Asia. The UNESCO nomination for Thung Yai and Huai Kha Khaeng together listed about 120 mammals, 400 birds, 96 reptiles, 43 amphibians and 113 fish^[1].

Mixed deciduous forest covers about 45% of Thung Yai Naresuan, mostly below 800 m, seasonal or dry evergreen forest about 31%, and montane evergreen forest about 15% along ridges above 1,000 m. Savanna forest and grassland, about 4%, occupy the central "thung yai" (big field) of roughly 140 km², and dry dipterocarp forest about 1%^[1]. Botanical knowledge is sparse because most of the area is unexplored.

The terrain is mainly mountainous, with various limestones, massive granite intrusions and smaller outcrops of quartzite and schist. Elevations run from about 180 m at the Vajiralongkorn Reservoir in the south to 1,811 m at Khao Tai Pa, the highest peak^[1]. The Mae Klong and Mae Chan rivers join in the sanctuary to form the upper Khwae Yai.

There are three seasons: hot and wet from May to October, cool and dry from November to January, and hot and dry from February to April. Annual rainfall is 2,000 to 2,400 mm in the west and 1,600 to 2,000 mm in the east, and over 80% of it comes from the southwest monsoon off the Andaman Sea^[1].

Paleolithic, Mesolithic and Neolithic stone tools have been found in the Khwae Noi and Khwae Yai valleys, and the Mon and Karen have lived in the Dawna-Tenasserim region for at least 700 years. Pwo Karen migrated from Burma in the second half of the 18th century, and the Karen call the central savanna a place of revered ascetic hermits^[1]. Hmong villages were removed in the 1980s and early 1990s.

The sanctuary was declared in 1974 after the 1973 crash of a military helicopter carrying officers on an illegal hunting trip. The proposed Nam Choan Dam, which would have flooded about 223 km² of the sanctuary, was shelved in April 1988, and the forest conservator Seub Nakhasathien wrote the World Heritage nomination. It was inscribed in December 1991 with Huai Kha Khaeng^[1].

The sanctuary's main feature is the central savanna, the thung yai, described as the most complete and secure example of dry tropical forest in Southeast Asia^[1]. Its rivers feed the Si Nakharin Reservoir and the Vajiralongkorn Reservoir. The mountain Khao Tai Pa, at 1,811 m, is its highest point.

The western part, about 2,130 km², is managed from Ban Pong, and the sanctuary extends from Sangkhla Buri District in Kanchanaburi into Umphang District in Tak on the border with Myanmar^[1]. It is a strict nature reserve of IUCN category Ia.

About 200 staff and 25 ranger stations patrol around 12,000 km of forest paths in Thung Yai, and the area has long suffered from poaching^[1]. Karen communities that live in the sanctuary have faced resettlement pressure, and an early 1990s resettlement attempt was reversed after public criticism.