Insights Into the Amazing Biodiversity of Khao Sok
When you’re based at Anurak Community Lodge the amazing variety of mother nature is right on your doorstep. Khao Sok National Park and its adjacent nature reserves are so rich in flora, fauna and impressive geographical landscapes that it’s difficult to know where to start getting your head around this 3500 sq km ecological gem. First of all, it’s mind boggling to realise that you’re walking on a remnant coral reef system that stretched across much of Asia in the Permian period some 280-225 million years ago. Evidence suggests the reef was about five times as big as the Great Barrier Reef of today and stretched from China to Borneo. Those impossible, beautiful vertical limestone karst cliffs were once undersea. If you’re a rock climber you can find marine fossils at the top of a cliff.
In the Ice Age sea levels were much lower and mammal species migrated with ease from the land masses now known as Borneo, Sumatra, Java and Malaysia to what is now southern Thailand. Low sea levels during the Ice Age allowed species that had previously bred in isolation for example in Borneo to migrate to the Thai-Malay peninsula and beyond to Southeast Asia. Tectonic plates were stable in the region and the Ice Age didn’t affect the local tropical climate much. The result was that flora and fauna species in the Khao Sok area evolved over many more millions of years in a state of stability compared to Africa and South America where the biosphere on tectonic plates moved around and were exposed to cooler climates.
Much of the ecological diversity of today is due to a super abundance of fresh water – around 3500 mm (140 inches) annually – and the protection offered by very rugged terrain. The biodiversity is apparent in the plants. In Khao Sok you can find around 200 different floral species per hectare. In the cooler climes of Europe and North America there are around 10 tree species per hectare. In Khao Sok national park you’ll find beautiful tropical plants such as buttress roots, pitcher plants, epiphytes, lianas, figs, dipterocarp trees, and many varieties of banana, bamboo, rattan and palm. Each species has beautifully evolved in its own survival niche. In the profusion of plant life, two species are unique to Khao Sok and nearby areas: the langkow (‘underside white’) palm which grows to 3-5 metres with lovely silver-white undersides; and the stinky, majestic Rafflesia, Thailand’s largest flower and one of the world’s rarest plant species. The flowers are only in bloom for a few days in January or February, the dry season. This is when the petals bloom in ochre, brown and yellow hues up to 80cm in diameter. After blooming for about four days Rafflesia shrivels and dies in a rotting fungal mass, which stinks. As you would expect, the oldest forest ecosystem in the world, holds magnificent mammal and bird life.
Unlike the open Savannah grasslands of Africa, you almost certainly won’t see many big mammals in Khao Sok due to thick forest cover and the fact that most mammals hunt and forage at night. But if you’re lucky you may see the tracks or the scat of some of the following: elephant, wild pig, tapir, tiger, civet, rhinoceros, mouse deer, the Malay sun bear, otter, leopard, a variety of macaques and gibbons, porcupine and monitor lizard. Most species are nocturnal – so that they can avoid the most fearsome predator of them all: man. An estimated 100 or so elephants are thought to inhabit Khao Sok and adjacent sanctuaries. They feed heavily on bamboo and can consume up to 250 kg of vegetation a day – bamboo, leaves, bark, grasses, palm trunks, sugar cane and coconut shoots. You may see clearings through the bamboo groves. These can be made by groups of five or more four- to six-ton elephants grazing and foraging their way through the forest, again, mostly at night. Tigers are the most illusive big cats in the forest, weighing up to 300 kg. No one is sure of their population number. Sightings are very rare. Deer and wild boar is its preferred prey, almost always at night. Clouded leopard, golden cat and leopards also live in Khao Sok. They are also rarely seen. Occasionally there are sightings of the small fishing cat along riverbanks by night. Perhaps the cutest mammal in the forest is the tiny and cuddly-looking slow loris. It is extremely slow moving with large night vision eyes and eats fruit, flowers and insects. The loris isn’t always slow. If necessary, it can reach out and grab an insect in an instant.
Up in the canopy along with the slow loris live macaques, gibbons, gliding lizards, fruit bats, squirrels, around 190 bird species, and the majestic hornbill. The giant hornbill bird, often seen in pairs, is for me the symbol of Khao Sok. The large hornbill with its 152cm (60-inch) wingspan and distinctive large downward-curving bill with a bony cask on the head, consumes a wide variety of fruit and is therefore a good indicator of forest biodiversity. They flourish in Khao Sok, with its abundance of fruit trees, the hornbills dispersing the seeds of rambutan, banana, jack fruit, figs and more. Like sharks, hornbills are thought to be perfectly adapted to their environment with a hundred million years of evolution as a distinct species. Hornbills mate for life and nest in cavities high up in the trunks of large dipterocarp trees.
The human story behind Khao Sok is significant too. Like the karst caves of Krabi, which were inhabited by primitive man around 40,000 years ago, it is likely the forests of Khao Sok held nomadic hunter-gatherer people until recent times. (The Sakai still inhabit the mountains of Trang and the Thai-Malay border further south). It is thought Burmese invasions of the Thai Andaman Sea coast in the 18th century forced Thai natives of the coast to flee inland. They settled in the hills around Takua Pa and ranged east to Khao Sok area where fruit, forest foraging were abundant and the river beds full of tin deposits. Farming and rice cultivation then commenced around the periphery of the forest.
In the 1970s students and others seeking political change in Bangkok fled persecution and took refuge in Khao Sok. The deep forest repelled military attempts to draw them out. At a time when government sanctioned logging companies were laying waste to many forests in Thailand, Khao Sok’s ‘Red’ status and security issues kept the trees beyond the grasping hands of commercial exploitation.
Although Khao Sok became a national park in 1980, the Electricity Generating Authority of Thailand dammed the Pasaeng River in 1982 creating the 165 sq km Cheow Lan lake behind the 95 m high, 700-metre long Rachabrapah Dam. Many valleys were flooded as the reservoir waters rose, leaving the vertical stacks of cliffs rising straight from the water’s surface. It was a disaster for migrating animals, but an aesthetic wonder for visiting humans. Today floating raft houses on the lake are used for adventure tourists and as national park ranger stations.
Khao Sok National Park and its adjacent nature sanctuaries constitute one of the most biologically diverse and visually impressive nature retreats in Southeast Asia. Using Anurak Community Lodge as a base for exploring the park will give rewarding insights into one of the world’s greatest extant examples of tropical biodiversity.
Ken Scott has been working in Thailand and UK in travel journalism and communications since 1986. He returned to UK in 2013, but retains a passionate interest in the culture and nature of southern Thailand, where he lived for eight years. Here he shares insights into wonderful Khao Sok National Park in the South.