Khao Sok has been very geologically stable over the last 60 million years: while other regions of the world experienced periods of glaciation and shifting climate, Thailand rested in the middle of the relatively stable Indo-Chinese plate, never drifting far from the equator. This long period of stable weather and rainfall patterns have allowed the many species of the area to prosper.
Khao Sok rests near or straddles many features that create different bioregions. The Tenasserim Hills that serve as a continental divide, separating eastern and western regions of the Thai peninsula, run along the edge of Khao Sok National Park. It lies immediately below the Isthmus of Kra, separating the bioregions of peninsular Thailand and Malaysia from the more deciduous, dry regions to the north.
The Kangar-Pattani line south of Khao Sok near the Thai-Malay border separates the jungles of the Orient from the jungles of Indonesia and its surrounding areas. A key distinction of this line is the shift in humidity, as it is markedly higher south of the line.
Let It Rain
Since Khao Sok National Park straddles both sides of the continental divide, it receives heavy rains during the southwest monsoon coming from the Andaman coast and occasional rains during northeast monsoons coming from the Gulf of Thailand, creating one of the highest rainfall totals in all of Thailand at 3.5 meters per year.
Khao Sok’s unusual ecological features include the flora found on the craggy limestone mountains known as karsts. These spectacular cliffs began their life as sea corals. They were uplifted en masse with the Earth’s crust to form the peaks we see today and were subsequently eroded by rain and the rise and fall of the oceans leaving dramatic, sharp and varied shapes.
The lack of soil, extreme desiccation during dry season and varying altitude have created niches for endemic species of plants. The pralahoo palm, langkow palm, and fern palm are examples of species seen in Khao Sok and nearly nowhere else. Rainwater collects on small shelves along karst faces and mixes with decaying plant matter to make a soil that provides just enough for these palms to grow.
A much-admired oddity is a large almost black flower known in Thai as “bat’s whiskers.” But the most famous of all, sometimes called the world’s largest flower, is the Rafflesia. This Rafflesia blooms in Khao Sok Park occasionally for about 7 days in the dampness of the forest and cannot be grown by man. You can discover it yourself on our special Rafflesia Hike.
Many varieties of bamboo, huge climbing vines (lianas), and Rattan are also common. Rattan, commonly used the make cane furniture, grows to lengths of 100 feet, has very prickly thorns, and a sour red fruit which is refreshing to nibble on a hot rainforest trek. Walk slowly through the forest and appreciate the beauty of these plants. Notice too the various strange mushrooms, like the net mushroom pictured here.
Another fascinating oddity prominent in Khao Sok ecology is the strangler fig. The strangler fig is actually a vine although after years of growth it looks like a tree. Its fruit, which is not much different from the fig we eat, is a favorite of the hornbills, gibbons, and other wild animals and birds in the forest. When these animals emit the seed and it falls on a tree, it eventually sends fast-growing roots to the ground. After many years, these roots become large enough to circle and strangle the host tree, which dies and deteriorates, leaving a hollow sometimes big enough to walk into.