What would Thailand be like if the
entire Kingdom was flat? Very different, of course. And one very likely
possibility is that there wouldn't be even a single patch of forest left
in this country. The truth is this: Mountains are one of nature's final
strongholds. These days, forests survive mostly on, and around, these
rugged terrains, without which what are now national parks and wildlife
sanctuaries would have long been turned into farmlands and human
|Hill evergreen forest on top of Doi Inthanon.
Viewed from a distance, these upland greenery seem pretty much the
same. But once you're actually up there, you can almost say that each
peak is a different world. Let's take a quick look at some of Thailand's
most prominent summits, starting from the highest-Doi Inthanon in Chiang
Measuring 2,565 metres above mean sea level, the mighty Doi
Inthanon-the core of a national park of the same name-is crowned with a
lush hill evergreen forest. The relatively thick topsoil on the granite
mountain provides a good foothold for large trees which form a vast and
dense canopy that is highly efficient in trapping moisture from the air.
The peak is thus so moist and cool that tree trunks and branches are
shrouded with mosses, ferns and other epiphytes.
It's undeniable that Doi Inthanon plays an important role in water
catchment-it is the origin of several streams and waterfalls. Many of
these streams are tributaries of the Ping River, which drains into the
|Mountains form the core of most
national parks and wildlife sanctuaries.
A similar forest thrives on the second highest summit-the
2,285-metre-high Doi Phahom Pok. However, the situation on this
mountain, which is a part of the Mae Fang National Park, is not quite
the same-much of the original forest has been thoughtlessly stripped off
the mountain to make way for highland agriculture. The destruction of
Doi Phahom Pok serves as a warning of what may finally happen at Doi
Inthanon, unless the ongoing, sporadic encroachments by both farming and
state projects are stopped.
As far as height is concerned, the second runner-up is Doi Luang
Chiang Dao, which towers at 2,195 metres. The mountain, together with
the forest around it, is a designated wildlife sanctuary.
Like the first two peaks, Doi Luang Chiang Dao is also in Chiang Mai,
but the similarity seems to end there. This mountain is not made up of
igneous rock but limestone, which explains its distinctively ragged top.
Being highly susceptible to weathering by carbonic acid, which is
formed when rainwater is mixed with carbon dioxide in the air, the only
places on the limestone mountain where soil can accumulate and where
trees can firmly take root are in valleys between the jagged ridges.
Up on the wind-blown tops of Doi Luang Chiang Dao only grass and
small herbs that do not require much water survive. Lower down, stands
of pine trees, dry evergreen forest, mixed deciduous forest, and dry
dipterocarp (a forest where most of the trees are deciduous) forest
cover the hillsides, from higher to lower altitudes.
Several other mountains in Thailand are flat-backed. One of them is
the Phu Soi Dao which straddles the Thai-Laotian border in Uttaradit
province. The peak is the main feature of Phu Soi Dao national park.
The flat part of the mountain, which is covered with meadows and pine
trees, is 1,800 metres high; the actual peak of the mountain, which
stands in the Laotian side, rises to an altitude of 2,120 metres.
Just off the flat top, vegetation on the moist mountainside changes
drastically into lush hill evergreen and dry evergreen forests, with
mixed deciduous forests in some areas.
The flat upland of Phu Soi Dao is the beginning of the stream that
flows down the slope to feed the Phu Soi Dao Waterfall at the base of
the mountain, and two smaller streams which run into Laos. From the
amount of water that cascades down the Phu Soi Dao waterfall, it is
obvious that forested mountains are efficient at water catchment, no
matter which types of forest they sustain. What really matters is the
fact that the forest should be large enough to perform this natural
The most popular flat-backed mountain, however, is Phu Kradueng in
Loei province. Like Phu Soi Dao, the wilderness on the top of Phu
Kradueng lies on a bed of sandstone, which produces thin layers of sandy
soil. Therefore, as on Phu Soi Dao, the levelled highland of this
national park is blessed with biologically diverse meadows which
intersperse with stands of oaks and pine trees.
|Pha Taem National Park, which is separated from
the forest of Laos by the Mekong River.
However, because it is much larger, the highland of Phu Kradeung is
able to sustain more water than that of Phu Soi Dao. Up on Phu Kradueng
streams never run dry. Besides, there are even wetlands on the flat
In the valley that forms a long, large crack at the heart of Phu
Kradueng, a healthy dry evergreen forest is harboured. In addition, the
mountain supports different kinds of forest on its slopes-from dry
evergreen forests at the foot of the mountain to dry dipterocarp and
mixed deciduous forests and to hill evergreen forests at higher
Standing not so far from Phu Kradueng and even sharing a similar
geological structure is Phu Luang.
|Phu Luang, a natural herbarium.
However, the composition of flora on the flat back of this mountain
is much richer than that of its neighbour. Pine trees are not so
prominent in this wildlife sanctuary, but the flat-topped peak boasts a
rich variety of herbs and shrubs.
There are also patches of dry evergreen forest, grassland and bamboo
groves up there. In addition, various species of ground and epiphytic
orchids are also a common sight.
Other than Phu Kradueng and Phu Luang, the Northeastern region does
not feature many other high mountains. Some forested areas-like Pha Taem
and Phu Jong Na Yoy national parks in Ubon Ratchathani, for example-are
just 500 to 600 metres above mean sea level.
However, if you stand on the steep eastern edges of these parks,
which overlook the low-lying forests of Laos (in the case of Pha Taem)
and Cambodia (in the case of Phu Jong Na Yoy), you'd say you're standing
on a mountain.
|Pine-studded meadow on Phu Soi Dao.
With sandstone as their geological base, these two Thai forests are
mainly dry dipterocarps, in which trees are not as dense as in the
lowland evergreen forests on the plains on the other side of the border.
With dominant trees shedding their leaves in dry months, the dry
dipterocarp forests may seem lifeless much of the year. But once rains
arrive the entire parks spring back to life-with the trees sporting new
leaves and the ground covered with a variety of fascinating plants and
Seasonal changes are not as remarkable in the forests of the Central
region. Take Khao Yai, for instance.
The park-which comprises several mountains, among which the
1,350-metre-high Khao Rom ranks first in terms of height-shelters mostly
dry evergreen forest, with some mixed deciduous forests, grasslands and
a few patches of hill evergreen forest and dry dipterocarp forest.
|The jagged peak of Doi Luang Chiang Dao.
Also very effective at water catchment, the mountains of Khao Yai are
the sources of dozens of streams and rivers, feeding the five provinces
that surround the park as well as provinces beyond.
The forest's large size also enables it to act as a climate
controller. Supposing Khao Yai was wiped out, it would be possible that
the average temperature in Bangkok and in the entire Central region
The rugged western side of the country is home to several connecting
national parks and wildlife sanctuaries, which when combined with the
forests of Burma across the border, form a very large complex of
In lowland areas, the dominant type of forest is mixed deciduous
forest with some small patches of dry dipterocarp forest. On highlands,
dry evergreen forest and moist evergreen forest are common.
The peak of Khao Luang in Prachuap Khiri Khan province is one of the
highest in the lower part of the western region, measuring at 1,251
metres. Much of the peak, which is part of the Tanao Si range, is
covered with dry evergreen forest. On its misty top, trees are shrouded
with epiphytes like those on Doi Inthanon in the North.
Meanwhile, in the South-the region that enjoys a longer period of
rainfall than the rest of the country-a good example of forest-covered
mountain is Khao Luang in Nakhon Si Thammarat province. Towering at
1,835 metres, the peak supports a hill evergreen forest no less healthy
than that on Doi Inthanon. However, the biologically diverse woodland on
Khao Luang does not suffer as much human interference as Doi Inthanon.
The natural forest is surrounded by rubber plantations and fruit
orchards that help increase the amount of green area and, in turn, the
ability to hold moisture in the soil.
Of course, there are several other forest-harbouring mountains not
mentioned here. And its not just the forests that owe their survival to
the mountains, but also the wild animals that dwell there-and us humans,
the beneficiaries of the natural ecosystems.