Located in Chiang Mai Province, Doi Inthanon National Park encompasses the highest mountain In Thailand, Doi Inthanon, as well as several lesser summits. The doi (mountain) is largely a granite batholith intruding a southerly extension of the Shan Hills range and forming the divide between the Nam Mae Ping river to the east and the Nam Mae Chaem river to the west. Lower elevations in the most easterly pant of the park are limestone formations and contain a number of caves.

     Formerly known as Doi Angka, the mountain now bears (since 1899) a shortened version of the name of Chiang Mai's last sovereign, King Inthawichayanon. During his reign, he had, with great foresight, expressed his concern for the forests of the northern hill country as the watershed for all of central Thailand. The modern study of rain forest hydrology has borne out his early convictions and given substance to Thai folklore which describes this hill region as the home of the Phiphannam, the 'spirit who shares water'. Before the King died near the turn of this century, he commanded that his remains be placed at the top of this mountain: his ashes at the summit stupa are visited by thousands of people each year.

     
      The park covers an area of 48,240 ha. Its lowlands below 800 meters in elevation are warmandverydry during the rain-free season, but the summit of Doi Inthanon, at 2565 meters, has a climate more like Canada than Thailand. The temperature has been known to drop as low as -8 degrees C. and frosts are not unusual during the cool, dry season. January is the coldest month: an average nighttime temperature is 5.5 degrees C. At any season, Doi Inthanon is a comfortable reprieve from the heat of the lowlands. At altitudes above 1000 meters, rainfall exceeds 2500 mm, considerably more than at nearby Chiang Mai. Even in the dry season, November to April, there is rare but occasional rain or the summit may be shrouded in cloud for a part of the day; persistent mist is an important factor in the maintenance of moist forest there.

     The various sub montane forest formations at higher elevations are a unique asset of the park. They have dominant species belonging to temperate climate families rather than tropical. The summit area supports the only red rhododendron in Thailand (R. delavayi); it blooms from December through February. There are also two white-blossomed species abundant on Doi Inthanon which are restricted to only a few other sites.

     Where mists are persistent, the slopes carry a moist hill evergreen or 'cloud forest' with many epiphytes, plants which live on tree trunks and branches but do not receive their moisture and nutrients from the host tree as do true parasitic plants. Instead, they are nurtured by the accumulation of dust particles and humus around their 'root' area and the moisture retained there, augmented by frequent bathing in cloud and mist. Epiphytic orchids are also abundant, along with lichens, lianas and fern.

     At mid-elevations, 800 - 1500 meters, two species of pine are present, Pinus merkusii mixed with dipterocarp in the lower range, and P. kesiya with oak and laurel on drier slopes in the upper range. The pines are thought to be a relic from a prehistoric cooler climatic period when flora from the Sino-Himalayan region migrated southward. At the mid-elevations of the park, much of the forest has been removed by the activities of swidden cultivators and the slopes have converted to fire climax grasslands.

     Birdwatching: Because of its broad altitudinal range and the cool climate of its upper reaches, the park supports the largest number of bird species of any site in Thailand. The Center for Wildlife Research at Mahidol University records a present total of 362 species and expects additions; Many at the summit are migrants from northern Asia. Species restricted to Doi Inthanon are Ashy-throated Warbler and an endemic race of the Green tailed Sunbird; the park is the only site where the Chestnut-bellied Rockthrush and the Yellow-bellied Flowerpecker are known to oversummer and probably breed. Over 190 bird species are listed as common to abundant. Bird lists are available at the Visitor Center and at Park

          Summit of Doi Inthanon (Km 48)

                The drive to the summit offers some fine views, especially during November and December, before the dry season haze has become well established. On your visit to the summit stupa containing the remains of King Inthawidhayanon, be sure to read the English translation on the back of the marble plaque nearby. Photographing any part of the radar station is forbidden, but visitors may take pictures freely of any other subject.

                On the main road and opposite the summit Ranger Station is a sign in Thai marking a short, self-guided nature trail which descends to a sphagnum bog in a small karst depression The bog area. which displays the red blossomed Rhododendron delavayi, comes nearest to a true montane forest formation and is a good location for bird-watching. If you continue around the bog and down a short distance, you will reach a memorial shrine marking the site of a helicopter crash which occurred in the mid-seventies and killed the first superintendent of this park.

          Mae Ya Waterfall (14 km from Chom Thong)

                Thought to be the highest in Thailand and is well worth the extra effort to get there. Park officials estimate that the Mae Ya River plunges more than 250 meters at this point. It is a beautiful, fanning cascade, dropping down an ever-widening series of steps -- without a doubt, a photographic favourite.

           The Mae Chaem road

                 A scenic pleasure. From the start at Km 38 on the main summit road, the first kilometers travel through some of the most lush forest on the mountain. Then the road comes out into the open and follows a descending ridge with fine views.

          Mae Pan Area

                At Km 6.6 on the Mae Chaem road is the turn-off to Mae Pan Waterfall, marked by a sign in Thai and English. The dirt access road descends about two kilometers to the Ranger Station and campground and is suitable for any vehicle although the road can be slippery on the uphill return after a heavy rain. The area is quiet, off the beaten track, and can be described as the back country of Doi Inthanon Park. It offers a rewarding loop hike of 1.5 to 2 hours through untouched terrain with small waterfalls and tumbling creeks along most of the route. Visitors can walk the 800 meters to Mae Pan Falls and back again, as well as the 200 meters to Huai Sai Luaeng Falls just beyond the campground. Both of these trails are clear and well-maintained.

From : www.chiangmai-chiangrai.com