A forest out of time
At 2,565 meters, the summit of Doi Inthanon is the highest point in Thailand and hosts an ecosystem found nowhere else in the country. This is a true cloud forest, perpetually shrouded in mist, with a cool climate where average daily temperatures hover around 10-12°C. Here, near the peak, exists a rare sphagnum peat bog, a living remnant from a cooler geological period. The bog is a feature of the Ang Ka Nature Trail, a 360-meter-long boardwalk that allows visitors to walk through this primeval environment.
The foundation of this ecosystem is Sphagnum moss, a genus of bryophyte that thrives in the waterlogged and acidic conditions. The moss acts like a giant sponge, creating the bog by retaining vast amounts of water. This creates a low-oxygen environment that dramatically slows decomposition. As layers of dead moss and other plant matter accumulate, they form peat. Scientists have analyzed peat cores from this bog, revealing a local environmental history stretching back at least 4,300 years. Analysis of preserved pollen grains within these peat layers allows researchers to reconstruct past vegetation and climate, indicating that an upper montane rain forest has dominated this area for millennia.
A subtropical island of biodiversity
The unique microclimate of the Doi Inthanon summit supports a distinct collection of flora and fauna with Himalayan affinities. The sphagnum bog is a habitat for the Delavay's rhododendron (Rhododendron arboreum subsp. delavayi), which produces bright red flowers and is otherwise found further north in the Himalayas. The trees in this cloud forest, such as oaks and chestnuts, are draped in a thick coating of epiphytic mosses, ferns, and rare orchids.
This habitat is also a critical area for birdwatching, with over 383 bird species recorded in the park, one of the highest counts in Thailand. Species endemic to these high-altitude forests, like the green-tailed sunbird and the ashy-throated warbler, are found here. The constant moisture and unique vegetation also support a variety of amphibians, including the Doi Inthanon frog. The entire ecosystem shows the past, sustained by the persistent mists that define Thailand's highest peak.