Included here are the mountains of Thailandwhich include a limestone massif in the Chiang Dao area.

Thailandian Upper Montane Scrub

These upland scrublands have been described as unique and support many endemic species. They are mainly confined to the crests of exposed barren summit areas of the limestone massif in the Chiang Dao District, which range in altitude from 1900 and 2200 m. Despite being called scrublands they are overwhelmingly dominated by herbaceous elements including many temperate genera and species. The low growing shrubs, on the other hand, thrive in the many mossy cracks and crevices giving these communities the appearance of attractive rock gardens. The few trees include a scattering of gnarled oaks such as Quercus franchetii, Q. lanata, Q. semecarpifolia, the palm Trachycarpus martianus and the deciduous, hemi-epiphytic tree Wrightia speciosissima (Scrophulariaceae). Common shrubs are Cotoneaster franchetii, Indigofera dosua, Lespedeza harmsii, Luculia gratissima, Mahonia nepaulensis, Premna interrupta var. smitinandi, Rosa helenae, Sophora dispar, Viburnum atro-cyaneum, Zanthoxylum acanthopodium and the endemic Rhododendron ludwigianum (Ericaceae), which is noteworthy since most rhododendrons are calcifugous species. The parasitic shrub Hymenopogon parasiticus (Rubiaceae) can also be occasionally found on the epiphytic shrub Agapetes hosseana. The principal herbs are spread over at least 25 familes and include many endemic or near endemic taxa such as Corydalis siamensis (Fumariaceae), Delphinium altissimum var. siamensis (Ranunculaceae), Geranium lamberti subsp. siamense (Geraniaceae), Hypericum siamensis (Hypericaceae), Primula siamensis (Primulaceae), Saxifraga gemmipara var. siamensis (Saxifragaceae), Swertia calcicola (Gentianaceae) and Thalictrum siamensis (Ranunculaceae). By comparison with the upper montane forest, the epiphytic flora is not rich, but still comprises many orchids including several endemic species such as Dendrobium continale, D. wilmsianum and Luisia thailandica (Orchidaceae). The principal pteridophytes are Araiostegia pulchra, Asplenium antrophyroides, Cheilanthes farinose, Crypsinus griffithianus, Microsorium membranaceum, Polypodium amoenum and Selaginella repanda.

References

Ogawa, H., Yoda, K. & Kira, T. 1961. A preliminary survey of the vegetation of Thailand. Nature and Life in Southeast Asia, 1: 21-157.

Santisuk, T. 1988. An Account of the Vegetation of Northern Thailand. Franz Steiner Verlag Wiesbaden Gmbh Stuttgart.

Smitinand, T. 1966. The vegetation of Doi Chiengdao – a limestone massive in Chiengmai, North Thailand. Natural History ulletin of the Siam Society, 21: 93-128.