In southern Myanmar (formerly Burma) three types of seasonal forest have been identified: two in the Irrawaddy Basin and a west coastal forest.

Irrawaddy Dry Forest

These forests are found in the dry zones of central Myanmar where what little rain that does fall usually occurs in torrential downpours. The soils substrates are largely soft sandstones and clays with very little subsurface moisture retention. This together with high levels of surface runoff can cause extreme dryness. The most common trees are Tectonia hamiltoniana and Terminalia oliveri, while associate trees include Acacia catechu and Bauhinia racemosa. There are also stands of dipterocarps and, in fact, Dipteocarpus tuberculatus can form pure stands. Others include Shorea oblongifolia and Pentacme siamensis.

Irrawaddy Moist Deciduous Forest

These typically occur on well-drained hilly terrain up to an altitude of about 1000 m. They are not confined to the Irrawaddy Basin but also occur along the Chindwin, Salween and Sittang rivers. In the Irrawaddy Basin they extend over large areas in the Pegu Yoma region. Canopies are usually closed and can reach heights of up to 30 m. The dominant canopy species are Tectonia grandis (teak) and Xylia kerri (ironwood), but composition varies and often includes bamboo groves. Other tree include Berrya ammonilla, Ginelina arborea, Homalium tomentosum, Lannea grandis, Millettia pendula, Mitravgyna rotundifolia, Odina wodia, Pterocarpus macrocarpus, Salmalia insigni, Terminalia belerica, T. pyrifolia and T. tormentosa.  Among the bamboos Bambusa polymorpha and Cephalostachyum pergracile are the most common, but in the north Dendrocalamus hamiltonii and D. membranaceus become conspicuous. The undergrowth typically includes Barleria strigosa and species of Leea.

Coastal Rainforest

These evergreen and semi-evergreen forests are found on the western side of the Arakan Yoma and Tenasserim mountains ranges on the west coast. They also extend into southeast Bangladesh. These lush forests are largely dominated by dipterocarps mainly Anisoptera glabra, Dipterocarpus alatus, D. obtusifolius, D. pilosa, D. turbinatus, Hopea odorata, Lagerstroemia calyculata, L. floribunda, L. speciosa, Parashorea stellata, Pentace birmanica and Swintonia floridunda. The undergrowth includes Calamus palms and the creeping bamboo Temostachyon helferi. There are also stands of mixed delta scrub and low forest characterized by Calophyllum amoenum, Diospyros burmanica, Elaeocarpus hygrophilus, Litsea nitida and species of Eugenia. Here the undergrowth is mainly Calamus erectus and Pinanga gracilis.

References

Blasco, F. 1983. Southeast Asian Savannas.  In: Ecosystems of the World 13 - Tropical Savannas. Ed. F. Bourliere. Elsevier Scientific Publishing Company.

Chatterjee, D. 1939. Studies on the endemic flora of India and Burma. Journal of the Royal Asiatic Society of Bengol, 5: 19-67.

Gopal, B. & Krishnamurthy, K. 1993. Wetlands of South Asia. In: Wetlands of the World: Inventory, ecology and management. Vol. 1. Eds. D. Whigham, D. Dykyjova and S. Hejny. Kluwer Academic Press.

Kurz, S. 1877. Forest Flora of British Burma. Government of India.

Rao, A. S.  Vegetation and Phytogeography of Assam - Burma. In: Ecology and Biogeography in India. Ed. M. S. Mani. Dr W. Junk Publishers. The Hague.

Stamp, L. D. 1924. The Vegetation of Burma from an Ecological Standpoint. University of Rangoon.