is red-yellow podzolic soil. The extended Southwestern monsoon in May to September brings more than of rainfall to the ecoregion. The temperature remains constantly between throughout the year. Due to the proximity to the Indian Ocean daily temperatures are relieved by the ocean breezes. Relative humidity ranges between 75%-85%. Flora The vegetation of the region is determined primarily by climate, with topography and edaphic conditions contributing secondarily. Two floral communities dominate in the Sri Lankan lowland rain forests - the Dipterocarpus-dominated (Sinhalese "Hora") community and the Mesua-Shorea community (Sinhalese "Na-Doona"). The Dipterocarpus community comprises Dipterocarpus zeylanicus, Dipterocarpus hispidus, Vitex altissima, Chaetocarpus castanocarpus, Dillenia retusa, Dillenia triquetra, Myristica dactyloides, and Semecarpus gardneri. The Mesua-Shorea community comprises Anisophyllea cinnamomoides, Cullenia rosayroana, Mesua ferrea (the national tree of Sri Lanka), Mesua nagassarium, Myristica dactyloides, Palaquium petiolare, Shorea affinis, Shorea congestiflora, Shorea disticha, Shorea megistophylla, Shorea trapezifolia, Shorea worthingtoni, Syzygium rubicundum, and a sub canopy of Chaetocarpus castanocarpus, Garcinia hermonii, Syzygium neesianum, and Xylopia championi. Virgin forests of this ecoregion have four strata, a main canopy at , a sub-canopy at , a understory, and a sparse shrub layer. Trees of the emergent layer reach above the main canopy to . Swamp forests situated closer to the coastlines are a distinct habit area within the ecoregion. Avicennia-Rhizophora-Sonneratia dominated mangroves fringe the coastlines. Biodiversity Almost all the endemic flora and fauna of Sri Lanka are confined to the southwestern rain forests. Due to the warm and moist climate and long physical isolation, wet forest adopted species have promoted a high degree of endemism and specialization. More than 60 percent of 306 endemic tree species of Sri Lanka are restricted to this ecoregion. A further 61 species are shared with the montane rain forests and dry forests. The dominant tree family in Asian rain forests, the family Dipterocarpaceae shows a special endemicity. All but one species of the 58 species of the family Dipterocarpaceae can only be found in these rain forests, including two endemic genera, Shorea and Stemonoporus. Anoectochilus setaceus or Wanaraja (Sinhalese for "King of forest"), an endemic orchid, is only found in undisturbed forests of this ecoregion. Several plant species show highly localized distribution. The lowland and sub montane forests are the floristically richest in Sri Lanka and of all South Asia. Fauna Mammals Sri Lanka lacks the land area to support large animals. Although fossil records of ancestral forms of rhinoceroses, hippopotamuses,