In situ and Ex situ Conservation of Commercial Tropical Trees - ITTO

values of about 87-155, while the IVI values of other top 5 species ranges fromabout 8-32. The upper-canopy trees (23-30 m. or more), mainly teak, are moreorless touching, but are not densely packed. Many tree species shed leavesduring dry season. Bamboos commonly associated with this forest type areDendrocalamus membranaceus, Bambusa bambos, and B. longispatha.The Mixed deciduous forest without teak, with a more-or -less opencanopy, can be found at the lower north southwards to the western region.Common tree species in the Mixed deciduous forest without teak are Afzeliaxylocarpa, Bombax insigne, Gmelina arborea, Terminalia bellerica,Lagerstroemia calyculata, and L. tomentosa (Kutintara 1998).The species composition of Dry Dipterocarp Forest with Pine: at PhuKhao Kaew – Dong Pak Chom Reserved Forests, Loei province is dominatedby Shorea siamensis, Shorea obtusa, and Pinus merkusii (Table 6). Theecologically important tree species are Shorea siamensis, Dipterocarpusobtusifolius, Shorea obtusa and Pinus merkusii. The associated speciesdiffer from plot to plot. All four 100x100-m plots have different associationtypes of important tree species: Shorea siamensis-Dipterocarpus obtusifolius,Shorea siamensi-Shorea obtusa and Shorea siamensis-Pinus merkusii andShorea obtusa-Pinus merkusii. A better name for this forest type at thisparticular area may be “ the Pine deciduous dipterocarp forest” as describedby Greijmans (2001).The total number of tree species and species diversity indices of 12study sites representing 6 forest types are presented in Table 7. The Tropicalevergreen forest undoubtedly has the highest values of species diversity andtree density. The species diversity indices of the 3 study sites in the Tropicalevergreen forest (Sites 1-3) are 4.721, 5.923, and 5.738 whereas those in theDry evergreen forest (Sites 4-6) are 3.770, 5.380, and 4.014, respectively.Coniferous forests at Nam Nao National Park, Petchabun, and Swamp forestat Bang Nara, Narathiwat have species diversity indices of 2.93 and 3.55, Dryevergreen forest (Sites 4-6) are 3.770, 5.380, and 4.014, respectively. Coniferousforests at Nam Nao National Park, Petchabun, and Swamp forest at BangNara, Narathiwat have species diversity indices of 2.93 and 3.55, respectively.The species diversity indices of the 2 study sites in the Mixed deciduous forest(Sites 10-11) are 4.508 and 3.831, whereas those in the Dry Dipterocarp forest(Sites 14-15) are 2.907 and 3.161, respectively. The Mixed deciduous forestsat Mae Yom National Park (Site 10) and Um Phang Wildlife Sanctuary (Site11) contain greater numbers of tree species than those of the Dry Dipterocarpforests at Phu Khao Kaew – Dong Pak Chom Reserved Forests (Site 14) andPhu Parn National Park (Site 15). The Dry Dipterocarp forests, both at Sites14 and 15, on the contrary contain greater numbers of plant densities than theMixed deciduous forests at Sites 10 and 11.93