"Community dynamics of a tropical seasonally dry forest with special reference to deciduous dipterocarp forest in Northeast Thailand"

Speaker : Dr. Pongsak Sahunalu (CSEAS Visiting Research Fellow and Professor,Faculty of Forestry, Kasetsart University)
Date:15:00-17:00, May 24 (Tue), 2005
Venue:CSEAS East Building, 2nd Floor, E207

To manage and preserve one of the regional important forest types and the native tree species in a relatively minimized human disturbed forest, and/or in a forest fragmentation in a seasonally dry forest type, long-term dynamics of a deciduous dipterocarp forest was investigated to gain the basic information for formulating an alternative future management guideline.

Four stands of deciduous dipterocarp forest were monitored for their changes with time in stand structure, species composition, species diversity, tree death, recruitment and growth over 17 years in a well preserved forest area of the Sakaerat Biosphere Reserves, Nakorn Ratchasima Province, Northeastern Thailand.

Each stand composing of different leading tree species was repeatedly censussed in each 1 ha permanent plot at approximately 1 year interval during 1984 to 2001. All trees with DBH   4.5 cm were marked, numbering tagged, DBH measured, species identified, death trees and trees grew to reach the DBH fixed size at 4.5 cm in each census year counted. Stand structure in terms of stratification, size distribution and crown cover were initially investigated in all 4 stands. Their stratifications were observed to be 2-3 crown layers and size structure followed a negative exponential form. The stands were largely opened with large crown opening (gap) and less lateral crown overlapping. Stand density and stand basal area demonstrated moderately dense and less basal area coverage as contrasted to other forest types. Number of tree species ranged from 32 to 37 and being dominated by most dipterocarp tree species followed by some other families and notably some legumes. Based on their ecological importance value indices, they were classified into 4 different community association types.

Over 17 years monitoring, trees undergone changed with death exceeded recruitment although the total stand density, number of species and basal area increased considerably but size structure of trees in each stand was not drastically changed. The major leading tree species could be maintained in 3 stands while in another one stand some associated leading tree species changed. Leguminous tree species were found to be relatively success in recruitment in the 4 stands. Growth of tree was remarkably rapid for those considered to be the pioneer tree species and those belonging to legume tree group while the dipterocarp tree group was less changed over the period of 17 years. With this relatively good control of stands under the biosphere reserve scheme, this forest community might provide a good sample for future stand prescription in forest management and conservation of local tree species in the future national forest management that local inhabitant will be involved as the manager of community forest in the region.

Coordinator: Prof. Isamu Yamada (Ext. 7310)

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