Systematic forest inventory plots and their contribution to plant distribution and climate change impact studies in Thailand

Thailand is recognized as having high species richness both flora and fauna. The systematic plant taxonomy and collection was initiated in 1957–58. However, the distribution of specimen collections is uneven and mainly located near road networks. The Royal Forest Department (RFD) has since 2001 initiated the systematic uniformly fixed grids of 20 km × 20 km for measuring trees and their environments with the financial and technical support from the International Tropical Timber Organization. After the reorganization of the RFD in 2002, the Department of National Parks, Wildlife and Plant Conservation of Thailand, which then was separated from the RFD, has carried on this project and added the uniformly fixed grids ranging from 2.5 km × 2.5 km to 10 km × 10 km over the entire protected areas in Thailand. Throughout three project phases (2001-present), there are over 3,150 plots collected from 59 provinces, while the remaining 18 provinces do not have monitoring plots because of either the security issue or no forest covers. There were, based on altogether 24,605 occurrence records of trees with a diameter greater than 4.5 cm at breath high level from 363 species from 81 families and 222 genera. Trees belong to Dipterocarpaceae, Lamiaceae, Burseraceae, Phyllanthaceae, Malvaceae and Fabaceae families are dominant. Besides for simple estimation of tree density and volume, the data were used for bio-geographical and climate change impact studies.