This project originates from the Kasetsart University Faculty of Forestry (KUFF), Bangkok, Thailand.

1. Background and Rationale

This project originates from the Kasetsart University Faculty of Forestry (KUFF), Bangkok, Thailand. The rationale for this project is that there is uncertainty in the accuracy of national estimates of Thailand’s forest-cover carbon stocks, incomplete reporting of carbon stocks and limited knowledge of the methods of carbon stocks assessment among the stakeholders. This, in turn, affects the national planning and other policy decisions that rely on information on national carbon stocks.

The carbon stock estimates are inaccurate because the commonly used equations to estimate tree volume are biased (over- or under-estimate tree volume).

The bias occurs because

  1. the sample trees used to develop the equations was small (because of the need to minimize destructive sampling of trees and lack of instruments to accurately measure standing tree upper stem diameters) and, in some cases, not representative of the economy;
  2. some of the equations were local volume equations, which used only DBH as the independent variable and did not include tree height;
  3. the past equations were focused on areas to be logged (mainly big trees), yet, since the national logging ban, the interested has shifted to protected areas that include smaller trees;
  4. the species grouping was too broad (e.g., volume equations by tree family). The commonly used existing equations are the local tree volume equations developed by Pochai and Nanakorn (1992).

These equations developed by the RFD based on upper stem diameter measurements of standing trees using a Spiegel Relascope. However, these equations were developed for one local area in northern Thailand using a small sample of trees. Yet, they are commonly applied nationally. As well, the specific gravity coefficients used to convert volume to biomass were developed based on a small sample of trees. Finally, the generally assumed carbon/biomass fraction of 0.5 (IPCC 2003), for converting biomass to carbon, is too general. The IPCC indicates that “… higher tier methods may allow for variation with different species, different components of a tree or a stand (stem, roots and leaves) and age of the stand …” (IPCC 2003, page 3.25).

A new and novel approach has been developed at KUFF to estimate standing tree carbon content as a function of standing tree attributes (total height and DBH), using sample tree increment cores. Some research has been successfully done by Kasetsart University Faculty of Forestry (KUFF) on ways to directly estimate carbon content on standing trees using wood samples (increment cores) (Duangsathaporn et al. 2011). Other studies have used wood samples to determine carbon content (e.g., Kraenzel, et al. 2003; Wutzler, et al. 2006). Through this project, Thailand sought incremental financial assistance and limited technical support from APFNet to demonstrate this new approach that could be used to develop new national standing-tree carbon equations. These equations could be used to estimate carbon stocks in Thailand’s natural forests. This project is to demonstrate this process in sector Mae Huad, Ngao Demonstration Forest in Lampang province.

2. Goal and Objectives

  • Overall Goal: To provide accurate information on national forest carbon stocks to support SFM policy-decision making.
  • Specific Objective: To demonstrate the development of accurate standing tree-carbon equation and their application to the preparation of a forest-cover carbon stock map.

3. Expected Outcome

  • Methodology to construct and apply tree carbon equations is available.
  • An action plan for development of national standing-tree carbon equations is available.
  • Information and knowledge from the demonstration project disseminated.