Assessing Above Ground Carbon Storage Capacity in D. alatus and its Related Factors in Four Northeastern Provinces, Thailand

Abstract

Dipterocarpaceae are Asian tropical forest trees, which are in a key-category of land ecosystems and are confronted with the world’s highest levels of habitat conversion and associated biodiversity loss. Dipterocarpus alatus is the ninth most conserved plant within the Plant Genetic Conservation Project Under the Royal Initiation of Her Royal Highness Princess Maha Chakri Sirindhorn (RSPG). It is found all over Thailand, and various parts can be utilized for food, energy, cosmetics, medicine, and the creation of other pharmaceutical products. Space technology, satellite data and geographic information system (GIS) have been applied in various fields and are useful for development planning to promote the cultivation of various crops. GIS technology can rapidly work to collect large quantities of display data. This study aims to evaluate the key factors influencing D. alatus planning by using GIS to analyze suitable areas and study the carbon storage in biomass within 19,304,551 rai of Roi-et, Khon Kaen, Mahasarakham, and Kalasin provinces which are in the northeastern region of Thailand. It is intended to serve as a guideline for developing and promoting the cultivation of resin trees as a source of carbon dioxide sequestration to reduce greenhouse gas problems and global warming, as well as help promote the economy and the environment effectively in the future.

This study was divided into two stages. In stage 1, data preparation was used to determine the criteria for the suitability of each factor based on previously studied work. Then, data regarding the suitability of each factor were used to analyze the overlay with GIS. Stage 1 used four factors: soil physics properties, soil chemistry, climate in terms of rainfall and topography. Each factor was assigned a suitability-weight-value to study the growth of resin trees in relation to the overall suitability data based on the previously studied work. Data overlays were analyzed with GIS. The area was divided into four levels of suitable areas for growing resin trees, ranging from very suitable to unsuitable. For stage 2, a random two-year-old resin tree field survey was conducted to find the mean plant height, circumference at chest level, and above-ground biomass, which are standard measurements. In addition, the nine plots were rated from the most suitable to the least suitable over an area of 4500 m².

The results of the study were as follows: 1.) according to the GIS overlay, plot 1 was in the map that was very appropriate with the mean diameter at chest level (DBH) of 2.43 cm, and the mean height of the resin trees was 2.92 m. Plots 2 to 7 were in the map that was moderately appropriate; the mean DBH was 2.14 cm and the mean height of the resin trees was 2.59 m. Plots 8 to 9 were on the map that was less appropriate, with a DBH of 1.94 cm. 2.) In plot 1, the assessment of above ground biomass was very appropriate due to the average carbon storage being 0.71 kg/tree, moderate soil quality, and a very suitable acid-base. Plots 2 to 7 were of moderate suitability because the average carbon storage was 0.51 kg/tree, and there was moderate soil quality and a moderately suitable acid-base. Plots 8 to 9 were deemed to be low suitability due to having an average carbon storage of 0.37 kg/tree, low soil quality, and low acid-base. The most suitable plot had 4,093,243 rai. Moreover, fieldwork of surface area surveys found that the biomass was 124.66 kg/rai and carbon storage was 85.59 kg/rai. These results indicate that the four indicators corresponded to the field survey appropriately, and were able to determine the suitability of resin tree plantations associated with reducing carbon dioxide, thereby lowering greenhouse gases that cause global warming and are a danger to human health.