Organic Carbon in Wetland Soil: Seasonal Flooded Forest, Northeastern Thailand

Abstract

Seasonal flooded forest is one of the most important wetlands in northeastern Thailand, not only for its abundant biodiversity, but also as a source of carbon sequestration. Organic carbon plays an specially important role in the soil carbon cycle. To reinforce comprehension on soil organic carbon, five profiles in a northeast plateau were observed and determined. The most common trees were Albizzia Odoratissima, Combretum quadrangulare Kurz, and Streblus asper Lour. The contents of Soil Organic Carbon (SOC) varied from 3.52 g/kg to 5.90 g/kg in top soil and varied from 4.01 g/kg to 4.60 g/kg in sub soil. There was a close relationship between SOC content and basic soil properties, especially the bulk density of both top soil layer and sub soil layer. The distribution of SOC content was harmonized with distribution of plants. In comparative analysis, the flooded forest that composted with a high percentage of vegetation coverage (Khud Tew, Khud Chi Tao) had a significantly higher SOC content. The SOC storage varied from 2.65 kg/m2 to 4.18 kg/m2. Khud Chi Tao contained the maximum amount of SOC storage, whereas Kwo Chi Yai had the minimum. Limitation of flooded forest survival concerned over landscape change, particularly plant disappearance and waterlogged shortage. Therefore, vegetation and hydrology management have to be implemented practically to retain the existing organic carbon in wetlands and allow the soil to sequester additional carbon.