Evaluation of carbon storage in soil and plant biomass of primary and secondary mixed deciduous forests in the lower northern part of Thailand

Carbon sequestration in a forest ecosystem is an important determinant of the local and regional carbon stock. This study monitored forest types and carbon storage in both biomass and soil within primary mixed deciduous forests (PMDF) and secondary mixed deciduous forests (SMDF). One study plot measuring 50 x 50 m and five 10 x 10 m plots were set up at each study site for trees and shrubs inventory, respectively. The trees and shrubs were counted and identified by species. Organic carbon in biomass was estimated by using allometry equation and soil carbon concentration was analyzed by Walkley-Black method. The results revealed that PMDF had a higher level of carbon storage in biomass than SMDF by approximately two times, while soil carbon stock in PMDF was also quite higher than SMDF. The dominant species having a high carbon concentration included Canarium subulatum, Pterocarpus macrocarpus, Dalbergia cultrate, Lagerstroemia tomentosa and Xylia xylocarpa var kerrii. These species were found in intermediate succession, thus indicating that some may be suitable for replanting in future restoration processes in order to accelerate natural succession and storage carbon. This may be one method to reduce the CO2 in the atmosphere by making the SMDF act as a carbon sink.