Effect of α-Pinene on the Fate of Microorganisms and Soil Organic Carbon Content in Eucalyptus and Corymbia Plantation Forests

Abstract

α-Pinene is secreted by some tree species including Eucalyptus grandis and Corymbia torelliana. This monoterpene is known to affect microorganisms and therefore it could affect soil microbial processes including organic matter (OM) decomposition. To study the effect of α-Pinene on soil microorganisms and soil organic carbon (SOC), we analyzed the soils taken from 7-years-old E. grandis and C. torelliana plantations in Passara, Sri Lanka for total organic carbon (TOC), microbial biomass carbon (MBC), bacterial and fungal populations, and α-Pinene content. As the control, the soils of an adjacent grassland were tested. The results revealed that E. grandis plantation had the highest TOC, MBC, bacterial population and α-Pinene content while the lowest of these parameters were observed in grassland soil including the highest fungal population. Interestingly a significant positive correlation was observed between α-Pinene content and TOC in soils of the study sites (P =0.000). The results also indicated a significant positive correlation between α-Pinene content and, the bacterial population while the fungal population showed a significant negative relationship (P<0.05). When the fungal population is retarded possibly due to the activity of α-Pinene, the decomposition process could also slow down resulting in more TOC in plantation soils. Therefore, we could mention that α-Pinene content in soil could affect soil microorganisms and their processes and therefore, it can be considered as an important factor that determines carbon sequestration potential in plantation forest soils.