Carbon and Nutrient Release Patterns during Leaf litter Decomposition in Boter-Becho Forest, Southwestern Ethiopia

Abstract

Carbon and nutrient release patterns from decomposing leaves in the forest involve initial leaching, a net immobilization by microbes and a net release phase where the nutrient mass decreases. The aim of this study was to assess the effect of disturbance and season (dry and wet) in the carbon (C) and nutrient release patterns from decomposing leaves. The decomposition of a mixed leaf litter in slightly disturbed (SD) and highly disturbed (HD) sites of Boter-Becho forest was investigated during one year. Litterbags of a mixed leaf litter (20 g each) were buried at a depth of 15 cm in the soils. Residual of mixed leaf litter was monthly retrieved, oven-dried (80°C for 24 h) and weighed. Initial leaf litter and decomposing leaf litter were analyzed for C, total nitrogen (N), available phosphorus (P) and potassium (K). Differences in C and nutrients remaining between seasons and site were evaluated by one way ANOVA at P<0.05. Simple linear regression analysis was performed to predict the nutrient release pattern using initial litter chemistry. The results showed that there was no significant difference between the initial litter chemistry and nutrient release except for K (P=0.021). Moreover, the site had no significant influence on the C and nutrient release patterns except for K (P=0.013). A significant difference was observed (P<0.001) in C and nutrient release pattern between wet and dry season in both sites being greater the release in the wet season. This could be because of the higher temperature and rainfall in wet season which increase microbial activity and thus decomposition rate and nutrient release. Therefore, the rate of decomposition, C and nutrient release pattern in the Boter-Becho forest mainly depend on the climatic factors but not on the initial litter chemistry or site disturbance.