Decomposition and nutrient release of fine root in Alnus formosana woodland covered with two herbages(Lolium multiflorum lam and natural grass) as well as mixed decomposition of grass root and fine root in woodland with intercropping system of Alnus formosana and Lolium multiflorum lam was studied by buried bag experiment at Danling county in Sichuan province last year.The results showed that the rate of dry weight loss and nutrient release of fine root were different between intercropping system and natural system,after one year's decomposition,the remaining percentages of N,K,Ca in intercropping system were significantly lower than them in natural system,but the remaining percentages of P,Mg and dry weight had no significant difference between the two systems.Mixed root decomposition rate and the release rate of N,P,K,Ca lay between the decomposition rate of single fine root and single grass root,however,its release rate of Mg was higher than them in intercropping system.After one year's decomposition,mixed decomposition significantly enhanced the decomposition rate as well as the release rate of P,K,Mg except for N,Ca.Moreover,the interactions between fine root and grass root were different in the different phase of mixed decomposition.