Abstract:Cunninghamia lanceolata and Pinus massoniana plantations cover a large area in Guangxi. In the present study, dynamics of biomass and carbon storage in roots of the two types of plantations were investigated. The plantations were selected according to five stand ages, i.e., young forest, middle-aged forest, near mature forest, mature forest and over mature forest. Two methods, i.e., whole soil excavation and soil auger, were adopted for root sampling. Roots were divided according to trees, shrubs, or grass. The results showed that total root biomass in C. lanceolata and P. massoniana plantations ranged from 9.06 to 31.40 and 7.91 to 53.40 Mg/hm2, respectively. Total root biomass increased with stand age. The fine root biomass in C. lanceolata plantations decreased initially but then increased with stand age, but that in P. massoniana plantations decreased with stand age. Root carbon content in different soil horizons changed in the order of tree > shrub > herb roots. Carbon storage in roots of both types of plantations changed similarly to root biomass. The carbon storage of roots in different soil horizons ranged from 7.56 to 21.97 and 8.86 to 29.95 Mg/hm2, respectively, for C. lanceolata and P. massoniana plantations. Overall, the carbon storage of roots was dominated by tree roots that increased with forest age.
