广西不同林龄杉木、马尾松人工林根系生物量及碳储量特征

为了解不同林龄杉木、马尾松人工林地地下根系生物量及碳储量特征,以广西杉木、马尾松主产区5个不同林龄阶段(幼龄林、中龄林、近熟林、成熟林、过熟林)的人工林为研究对象,采用全根挖掘法和土钻法获取标准木根系生物量、灌草根系生物量和林分细根生物量,并测定其碳含量,分析其不同林龄阶段地下根系生物量和碳储量分配特征。结果表明:杉木、马尾松林地下根系总生物量分别在9.06—31.40Mg/hm~2和7.91—53.40Mg/hm~2之间,各林龄阶段根系总生物量总体上呈现随林龄增加而增加的趋势,杉木林细根生物量随林龄的增加呈现出先减后增的趋势,马尾松呈现出逐渐减小的趋势;林分各层次根系碳含量表现为乔木灌木草本、细根;杉木、马尾松地下根系碳储量变化趋势与生物量变化趋势相同,杉木、马尾松林不同林龄阶段各层次根系和土壤细根总碳储量分别在7.56—21.97Mg/hm~2和8.86—29.95Mg/hm~2之间;地下根系碳储量总体上以乔木根系占优势,且随林龄的增大其比例呈增加的趋势。

Biomass and carbon storage in roots of Cunninghamia lanceolata and Pinus massoniana plantations at different stand ages in Guangxi

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.