杉木观光木混交林C库与C吸存

对福建三明 2 7年生杉木观光木混交林和杉木纯林C库和C吸存的研究结果表明 ,混交林C库总量为2 2 2 5 0 8t hm2 ,比纯林增加了 2 1 85 %,其中活植物体部分和土壤碳库分别为 139 75 5t hm2 和 80 2 81t hm2 ,分别占C库总量的 6 2 81%和 36 0 8%.混交林和纯林杉木乔木层有机碳年均积累量 6～ 11年最大 ,分别达 7 35t hm2 和 5 79t hm2 .混交林乔木层 2 7～ 2 8年C净固定量为 7 970t hm2 ,折算成CO2 为 2 9 2 2 3t hm2 ,是纯林的 1 19倍 ,其中凋落物和死细根C年归还量分别为 2 5 2 8t hm2 和 0 871t hm2 ,分别是纯林的 1 0 5倍和 1 17倍 ;混交林和纯林中叶和枝C年归还量分别占凋落物C年归还量的 6 6 5 7%、2 3 81%和 6 1 0 3%、2 5 2 0 %;而 <0 5mm的枯死细根C年归还量分别占枯死细根C年归还量 6 0 %和 5 9%.凋落物中叶和枝及 <0 5mm的死细根是该森林生态系统有机碳归还的主体 .

Carbon stock and carbon sequestration in mixed forest of Cunninghamia lanceolata and Tsoongiodendron odorum

The carbon stock and carbon sequestration in a mixed forest of Cunninghamia lanceolata and Tsoongiodendron odorum and a pure forest of Cunninghamia lanceolata at 27-year-old were researched in Sanming, Fujian Province. The total carbon stock of the mixed forest was up to 222.508 t/hm 2, increasing by 21.85% than the pure forest. The carbon stocks of the living parts and the soil of the mixed forest were 139.755 t/hm 2 and 80.281 t/hm 2, respectively, contributing to 62.81% and 36.08% of the total carbon stock of the mixed forest. Annual accumulating amount of organic carbon of the tree layer in the mixed forest and the pure forest were up to the maximum value during 6 to 11 years old, being up to 7.35 t/hm 2 and 5.79 t/hm 2, respectively. Net carbon fixation and net CO 2 fixation of the tree layer were 7.970 t/hm 2 and 29.223 t/hm 2 respectively from 27 to 28 years in the mixed forest, being 1.19 times as much as that in the pure stand. Annual C return through litterfall and dead fine roots were up to 2.528 t/hm 2 and 0.871 t/hm 2, being 1.05 and 1.17 times as much as that in the pure stand, respectively. Annual C return through leaf and branch contributed to 66.57%,23.81% and 61.03%,25.20% of annual C return through the litterfall in the mixed forest and the pure forest, respectively. Annual C return through <0.05 mm dead fine roots occupied 60% and 59% of annual C return through dead fine roots in the mixed forest and the pure one, respectively. Leaf and branch of the litterfall and <0.05 mm dead fine roots were the principal parts of C return to the forest ecosystem.