岷江干旱河谷区岷江柏人工林碳氮储量随林龄的动态

Dynamics of carbon and nitrogen storage of Cupressus chengiana plantations in the arid valley of Minjiang River,Southwest China

研究了岷江干旱河谷区不同林龄岷江柏人工林生态系统碳氮储量及其分配特征.结果表明：岷江柏不同器官的碳含量相对稳定,氮含量则与器官类型密切相关,而土壤有机碳和氮含量均随着人工林林龄的增长而增加.岷江柏人工林植被层、土壤层以及生态系统的碳氮储量随着林龄的增长总体呈增加趋势.13、11、8、6和4年生岷江柏人工林生态系统总碳储量分别为190.90、165.91、144.57、119.44和113.49 t·hm-2,总氮储量分别为19.09、17.97、13.82、13.42和12.26 t·hm-2.岷江柏人工林生态系统碳氮大部分储存于0~60 cm土层,分别占生态系统总储量的92.8%和98.8%,且主要集中于0~20 cm土层,5个林龄平均碳氮储量分别为74.13和7.40 t·hm-2,分别占其平均土壤总碳氮储量（0~60 cm）的54.4%和48.9%.植被层有机碳和氮储量的分配不同,碳储量在乔木层（3.7%）的分配高于林下植被层（3.5%）,而氮储量在乔木层（0.5%）的分配低于林下植被层（0.7%）.不同林龄岷江柏人工林碳氮储量及其空间分布变化明显,且在此年龄段内,岷江柏人工林生态系统能够持续积累有机碳和氮.

The carbon and nitrogen storage and distribution patterns of Cupressus chengiana planta- tion ecosystems with different stand ages in the arid valley of Minjiang River were studied. The re- sults showed that carbon contents in different organs of C. chengiana were relatively stable, while nitrogen contents were closely related to different organs, and soil organic carbon and nitrogen con- tents increased with the stand age. Carbon and nitrogen storage in vegetation layer, soil layer, and the whole ecosystem of the plantation increased with the stand age. The values of total carbon storage in the 13-, 11-, 8-, 6- and 4-year-old C. chengiana plantation ecosystems were 190.90, 165.91, 144.57, 119.44, and 113.49 t ~ hm-2, and the values of total nitrogen storage were 19.09, 17.97, 13.82, 13.42, and 12.26 t ~ hm-2, respectively. Most of carbon and nitrogen were stored in the 0- 60 cm soil layer in the plantation ecosystems and occupied 92.8% and 98.8%, respectively, and the amounts of carbon and nitrogen stored in the top 0-20 cm soil layer, accounted for 54.4% and 48.9% of those in the 0-60 cm soil layer, respectively. Difference in distribution of carbon and ni- trogen storage was observed in the vegetation layer. The percentage of carbon storage in tree layer （3.7%） were higher than that in understory vegetation （3.5%）, while the percentage of nitrogen storage in tree layer （0.5%） was lower than that in understory （0.7%）. The carbon and nitrogen storage and distribution patterns in the plantations varied obviously with the stand age, and the plan- tation ecosystems at these age stages could accumulate organic carbon and nitrogen continuously.