摘要
The effects of reforestation on carbon （C） sequestration in China＇s Loess Plateau ecosystem have attracted much research attention in recent years. Black locust trees （Robinia pseudoacacia L.） are valued for their important use in reforestation and water and soil conservation efforts. This forest type is widespread across the Loess Plateau, and must he an essential component of any planning for C sequestration efforts in this fragile ecological region. The long-term effects of stand age on C accumulation and allocation after reforestation remains uncertain. We examined an age-sequence of black locust forest （5, 9, 20, 30, 38, and 56 yr since planting） on the Loess Plateau to evaluate C accumulation and allocation in plants （trees, shrubs, herbages, and leaf litter） and soil （0-100 cm）. Allometric equations were developed for estimating the biomass of tree components （leaf, branch, stem without bark, bark and root） with a de- structive sampling method. Our results demonstrated that black locust forest ecosystem accumulated C constantly, from 31.42 Mg C/ha （1 Mg = 106 g） at 5 yr to 79.44 Mg C/haat 38 yr. At the ＇old forest＇ stage （38 to 56 yr）, the amount of C in plant biomass significantly decreased （from 45.32 to 34.52 Mg C/ha） due to the high mortality of trees. However, old forest was able to accumulate C continuously in soil （from 33.66 to 41.00 Mg C/ha）. The C in shrub biomass increased with stand age, while the C stock in the herbage layer and leaf litter was age-independent. Reforestation resulted in C re-allocation in the forest soil. The topsoil （0-20 cm） C stock increased constantly with stand age. However, C storage in sub-top soil, in the 20-30, 30-50, 50-100, and 20-100 cm layers, was age-independent. These results suggest that succession, as a temporal factor, plays a key role in C accumulation and re-allocation in black locust forests and also in regional C dynamics in vegetation.
在高原生态系统吸引了的瓷器黄土的碳(C) 隐遁上的重新造林的效果很在最近的年里研究注意。黑蝗虫树(Robinia pseudoacacia L.) 在重新造林和水和土壤保存努力为他们的重要使用被珍视。这种森林类型越过黄土高原是普遍的，并且一定是任何在这个易碎的生态的区域为 C 隐遁努力计划的一个必要部件。在重新造林仍然保持不明确以后，看台的长期的效果在 C 累积和分配上变老。我们在黄土高原上检验了黑蝗虫森林(后来种的 5， 9， 20， 30， 38，和 56 年) 的年龄顺序在植物(树，灌木，牧草，和叶垃圾) 和土壤(0100 厘米) 评估 C 累积和分配。Allometric 方程为估计树部件的生物资源被开发(叶，树枝，茎没有吠叫，吠叫并且根) 与一个破坏采样方法。我们的结果证明那个黑蝗虫森林生态系统常常积累了 C，从 31.42 Mg C/ 哈(1 Mg = 10 < 啜 class= “ a-plus-plus ” > 6 </sup> g ) 在到在 38 年的 79.44 Mg C/ha 的 5 年。在旧森林阶段(38 ～ 56 年) ，在植物生物资源的 C 的数量显著地减少了(从 45.32 ～ 34.52 Mg C/ha ) 由于树的高死亡。然而，旧森林能在土壤连续地积累 C (从 33.66 ～ 41.00 Mg C/ha ) 。在灌木生物资源的 C 与看台年龄增加了，当在牧草层和叶垃圾的 C 股票是年龄无关的时。重新造林在森林土壤导致了 C 重新分配。C 存货与看台年龄常常增加了的表层土(020 厘米) 。然而，在 2030， 3050， 50100，和 20100 厘米层，在亚顶土壤的 C 存储是年龄无关的。这些结果建议作为一个时间的因素，继任在植被在地区性的 C 动力学在黑蝗虫森林里并且也在 C 累积和重新分配起一个关键作用。
基金
Under the auspices of Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA05060300)
