植被重建下煤矿排土场土壤熟化过程中碳储量变化

Soil Organic Carbon Storage Changes with Land Reclamation Under Vegetation Reconstruction on Opencast Coal Mine Dump

植被重建是治理因露天煤矿的开采而形成的大面积排土场行之有效的措施,了解植被重建模式对排土场土壤有机碳(SOC)储量的影响是筛选植被治理措施的重要因子.在内蒙古准格尔旗黑岱沟露天煤矿,选取15 a治理排土场中5种植被重建模式(自然恢复地、草地、灌木林、乔灌混交林、乔木林),16种植被配置类型,采集土壤剖面(0~100 cm)样品408个,研究不同重建模式下SOC储量的变化.结果表明:1治理排土场植被重建模式显著影响剖面SOC含量与分布(P<0.05),表层0~10 cm SOC呈草地>灌木>乔木>乔灌混交林>自然恢复地;全氮(TN)也呈相似的变化特征.2植被配置类型中,苜蓿地0~10 cm的SOC含量(5.71 g·kg-1)和TN含量(0.49 g·kg-1)均最高,比自然恢复地分别高166.7%和171.3%,且是沙棘、紫穗槐+油松、香花槐的两倍左右.3植被重建对SOC影响深度主要集中在0~20 cm,而对TN的影响可达40 cm.4与新建排土场相比,植被重建后,草地、灌木地和乔木地0~100 cm碳储量分别增加了15.47、6.93和6.95 t·hm-2,但仅相当于原地貌水平的2/3、1/2和1/2.植被重建表现出碳汇效应和巨大的固碳能力.从土壤固碳的角度考虑,建议植被重建模式以草地为主,植被类型优先考虑苜蓿.

Vegetation reconstruction was an effective solution to reclaim the opencast coal mine dump which was formed in the process of mining. To understand the impact of the vegetation reconstruction patterns' on the mine soil organic carbon ( SOC) storage was essential for selecting the methods of vegetation restoration and also important for accurately estimating the potential of the soil carbon sequestration. The study area was on the Heidaigou opencast coal mine, which was 15 years reclaimed coal mine dump in Zhungeer, Inner Mongolia autonomous region, we selected 5 vegetation reconstruction patterns ( natural recovery land, grassland, bush land, mixed woodland of arbor and bush, arbor land), and 16 vegetation types, 408 soil samples (0-100 m), to study the effect of the vegetation reconstruction patterns on the SOC storage. The results were showed as follow ① on the reclaimed coal mine dump, the vegetation reconstruction patterns significantly affected the SOC content and its distribution in the soil profile ( P﹤0. 05) . The surface 0-10 cm SOC content was grassland﹥shrub land﹥arbor forest﹥mixed forest of arbor and shrub﹥natural recovery land, in which the grassland, shrub land and arbor forest were about 2. 2, 1. 3, and 1. 3 times of natural recovery land (2. 14 g·kg-1 ) respectively. The total nitrogen ( TN) showed the similar trends. ② Among the vegetation types, Medicago satiνa had the highest surface SOC content (5. 71 g·kg-1) and TN content (0. 49 g·kg-1), that were 171. 3% and 166. 7% higher than the natural recovery land, and two times of Hippophae rhamnoides, Amorpha fruticosa+Pinus tabulaeformis and Robinia pseudoacacia. ③The effect of vegetation types on SOC mainly concentrated in the 0-20 cm depth, and the effect on TN accounted for 40 cm. ④ For the SOC storage, the order was original landform area﹥reclaimed dump﹥new dump and grassland﹥woodland ( including arbor and shrub land) . After 15 years revegetation, the soil carbon storage of the grassland, shrub land and arbor land were increased by 15. 47 t·hm-2 , 6. 93 t·hm-2 and 6. 95 t·hm-2 respectively in the 100 cm depth, which were equivalent to 2/3, 1/2 and 1/2 of the original landform levels. The results showed a great ability of carbon sequestration.