植被重建下露天煤矿排土场边坡土壤碳储量变化

VARIABILITY OF SOIL ORGANIC CARBON STORAGE IN DUMP SLOPE OF OPENCAST COAL MINE UNDER REVEGETATION

植被重建是治理排土场边坡水土流失最直接也是最有效的生物措施,研究不同植被重建模式下土壤有机碳（SOC）和全氮（TN）含量的空间分布规律是筛选适宜排土场边坡生长的植被模式的重要条件。选取内蒙古黑岱沟露天煤矿治理15年的排土场边坡中4种植被重建模式（自然恢复地、草地、灌木林、乔木林）,采集270个土壤剖面（0~100 cm）样品,研究不同重建模式下SOC储量的变化。结果表明：（1）植被重建模式显著影响剖面SOC、TN含量及分布（p〈0.05）,0~10 cm和10~20 cm SOC、TN均呈草地〉灌木〉乔木〉自然恢复地,20 cm以下各土层SOC、TN虽然也表现相似的特征,但差异随土层深度增加越来越小。（2）剖面SOC密度和储量表现为原地貌区〉治理排土场〉新建排土场。经15年植被重建后,排土场边坡表现出巨大的固碳能力,1 m深度的林地和草地碳储量分别增加了5.38、11.85 t hm^-2,但仅原地貌水平的1/2和3/5。（3）林地和草地的固碳速率分别为35.87、79.01 g m^-2a^-1,草地的固碳速率是林地的2.2倍,从土壤固碳及水土流失防治的角度考虑,建议矿区排土场边坡植被重建优先选择草地,其次灌木。

Vegetation reconstruction is the most direct biological measure and the most effective one as well to control soil and water losses from dump slopes of an opencast coal mine. The knowledge of spatial distribution variability of soil organic carbon （SOC） and total nitrogen （TN） contents in the dump slope as affected by revegetation pattern is essential to selection of proper vegetation patterns that fit the dump slope. The study area was set in the Heidaigou opencast coal mine in Inner Mongolia Autonomous Region, where the dump slopes had been under management for 15 years, using 4 revegetation patterns （natural recovery land, grassland, shrub land, woodland）. A total of 270 soil profiles （0 - 100 cm） were collected as samples for analysis of variability of SOC storage as affected by revegetation pattern. Results show as fol- lows： （ 1 ） Revegetation patterns significantly affected SOC and TN contents and their distribution in the soil profile （p 〈 0.05）. In terms of SOC and TN contents in the 0 - 10 cm and 10 ~ 20 cm soil layers, the four revegetation patterns dis- played an order of grassland 〉 shrub land 〉 woodland 〉 natural recovery land, while in terms of SOC and TN contents in the soil layers below 20 cm, a similar trend could be found, but the differences between the four narrowed with increas- ing soil depth. （2） In terms of SOC density and storage, an order of undisturbed land 〉 managed watershed 〉 managed dump 〉 new dump was found. After 15 years of revegetation, the dump slopes demonstrated a tremendous carbon seques- tration capacity. The SOC storage in the 1 m soil layers of the woodland and grassland was 5.38 t hm 2 and 11.85 t hm 2, respectively, higher than that in the new dump, but only reached 1/2 and 3/5 of that in the undisturbed land. （3） The carbon sequestration rate of the woodland and grassland was 35.87 g m ^-2 a ^-1 and 79.01 g m ^-2 a ^-1 , respectively. The latter was 2.2 times of the former. From the perspective of soil organic carbon sequestration and soil erosion control, grass- land is the＇priority revegetation pattern recommended for management of dump slopes of opencast coal mines and followed by shrub land.