植被重建下排土场扰动及小流域自然土体土壤有机碳储量比较

A comparative study on soil carbon storage between the disturbed soil of the mine dump and the natural soil of the small watershed under revegetation

比较黄土丘陵沟壑区排土场扰动土体和小流域自然土体植被重建下土壤剖面有机碳(SOC)储量的差异,有助于了解区域SOC源汇效应的变化机理;同时,可从土壤碳储量增减的角度为该区域露天矿区土壤修复措施的选择提供一定的参考依据。在黄土丘陵沟壑区,选取内蒙古准格尔旗黑岱沟露天煤矿排土场和五分地沟典型治理小流域,研究了排土场平台与小流域梁峁顶SOC含量的差异、排土场边坡与小流域坡地的SOC储量差异及其影响因素。结果表明:植被恢复与重建模式显著影响表层(0~20cm)SOC和全氮(TN)含量(P<0.05),20cm及以下随土层加深,影响越来越小。1m土层深度的土壤碳(氮)密度及储量表现为经治理的小流域坡地大于排土场边坡,且差异显著,草地模式显著大于林地模式(P<0.05)。1m土层SOC储量与凋落物生物量呈正相关关系(y=alnx+y0,R^2=0.43~0.83),与凋落物含碳量也呈正相关关系(y=ax+b,R^2=0.48~0.78),且草地SOC储量随凋落物生物量和含碳量增加而增大的速率也较林地大。植被重建15年后,排土场边坡林地、草地的SOC储量仍未达到治理小流域坡地的水平。若要通过植被恢复与重建达到此水平,每公顷排土场林地和草地1m土深SOC储量分别需要增加13.64t和11.15t;若每年SOC储量增长匀速,排土场林地和草地SOC储量分别需要25年、21年才能达到目前小流域坡地的水平。

Studying the differences in the soil organic carbon(SOC)storage between the disturbed soil of the mine dump and the natural soil of the small watershed under revegetation enables us to better understand the changing mechanism of carbon source and carbon sink in loess hilly and gully region.At the same time,it can provide some reference for the selection of soil remediationmeasures in the opencast mining area from the perspective of soil carbon storage.The Heidaigou opencast coal mine dump and the Wufendigou small watershed were selected to study the difference of SOC content between the dump platform and the small watershed Liang-maoding and the difference of carbon storage between the dump slope and the small watershed slope land in Zhungeerqi county,Inner Mongolia,as well as the influencing factors.The results are as follows:(1)Revegetation patterns significantly affected the surface(0~20 cm)SOC and total nitrogen(TN)contents(P<0.05),while in the SOC and TN contents in the soil layers below20 cm,a similar trend could be found,but differing with decreasing soil depth.(2)The SOC(TN)density and storage of the small watershed slope was larger than that of the dump slope in 1 msoil layers,and the difference was significant,and the grassland pattern was much larger than that of the woodland pattern(P<0.05).(3)There was a positive correlation between SOC storage and litter biomass(y=alnx+y0,R^2=0.43~0.83),and there was also a positive correlation with carbon content of litter(y=ax+b,R^2=0.48~0.78).The increase rate of the grassland SOC storage with the increase of litter biomass and carbon content was larger than the woodland pattern.(4)After 15 years of revegetation,the SOC storage of the woodland and the grassland in dump slope had not reached the level of the small watershed slope land.To reach the SOC storage of the small watershed,1 hm2 dump slope in 1 mdepth woodland and grassland has to increase13.64 tand 11.15 tSOC respectively;if the SOC storage growing at an even rate each year,it takes 25 years and 21 years for the grassland and woodland of the dump slope to reach the current SOC storage level of the small watershed slope respectively.