科尔沁沙地优势植物叶凋落物分解及碳矿化——凋落物质量的影响

Carbon Mineralization and Decomposition of Litters from Dominant Plants in the Horqin Sandy Land:Effects of Litter Quality

凋落物矿化分解是维持生态系统养分循环的关键过程,也是陆地生态系统C向大气释放的主要动力,因此影响和控制生态系统凋落物矿化分解的主要因素一直备受关注。土地沙漠化是科尔沁沙地最严重的环境问题,并且导致土壤粗质化和贫瘠化,凋落物输入和矿化分解对于改善该地区土壤质地和养分状况至关重要。通过室内培养的方法,对科尔沁沙质草地27种主要植物叶凋落物矿化分解及其与凋落物C含量、N含量、木质素含量、C/N、木质素/N、极易分解有机物含量(LOMⅠ)、中易分解有机物含量(LOMⅡ)及难分解有机物含量(RP)等指标关系进行研究。结果表明:科尔沁沙地27种植物叶凋落物质量存在较大差异(P<0.001),相应的27种植物叶凋落物培养样品矿化有机碳总量和干物质损失量存在显著差异(P<0.001),分别在9.0mg C·g^(-1)干土至12.7mg C·g^(-1)干土和14.7%至40.4%之间变化。添加凋落物后培养样品的CO2释放总量显著大于对照(不添加凋落物),说明土壤中添加凋落物后,培养样品的有机碳矿化速率明显增大。27种植物叶凋落物矿化有机碳总量以及损失干物质总量与凋落物的N含量、C/N、木质素/N、LOMⅠ、LOMⅡ和RP等指标存在显著的相关性,叶凋落物的矿化分解主要受LOMⅠ和木质素/N的影响。

Carbon（C）mineralization and decomposition of litters is a critical process to maintain ecosystem nutrients cycling,and drives the large flux of terrestrial C to atmosphere.Therefore,the factors that control the litter decomposition in terrestrial ecosystem are focused on all the time.Horqin Sandy Land is one of the regions that suffering severe land desertification in north China.As a result,soils in this region were coarsened and impoverished.Litter input and subsequent C mineralizing and decomposing would improve soil texture and nutrients in this region.In this study,C mineralization and decomposition of litters from27 plant species were investigated by adding litter into soil and incubating it in laboratory.Subsequently,we analyzed the correlations of total CO_2 release and dry mass loss with C concentration,N concentration,lignin concentration,C/N,lignin/N,labile Pool I and II,and recalcitrant Pool in litter.The results showed that there were big differences in litter quality among 27 plant species,and correspondingly total CO_2 release and dry mass loss also differed greatly and varied from9.0 mg C·g^（-1） dry soil to 12.7 mg C·g^（-1） dry soil and from14.7%to 40.4%,respectively,among 27 plant species.Total CO_2 releases after adding litter were significantly larger than the control（non-addition of litter）,suggesting that litter input would accelerated C mineralization.Correlation analysis showed that total CO_2 release and dry mass loss were significantly correlated with N concentration,C/N,lignin/N,labile pool I and II,and recalcitrant pool in litter of 27 plant species.Stepwise regression,however,suggested that C mineralization and mass loss of litter were mainly controlled by labile pool I and lignin/N in 27 plant species.