不同放牧强度对锡林郭勒典型草原生产力及碳储量的影响

Effect of Grazing on Plant Biomass and Carbon Storage of Typical Grassland in Xilinguole

以典型草原羊草群落为研究目标,以1979年围封样地为参照(NG),选择轻度(LG)、中度(MG)、重度(HG)放牧样地开展了放牧强度对典型群落生产力及碳储量的研究。结果表明:随着放牧强度的增加,物种丰富度指数、均匀度指数、多样性指数、优势度指数均降低,其中LG,MG和HG均与NG达到显著差异水平(p<0.05),并且均表现出NG>LG>MG>HG变化趋势;随着放牧强度增加,地上生物量和凋落物量呈递减趋势,NG地上植被和凋落物碳储量最高,其大小依次为NG>LG>MG>HG,放牧显著降低了群落的地上植物有机碳储量;随着土层深度的增加,根系有机碳储量呈现减少的趋势,从地下0—60cm根系有机碳储量来看,大小表现为NG>LG>MG>HG,根系总有机碳储量在不同放牧强度间的变化主要受0—20cm根系有机碳储量的影响;土壤有机碳含量随放牧强度的增加呈先增加后减少趋势,随土层深度的增加呈降低趋势,不同放牧强度只对0—40cm土层有机碳含量影响差异显著(p<0.05),在40cm以下土层,其影响不显著(p>0.05),0—60cm土壤有机碳储量序列为MG>LG>NG>HG,MG的固碳能力最强,说明放牧对植被—土壤系统有机碳储量的影响具有非同步性,轻度和中度放牧有助于生态系统有机碳储量的积累,而重度放牧草原生态系统有机碳储量显著降低。土壤碳贮量占总碳贮量的80%以上,是草原碳储量的主体部分,各生态系统有机碳储量比例均表现为土壤>根系>地上植物>凋落物;植被地上碳储量与0—20cm土壤碳储量存在着显著的相关性(p<0.05),回归分析结果表明土壤有机碳储量与土层深度具有较好的相关关系。

Plant biomass and carbon storage of typical grassland in Xilinguole after different grazing intensities(NG,no grazing;LG,light grazing;MG,moderate grazing;HG,heavy grazing)disturbance were studied.The results were as follows.Species richness,evenness,diversity,and dominance significantly reduced with the increase of grazing intensities with the order:NG>LG>MG>HG.The aboveground biomass and litter gradually reduced with the increase of grazing intensities with the order:NG>LG>MG>HG,meaning that grazing intensity reduced plant carbon storage.The root carbon storage gradually reduced with soil depth,which showed the order:NG>LG>MG>HG in 0-60 cm depth,and the effect of grazing intensity on root carbon storage is significant in 0-20 cm soil layer.The content of soil organic carbon decreased progressively with soil depth and showed the enrichment in surface soil layer where the‘surface accumulation’was obvious,while below 40 cm soil layer,there was no significant difference,and the soil carbon storage decreased in the order:MG>LG>NG>HG,which showed moderate grazing was benefit to soil organic carbon accumulation,while heavy grazing would decrease soil organic carbon accumulation.We can conclude that soil carbon storage was the main part of ecosystem with 80%of carbon storage,all parts of carbon storage decreased in the order:soil>root>aboveground>litter.There was significant correlation between plant carbon storage and soil carbon storage in 0-20 cm soil layer(p<0.05),and soil carbon storage had a good relationship with soil depth.