【作者】 张天宇；

【导师】 宝音陶格涛；

【作者基本信息】 内蒙古大学 ， 草学， 2021， 硕士

【摘要】 土壤团聚体是土壤结构的基本组成单元,其稳定性对于维持草地生态系统土壤结构功能及养分循环具有十分重要的意义。刈割作为天然草地的重要的利用方式之一,长期以来,不同刈割制度对天然草地土壤团聚体稳定性的影响尚不十分明确。为此,本研究以内蒙古典型草原长期割草样地为研究对象,在围封、两年割一次、三年割两次、一年割一次及一年割两次处理下,分别对草地生物量、土壤理化性质、土壤团聚体分布特征、稳定性和有机碳分布特征展开了研究。主要研究结果如下:(1)典型草原在长期不同刈割制度下,刈割措施降低了草地群落地上生物量,并随着刈割强度的增加呈逐渐减小的趋势。围封处理下,各土层土壤含水量以及养分含量最高,随刈割强度的增加而显著减小(P<0.05)。并且随着土壤深度的增加而含量显著降低,土壤p H值变化规律则与其相反。(2)各个处理在不同土层中均以>0.25 mm团聚体居多。长期刈割措施显著降低了0～10 cm土层>2 mm团聚体含量,并随着刈割强度的增加而逐渐降低(P<0.05),其余粒级团聚体百分含量与之相反。10～30 cm土层中,三年割两次、一年割一次和一年割两次处理则以0.25～0.053 mm团聚体居多,团聚体变化规律与表土层相似。(3)长期刈割处理显著降低了各土层的团聚体的稳定性,并且随着刈割强度的增加,团聚体稳定性逐渐减小(P<0.05)。本研究发现,土壤>2 mm团聚体与土壤容重、含水量、土壤养分和地下生物量呈极显著正相关关系,而<0.25mm团聚体与其呈极显著负相关关系(P<0.01)。(4)在长期刈割处理下,0～10 cm表土层的土壤有机碳含量最高,其中有机碳主要分布在>0.25 mm团聚体中,刈割措施显著降低了各土层>2 mm团聚体有机碳(P<0.05),并随刈割强度的增加而逐渐减小。10～20 cm土层的有机碳主要分布于>2 mm和0.25～0.053mm团聚体中,并且随着刈割强度的增加,>0.25mm团聚体有机碳含量逐渐减少,0.25～0.053mm团聚体有机碳含量反而增加。20～30 cm土层中,土壤有机碳主要分布于>0.25 mm团聚体中,并随刈割强度的增加逐渐减小。综上所述,两年割一次处理下各土层大团聚体(>0.25 mm)含量较多,并且团聚体稳定性相对较高,抗侵蚀能力强,有利于土壤有机碳的贮存,更有利于典型草原长期可持续利用。更多还原

【Abstract】 Soil aggregate is the basic unit of soil structure,and its stability is of great significance for maintaining the soil structure function and nutrient cycling of grassland ecosystem.Mowing is one of the important ways of using natural grassland.For a long time,the influence of different mowing regimes on the stability of natural grassland soil aggregates has not been very clear.Therefore,For this reason,this study took the long-term mowing sample plot in the typical grassland of Inner Mongolia as the research object.This study explored the effects of four mowing regimes(mowing once every two years,mowing twice every three years,mowing once every year,and mowing twice every year)on the quantity,physical and chemical properties of soil,distribution characteristics of soil aggregates,stability and distribution characteristics of organic carbon.The main findings are as follows:(1)In typical grasslands under long-term different mowing regimes,the mowing measures reduced the aboveground biomass of the grassland,and showed a gradual decrease with the increase of mowing intensity.Under no mowing treatment,the soil water content and nutrient content of each soil layer were the highest,which decreased significantly with the increase of mowing intensity(P<0.05).And with the increase of soil depth,the content decreased significantly,and the change law of soil p H value was the opposite.(2)In each treatments,most of the aggregates were >0.25 mm in different soil layers.Long-term mowing measures significantly reduced the aggregate content of0～10 cm soil layer > 2 mm,and gradually decreased with the increase of the mowing intensity(P<0.05),and the percentage of aggregates in the remaining particle size fractions was opposite.In the 10～30 cm soil layer,the treatments of mowing twice in three years,mowing once a year,and mowing twice a year are mostly 0.25～0.053 mm aggregates,and the change pattern of aggregates is similar to that of the surface soil layer.(3)Long-term mowing treatment significantly reduced the stability of the aggregates of each soil layer,and with the increase of the mowing intensity,the stability of the aggregates gradually decreased(P<0.05).This study found that soil >2mm aggregates had a very significant positive correlation with soil bulk density,water content,soil nutrients and underground biomass,while <0.25 mm aggregates had a very significant negative correlation with them(P<0.01).(4)Under the long-term mowing treatment,the soil organic carbon content in the 0～10 cm surface soil layer is the highest,of which organic carbon is mainly distributed in aggregates >0.25 mm,mowing measures significantly reduce the aggregates of each soil layer >2 mm organic carbon(P<0.05),and gradually decreased with the increase of mowing intensity.The organic carbon in the 10～20 cm soil layer is mainly distributed in aggregates> 2 mm and 0.25～0.053 mm,and with the increase of mowing strength,the organic carbon content of aggregates> 0.25 mm gradually decreases,and the agglomerates of 0.25～0.053 mm Instead,the organic carbon content increased.In the 20～30 cm soil layer,soil organic carbon is mainly distributed in aggregates >0.25 mm,and gradually decreases with the increase of mowing intensity.In summary,the content of macroaggregates(>0.25 mm)in each soil layer under the two-year mowing once treatment is relatively high,and the aggregates have relatively high stability and strong erosion resistance,which is conducive to the storage of soil organic carbon.Conducive to the long-term sustainable use of typical grasslands.更多还原