Carbon Accumulation Of Soil Phytoliths In Alpine Grassland And Its Influencing Mechanism

In recent years,Phytolith carbon sequestration,as a long-term and stable carbon sequestration mechanism,plays an important role in the biogeochemical carbon sink of global terrestrial ecosystem.Although predecessors have studied some terrestrial ecosystem phytoliths and their carbon sequestration effects,there are few studies on the carbon sequestration effects and potential of alpine grassland ecosystem phytoliths.Therefore,taking the alpine grassland in Qinghai Province as the research object,through systematic field investigation,sampling design and indoor analysis,this study makes a detailed study on the phytoliths and carbon sequestration effects of alpine meadow,alpine grassland,swamp meadow and temperate grassland in Qinghai Province,reveals the current situation of Phytolith carbon sequestration in different alpine grassland ecosystems in this region,and clarifies the influence mechanism of Phytolith carbon sequestration in alpine grassland,It provides a scientific reference for the study of silicon carbon coupling biogeochemical cycle and carbon sequestration potential of terrestrial ecosystem in the future.The main results of this study are as follows:(1)In different vegetation types,the content of soil phytolith carbon(0-40cm)is the highest in alpine meadow(0.080 g·kg^-1to 0.110 g·kg^-1),the lowest in temperate grassland(0.049 g·kg^-1to 0.089 g·kg^-1),the content of soil phytolith carbon in alpine grassland is 0.043 to 0.085 g·kg^-1,and the content of soil phytolith carbon in swamp meadow is 0.064 to 0.110 g·kg^-1.The variation law of soil phytolith carbon storage(0-40cm)is alpine meadow(0.43±0.004t·ha^-1)>alpine grassland(0.36±0.012t·ha^-1)>temperate grassland(0.33±0.010 t·ha^-1)>swamp meadow(0.20±0.021 t·ha^-1).(2)In temperate grassland,the content of Phytolith carbon was significantly negatively correlated with soil p H,and significantly positively correlated with the content of total nitrogen and nitrate nitrogen.In alpine grassland,Phytolith content was significantly positively correlated with total nitrogen content,Phytolith carbon content was significantly negatively correlated with soil p H,and significantly positively correlated with total carbon and total nitrogen content.In swamp meadow,Phytolith carbon content was significantly positively correlated with total carbon,total nitrogen,ammonium nitrogen and available phosphorus content;In alpine meadow,the content of Phytolith carbon was positively correlated with the content of total carbon,total nitrogen,nitrate nitrogen,ammonium nitrogen and available phosphorus.(3)In swamp meadows with different altitude gradients,the carbon content of soil phytolith(0-40cm)at 2800m altitude is 0.084 to 0.119g·kg^-1,that at 3150m altitude is 0.076 to 0.128g·kg^-1,that at 3750m altitude is 0.064 to 0.11g·kg^-1,and that at 4200m altitude is 0.076 to 0.113g·kg^-1.The change of soil phytolith carbon storage is 4200m(0.47±0.029 t·ha^-1)>2800m(0.32±0.016 t·ha^-1)>3150m(0.28±0.007 t·ha^-1)>3750m(0.19±0.044t·ha^-1).(4)In the swamp meadow at 2800m above sea level,there was a very significant positive correlation between phytolith content and phytolith carbon content.There was a significant positive correlation between phytolith content and total carbon content,and a very significant positive correlation between phytolith carbon content and ammonium nitrogen content.In the swamp meadow at an altitude of 3750m,the content of Phytolith carbon was significantly positively correlated with the content of total carbon,total nitrogen,ammonium nitrogen and available phosphorus;In the swamp meadow at an altitude of 4200m,Phytolith content showed a significant positive correlation with total carbon and total nitrogen,and phytolith carbon content showed a significant positive correlation with total carbon and total nitrogen.It is found that the soil phytolith carbon content is significantly correlated with various nitrogen contents regardless of the difference of different vegetation types or altitude gradients.Due to the different degrees of degradation of the Alpine Ecosystem in recent years,based on the nitrogen deposition in recent years and the application of nitrogen fertilizer on the Qinghai Tibet Plateau,the phytolith carbon storage of the alpine ecosystem on the Qinghai Tibet Plateau can be effectively increased,This is important for further enhancing soil carbon sequestration in the long term.