Distribution Characteristics And Carbon Sequestration Potential Of Phytoliths In Alpine Meadows

Phytoliths are produced in plant cells and intercellular spaces,and their morphology is related to the location and shape of plant cells and the growth environment of plants.There are differences in the morphology of phytoliths in different plants and different organs of the same plant.Therefore,the morphology of phytoliths often has good plant taxonomic significance and environmental indication significance.In addition,phytolith will seal a part of organic carbon during the formation process.Due to the stability of phytolith itself,phytolith-sealed carbon is considered to be a long-term effective and stable carbon sequestration mechanism in terrestrial soils.As the grassland ecosystem with the highest altitude and the most unique type in the world,alpine meadow plays an important role in phytolith carbon sink due to its high net primary productivity and numerous silicon-rich plants.By exploring the morphological characteristics of phytoliths in different parts of different families and genera in alpine meadows,the research results of plant phytolith morphology can be enriched,in order to provide reference for the reconstruction of paleovegetation and plant classification in this region;By analyzing the distribution characteristics of phytolith,the occluded carbon of phytolith,and Phyt OC in alpine meadow plants,it can provide a basis for the study of phytolith carbon sink in alpine meadow;By studying the effects of grassland degradation on soil phytolith and Phyt OC accumulation in alpine meadows,it is possible to determine the changes in plant species during grassland degradation,in order to contribute to grassland restoration.In this study,50 common plants in alpine meadows and 4 kinds of meadow soils(0~30 cm)with different degrees of degradation were used as the research objects,and the wet digestion method was used to extract phytoliths from plants and soils.The typical phytolith types of different plants were identified and determined,and the distribution rules of phytolith and Phyt OC in plants and soil were analyzed.Through the above research,the following conclusions were drawn:1)The total number of phytoliths in the aerial and underground parts of the 50 plants were 110~21213 and 47~18874 respectively;a total of 54 phytolith morphologies were identified,and there were many phytolith morphologies in different families and genera.The morphologies and quantities of phytolith were the most abundant in Poaceae and Cyperaceae;almost all plants had their own typical phytolith morphologies,and some plants contained unique phytolith morphologies.2)The phytolith content in the aboveground and underground parts of the 20 plants was 2.449 g·kg-1~33.590 g·kg-1 and 3.168 g·kg-1~31.375 g·kg-1,respectively.The Phyt OC content in the aboveground and underground parts of plants was 0.004 g·kg-1~0.230 g·kg-1 and 0.003 g·kg-1~0.213 g·kg-1,respectively.The distribution of phytolith and Phyt OC content basically followed the distribution rule of aboveground > its underground,and the accumulation of phytolith and Phyt OC was the most in Poaceae and Cyperaceae.3)The content distributions of phytolith,the occluded carbon of phytolith,and Phyt OC in the meadow soils with different degrees of degradation all showed the phenomenon of surface enrichment and decrease with the increase of soil depth;Grassland degradation affected the accumulation of phytolith and Phyt OC in the soil.The soil phytolith and Phyt OC storage in the non-degraded,lightly degraded,moderately degraded and seriously degraded meadows were 10.925 t· ha-1,16.102 t· ha-1,13.657 t· ha-1 and 8.508 t· ha-1 and 0.091 t· ha-1,0.286 t· ha-1,0.089 t· ha-1 and 0.096 t· ha-1,in which the content of each index in the lightly degraded meadow soil was the highest.