Morphology And Assemblage Distribution Characteristics Of Phytolith In Soil Of Moso Bamboo Forest With Different Lithologies

Phytolith analysis has become a hotspot for palaeoenvironmental reconstruction and global carbon sink research,which can provide a reliable basis for the reproduction of palaeo-vegetation and palaeo-climate in geological periods,as well as a reference for global climate change research.The preservation and carbon sequestration capacity of phytolith are related to different lithologies and regional climates.Studies on the carbon sequestration effect of different lithologies on phytolith in Moso bamboo forest soils have been carried out,but the formation of phytolith and soils are affected by regional environments,and the preservation of moso bamboo phytolith in different lithologies in southwest China is less understood,and the carbon sequestration effect of phytolith in Moso bamboo forest soils is still unclear.This paper takes different lithological Moso bamboo forest soils in the southwest subtropical region as the research object,explores the distribution characteristics and burial effects of phytolith in different lithological soils,evaluates its effects on the reconstruction of bamboo forest vegetation and carbon fixation of phytolith,provides a basis for phytolith analysis to accurately restore the ancient environment and ancient vegetation in the southwest,and provides a reference for the evaluation of carbon sink of Moso bamboo phytolith grown in different lithological soils.The main research results are as follows:（1）The characteristics of phytolith assemblage in different lithologies soil profiles are similar,particularly in terms of the content of dominated long saddle phytoliths,bulliform flabellate and elongate phytolith.The vertical distribution of phytolith concentration in soil profiles with different lithologies is different.The soil profile of granite is relatively accumulated in surface,while the limestone is evenly distributed.The sandstone area show a trend of increasing first and then decreasing.Different lithologies p H values affect the burial of phytolith in the soil profile.（2）Different lithologies soils were consistent with phytolith types of Moso bamboo leaves,and the phytolith coefficients were above 56%,indicating that there was a certain correspondence between the soil and the Moso bamboo phytolith assemblages.The bulliforrm flabellate phytolites of different lithologies showed super-representativeness（R>5）,and were best preserved in soil.Acute bulbosus and elongate phytolith were better preserved in most soil layers;Rondel phytolith was better preserved in sandstone and very poorly preserved in limestone and granite;hair cell phytolith was only present in the 0-10 cm soil layer of granite and and were well preserved.The spheroidal phytolith was only present in a few soil layers and was poorly preserved.The burial effect of phytoliths affects the warmth index of phytolith.Therefore,when we use soil phytolith to reconstruct palaeo-vegetation,calibration of soil phytolith should be considered.（3）The Phyt OC of the Moso bamboo leaves on sandstone soil was the greatest,whereas that of the limestone was the least.There was no significant difference in Phyt OC content with different lithologies.The estimated phytolith carbon flux in Moso bamboo leaves is as follows:granite(0.022 t CO₂ha^-1yr^-1)>sandstone(0.017 t CO₂ ha^-1yr^-1)>limestone(0.010 t CO₂ ha^-1yr^-1).The Phyt OC storage in 0-10 cm soil layer is consistent with that of Moso bamboo in different lithologies:granite（0.17 t/hm²）>sandstone（0.10 t/hm²）>limestone（0.08 t/hm²）.The carbon sequestration capacity of the granite developed soil and the Moso bamboo leaves grows on it is better than the other two lithologies.