SOIL PHYTOLITH ASSEMBLAGES AND ITS PRESERVATION CHARACTERISTICS UNDER TYPICAL PLANT COMMUNITIES IN THE MID-SUBTROPICAL ZONE OF CHINA
Modern soil phytoliths provide analogs for fossil phytolith assemblages in stratigraphic sequences.To assess the reliability of soil phytoliths for representing different plant communities and their preservation,we collected vegetation samples from plant communities and their corresponding topsoil samples from 39 sampling sites in the mid-subtropical zone of China,and identified 32 morphotypes of phytolith.The Nanling Mountains lie to the south,the Wuyi Mountains to the west,and the Xuefeng Mountains to the east;these three mountain ranges and their adjacent regions(25°07′～30°08′N,108°47′～112°40′E)in Hunan Province are the research area.The vegetation of these sites consists of five communities:forest(evergreen broad-leaved forest,evergreen and deciduous broad-leaved mixed forest,deciduous broad-leaved forest),shrub,and herbaceous communities.Using principal component analysis and discriminant analysis,we assessed the feasibility of quantitatively distinguishing different plant communities based on phytolith assemblages.The results showed that the soil phytolith assemblages among the different plant communities were different,and different plant communities could be quantitatively distinguished to a certain extent based on soil phytoliths.Among them,the phytolith assemblages in herbaceous communities were dominated by grass silica short-cell phytoliths(GSSCP),elongate,and acute bulbosus(88.2％);shrub communities exhibited the high frequencies of grass silica short-cell phytoliths(GSSCP)and tabular(67.6％),and forest communities were dominated by grass silica short-cell phytoliths(GSSCP),tabular,and silicified stomata(64.4％).Additionally,using R-values,we studied the quality of soil phytolith preservation,and found that soil phytoliths among different plant communities showed varying degrees of preservation.The preservation of soil phytoliths was best within the forest community(R-values average of 0.07),intermediate in the shrub community(R-values average of 0.01),and worst in the herbaceous community(R-values average of 0.005).Additionally,the preservation of soil phytoliths within evergreen broad-leaved forest(R-values average of 0.16)was better than that within deciduous broad-leaved forest(R-values average of 0.039);and soil phytolith preservation in evergreen and deciduous broad-leaved mixed forest(R-values average of 0.037)was like that in deciduous broad-leaved forest.Specifically,some morphotypes(e.g.,bulliform flabellate,blocky rectangular,acute bulbosus)were well-preserved in the soil(R-values＞4.00);bilobate,rondel,crenate,elongate psilate,elongate tabular,elongate dentate,and tabular irregular were moderately well preserved(0.15＜R-values＜4.00);and other types(e.g.,favose,silicified stomata,epidermal cell irregular,hair)were poorly preserved(R-values＜0.15).Our findings help understand taphonomic processes affecting soil phytoliths,and help improve the accuracy of phytolith-based paleovegetation reconstruction in the mid-subtropical zone of China and potentially elsewhere.
phytolithmid-subtropical zone of Chinaplant communitypreservation
万方数据
维普
