Standardization of two forms of the CRENATE (Pooideae Benth.) phytolith morphotype and their potential for environmental reconstructions

The separation of two forms of Crenate phytoliths from the epidermal short cells of Pooideae subfamily is proposed here for the first time, based on vegetation composition and climatic data. We examined 210 topsoil samples from 70 vegetation plots in about 12 plant communities from the Russian Altai mountains to detect differences in the frequencies of occurrence of Crenate sinuate (CRE_SIN) and Crenate lobate (CRE_LOB) submorphotypes. A ratio of the frequencies of these two phytoliths (s/l) is proposed. We clarified the difference between Crenate sinuate and Crenate lobate using morphometry of two target grass species. Crenate lobate has been studied in the leaves of Dactylis glomerata L. Crenate sinuate has been studied in the leaves of Koeleria cristata L. Our study has shown that the frequencies of CRE_SIN, CRE_LOB and s/l ratio depend on the temperature of the coldest and warmest months of the year and the amount of annual precipitation. When counting Crenate as a single morphotype, however, the relationship with climate variables is much weaker. Two submorphotypes have different associations with moisture conditions. Morphometric studies of CRE_SIN and CRE_LOB and data analysis revealed that the most important parameters for separating these two morphotypes are aspect ratio, elongation, convexity and solidity. Distinction between these two morphotypes may aid paleoenvironmental and ecological research in the temperate regions of the world, where Crenate phytoliths of Pooideae are very common.