Morphological traits of Bryum argenteum and its response to environmental variation in arid and semi-arid areas of Tibet

As the main part of the Qinghai-Tibet Plateau, Tibet has a large range of elevations. Its complex topography and diverse vegetation types constitute various micro-habitat conditions, which may exert great influence on ecosystems. The bryophytes are higher plant with simple structure, and widely distributed, and extremely sensitive to environmental variation as well. As one of the important indicator plants, its response to environmental variation is important to explore. In this study, to better understand the response of bryophytes to environmental variation, we explored the relationship between the morphological traits of Bryum argenteum and its surrounding climate, topography, soil, and other environmental factors in the arid and semi-arid regions of Tibet. The Bryum argenteum specimens collected in the arid and semi-arid regions of Tibet from 2007 to 2015 were taken for 8 samples each specimen, and slides of plants and leaves were made. The slides were photo graphed and we measured the plant height, leaf length, leaf width, costa length, costa width and hair-point length, and measured the correlations between them and the environmental factors. Our results showed that the morphological characteristics of bryophytes are closely related to environmental variation, among which the hair-point length and plant height showed high coefficient of variation and phenotypic plasticity. The effects of environmental variation on bryophytes are largely different in different substrates. The morphological traits of terricolous Bryum argenteum are largely influenced by growing season precipitation, soil pH, and soil texture, while the morphological traits of saxicolous Bryum argenteum are largely influenced by elevation, growing season temperature, annual precipitation, and total nitrogen, available phosphorus and organic matter in soil. Our study showed the various functional traits of bryophytes are closely related and the combination of these traits collaboratively responds to environmental variation.