Response Of Species Diversity And Functional Traits Of Epilithic Bryophytes To Karst Rocky Desertification Habitat

This study focuses on the epilithic bryophytes in different grades of rocky desertification in Salaxi demonstration area and Nidang Stone forest in Guizhou Province as the research object.The distribution of stony desertification types,topography and landform types,dominant vascular plants and epilithic bryophyte species in the two study areas were investigated,and various meteorological factors were monitored.The species of epilithic bryophytes were identified,and the morphological traits,chlorophyll content,chlorophyll fluorescence parameters and nutrient elements contents of epilithic bryophytes were determined.The functional traits and environmental factors of epilithic bryophytes were analyzed by correlation analysis,linear fitting and quadratic fitting,and the response mechanism of species diversity and functional traits of dominant epilithic bryophytes to the level of rocky desertification was revealed.The main results are as follows:（1）Epilithic bryophytes belong to 70 species and 39 genera of 23families in Salaxi and Nidang,all of which are mosses and there are 17common species in two research areas,43 species in 27 genera and 17families in Salaxi Demonstration area,with the dominant species being Eurohypnum leptothallum,Cyrto hypnum gratum and Gollania tereticaulis,and 44 species in 27 genera and 17 families in the Nidang,Homalothecium leucodonticaule,Meteorium miquelianum and Anomodon minor are dominant.Epilithic bryophytes in the two areas can be divided into 11 geographical floristic components and 4 life types:Turfs,Wefts,Pendants and Fans.（2）The diversity of epilithic bryophytes is various in different rocky desertification habitats.The richness of epilithic bryophyte species in NRD and MRD habitats are higher;The SRD habitat is harsh,on the one hand,it has a strong selectivity for species,on the other hand,the bryophyte community is unstable and its ability to resist external disturbance and restore its own balance is weak.Theβdiversity of the two study areas also indicated that the environmental screening process had a great influence on the composition of the epilithic bryophyte community.（3）Morphological traits of epilithic bryophyte can be used as a good predictor of photosynthetic traits and nutritional traits.The correlation between nutrient traits and leaf shape traits was stronger than that between nutrient traits and stem shape traits.SPAD value,F_o,F_m and NPQ had significant correlation with leaf shape traits,andФ_NO andФ_PSⅡhad strong correlation with stem shape characters.Therefore,nutritional traits and photosynthetic traits which are more complex to determined,can be inferred from morphological traits that are easy to measure.（4）Atmospheric temperature,atmospheric humidity,rock temperature,slope and altitude are the main environmental factors affecting the functional traits of epilithic bryophytes.As the habitat of rocky desertification changes,the functional traits of different types of rocky moss vary,reflecting the differences in genetic characteristics and adaptive strategies of different bryophyte species.With the development of rocky desertification,most epilithic bryophytes shorten plant length,reduce chlorophyll content,light energy conversion efficiency,nutrient utilization efficiency,and increase heat dissipation to adapt to the change of rocky desertification habitat.