The saxicolous moss's features of absorbing water and its structural adaptability in the heterogeneous environment with rock desertification

Bryophytes are a class of pioneer plants at desert vegetation succession and even in extremely dry environments.In this study,a theoretical foundation for the interest of recovering and administering the environments of rock-desertification ecology was provided by compared with the adaptability to habitat heterogeneity in rocky desertification environments among Erythrodontium julaceum,Barbula fallax and Bryum argenteum.The results show that,firstly,E.julaceum and B.fallax are more than B.argenteum in the capacity of holding maximal water and also in the rate of preserving natural water.Secondly,the water-uptaking processes of the three mosses are outer water uptake and inner water uptake.Although the three species had the same dynamic curve of the S type saturated water content,they had considerably different dynamic properties.Little difference was found in the amount of water saturated by E.julaceum and B.fallax.However,the amount of saturated water in E.julaceum and B.fallax were about 2.5 times of that in the silver B.Argenteum.The amount of saturated water and the maximal rates of water uptake,inner as well as outer water uptake in E.julaceum were 3.41,2.52 and 3.02 times than those of B.argenteum,respectively.Similar results were also found in B.fallax.Furthermore,the stem cross-section structure of three mosses showed that B.argenteum and B.fallax had the obvious conducting strand and belonged to endohydric mosses.In contrast,E.julaceum owned no conducting strand and belonged to the part of the ectohydric.Strictly,the structure of endohydric and ectohydric in mosses is not the decisive factor of water absorption capability,which has close relationship with many aspects including growth form,type of capillary system and microstructure of stem and leaf positive correlations.