Tibet makes up the majority of the Qinghai-Tibet Plateau, often referred to as the roof of the world. Its complex landforms, physiognomy, and climate create a special heterogeneous environment for mosses. Each moss species inhabits its own habitat and ecological niche. This, in combination with its sensitivity to environmental change, makes moss species distribution a useful indicator of vegetation alteration and climate change. This study aimed to characterize the diversity and distribution of Didymodon (Pottiaceae) in Tibet, and model the potential distribution of its species. A total of 221 sample plots, each with a size of 10 × 10 m and located at different altitudes, were investigated across all vegetation types. Of these, the 181 plots in which Didymodon species were found were used to conduct analyses and modeling. Three noteworthy results were obtained. First, a total of 22 species of Didymodon were identified. Among these, Didymodon rigidulus var. subulatus had not previously been recorded in China, and Didymodon constrictus var. constrictus was the dominant species. Second, analysis of the relationships between species distributions and environmental factors using canonical correspondence analysis revealed that vegetation cover and altitude were the main factors affecting the distribution of Didymodon in Tibet. Third, based on the environmental factors of bioclimate, topography and vegetation, the distribution of Didymodon was predicted throughout Tibet at a spatial resolution of 1 km, using the presence-only MaxEnt model. Climatic variables were the key factors in the model. We conclude that the environment plays a significant role in moss diversity and distribution. Based on our research findings, we recommend that future studies should focus on the impacts of climate change on the distribution and conservation of Didymodon.

The bryophyte flora of Helan Mountain (China, Inner Mongolia Province) is studied and analyzed. It includes 201 taxa (10 Hepaticae and 191 Musci, including subspecies and varieties) from 77 genera and 30 families. Most of species have a broad North Temperate distribution. With the increase of altitudes and the variation of habitats, the distribution of bryophytes on Helan Mt. shows a clear vertical zonation. Based on our observation, we have classified the zonation of bryophytes in Helan Mountain into 5 altitudinal belts. РезюмеИзучена и проанализирована бриофлора горы Хелан (Китай, провинция Внутренняя Монголия). Она включает 201 таксон (10 печеночников и 191 мох, в том числе несколько подвидов и разновидностей) из 77 родов и 30 семейств. Большинство видов имеет широкое распространение в умеренной зоне Северного полушария. По мере повышения абсолютной высоты на горе Хелан возрастает разнообразие местообитаний, формирующее выраженную вертикальную поясность; по мохообразным можно выделить до пяти поясов.

Both papillae and mammillae are important structural characteristics for Pottiaceae classification, but these characters are diverse and their nomenclature is confused, hindering the classification of Pottiaceae. So, we selected representative species that cover all types of papillae and mammillae of Chinese Pottiaceae and observed and compared differences between them using light and scanning electronic microscopy. We corrected the chaotic descriptions of papillae of representative species, and have provided a uniform set of terms (“simple”, “forked”, “branched”, and “pedicellate”) to describe the shapes of papillae. In addition, we described how to quickly and accurately use papillae and mammillae to classify representative species in Chinese Pottiaceae.

Soil microbiotic crusts cover extensive portions of the arid and semiarid regions of the world and play an important ecological role. Moss is one of the major components in the crusts. The reproduction and establishment of the mosses are crucial to the formation of moss crusts. Bryum argenteum is the dominant species of moss crusts in the Shapotou region (104°57′E, 37°27′N) of the Tengger Desert. In search for the characteristics of natural reproduction and establishment of the mosses, 10 quadrates (10×10 cm for each) were obtained by removing the moss crusts in different positions of fixed dunes. These 10 quadrates were observed for 3 years depending on the species' components and coverage. Meanwhile, in the third year, two quadrates (1×1 m for each) were set up in a crustabsent area and two different experiments of the asexual reproduction (broadcast planting and offshoots) were conducted, respectively. The reproductive process was observed under the microscope, and the morphological indicators of the new individuals were measured. The results were compared with the ones from indoor experiments using the same methods. All the results showed the following: (1) 70% of the quadrates (i.e., 7 of the 10 quadrates) were recovered within 3-4 years; thus, the quick recovery might be due to the dispersal and reproduction of the fragments of stems and leaves of B. argenteum; (2) as for the two quadrates in the artificial reproduction test, the new plants occupied the uncovered space of the quadrates in 1 month, and there were two main reproduction approaches, one of which was that the stems continually branched and produced young plants, and the other was that the young plants and the fragments of the stems and leaves repeatedly and extensively reproduced protonema, which finally developed into a large number of new plants; (3) the reproductive characteristics were identical, though the protonema in the field was more robust and had more branches than the ones indoors.

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