Rocky desertification is the most serious ecological disaster in karst areas. Comprehensive control of rocky desertification plays an important role in promoting the economic development of karst areas. Studying the stoichiometric characteristics of mosses and soil can provide a powerful reference for the ecological restoration and evaluation of ecosystems experiencing rocky desertification. Soil and mosses were collected from sites representing different stages of ecological restoration (bare rock, grassland, shrubland, and secondary forest), and the contents of carbon (C), nitrogen (N), and phosphorus (P) were detected for ecological stoichiometric analysis. The results indicate that in different restoration stages following karst rocky desertification, the contents of soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) and the stoichiometric ratios in the shrub habitat are higher than those in the bare rock, grassland, and secondary forest habitats. However, the TP and available P contents were low at all stages (0.06 g/kg and 0.62 mg/kg, respectively). The N and P contents and stoichiometric ratios in the mosses showed no significant differences among the succession stages. The C contents in the mosses had a significant positive correlation with SOC and TN and TP content, and the P content had a significant positive correlation with the soil available P. However, there was a significant negative correlation between the C: N and C:P ratios of the bryophytes and soil C: N. In summary, during the process of natural restoration of karst rocky desertification areas, SOC and soil TN contents accumulate with each succession stage. Soil nutrients are higher in shrub habitats than in other succession stages. Mosses have a strong effect on improving soil nutrients in rocky desertification areas.

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Background Lithophytic bryophytes grow on the rock surface, change the habitat on the rock surface through biological karstification, and provide a material basis for the growth of other plants. However, the surface calcium content of bare rock is high. The lithophytic bryophytes may have a special mechanism to adapt to the karst high calcium environment. The present study aimed to explore the physiological regulation process of karst lithophytic bryophytes under high calcium environment, and to provide scientific basis for revealing the maintenance mechanism of karst biodiversity. Results With the increase of Ca2+ concentration, the contents of Pro, SP and MDA of lithophytic bryophytes showed a downward—upward—downward trend. However, when Ca2+ ≥ 400 mmol/L, the contents of Pro and SP changed significantly at 1d, 2d, 3d, 5d and 7d with the extension of culture time, and lithophytic bryophytes died after 2 months of culture. Under different Ca2+ concentrations, the maximum SOD activity of lithophytic bryophytes is 1758.00 (U/g FW), the minimum is 92.60 (U/g FW), the maximum POD activity is 120.88 (U/g FW), and the minimum is 4.80 (U/g FW). The antioxidative activity of of Hyophila involuta are higher than that of Didymodon constrictus and Eurohypnum leptothallum, and its enzyme activity changed significantly with the increase of calcium concentration and time.At the same time, the contents of TChl, Chla, and Chlb in lithophytic bryophytes decreased with the increase of Ca2+ concentration. When Ca2+ = 400 mmol/L, the contents of TChl and Chla were the lowest, but when Ca2+ > 400 mmol/L, they began to increase. In addition, ABA is negatively correlated with TChl and Chla, and positively correlated with ROS. It shows that ABA has a certain role in regulating the adaptation of lithophytic bryophytes to high calcium environment. Conclusions Lithophytic bryophytes have strong calcium tolerance, and their physiological response to high calcium stress is different from vascular bundle plants. The general stress principle is not applicable to lithophytic bryophytes. The response of lithophytic bryophytes to the change of Ca2+concentration is slow, showing passive response or inert response.

Background Bryophytes have an important ecological function in maintaining ecological diversity, material transformation, and energy cycles in ecosystems. In this study, bryophytes in a typical karst area were the research objects. The coverage and abundance of rocky bryophytes in established plots were recorded. The composition and distribution characteristics of the karst epilithic mosses were analyzed by importance values, a dissimilarity index and ggplot2 in R. Results The karst epilithic moss communities included 207 species in 93 genera and 37 families, including 185 species in 27 families and 80 genera of mosses and 22 species in 10 families and 13 genera of liverworts. The dominant families were Pottiaceae, Brachytheciaceae, Thuidiaceae, Bryaceae, Hypnaceae, Mniaceae, Entodontaceae, and Lichenaceae. The dominant species were Thuidium kanedae, Pseudosymblepharis angustata, Trichostomum involutum, Racopilum cuspidigerum, Brachythecium helminthocladum, Eurohypnum leptothallum, Hyophila involuta, Anomodon rugelii, Taxiphyllum taxirameum, and Bryohaplocladium angustifolium. Epilithic mosses in karst habitats have five life forms: turf, weft, cushion, slanting, and pendant. The main life forms we observed were turf and weft. Conclusions The distribution of the epilithic moss communities is closely related to their habitats. The diversity of bryophytes in areas with high forest coverage, high humidity, and abundant water and heat conditions is higher than that of bryophytes in rocky desertification habitats.