Extensive exposure of rocks and slopes to natural disasters and human activities has resulted in significant ecological degradation, necessitating the quick and reasonable restoration of the ecological environment in areas affected by rock slopes. Mosses, especially epilithic mosses, have great potential for use in ecological restoration projects in mountainous areas because of their strong endurance and adaptability. The microenvironmental conditions of the rock surface, such as light, moisture, and temperature can affect moss growth and distribution. Individual rocks exhibit diverse surface attitudes that presumably induce variations in microenvironmental conditions, leading to significant variations in the distribution and growth of mosses across different rock faces. In this study, the effects of rock face attitude and microenvironment on the growth and expansion of subalpine epilithic mosses on rock faces were studied at the Jiuzhaigou World Natural Heritage Site in China. The results showed that in a humidity range restrained by natural precipitation, the higher the humidity, the better was the moss growth. The optimum humidity range for epilithic moss was 20 % to 60 %, whereas 20-60 mu mol center dot m- 2 center dot s- 1 was the optimal light intensity. When the temperature exceeded 14 degrees C in the rainy season, mossy growth was better. The inclination of the rock face had a pronounced influence on the water, light, and thermal regimes of the rock surface. Regarding the rock-epilithic moss system in the subalpine area, a chain effect could be identified that the rock surface attitude affects the microenvironment, and the microenvironment further affects the moss growth. The key factors of the three links were inclination of the rock face, humidity, and moss biomass, respectively. As the rock face slopes downward, the microenvironment gradually becomes less conducive to plant growth owing to deteriorating environmental conditions characterised by reduced light intensity, humidity, and temperature.

Soil phosphorus (P) has attracted considerable attention from researchers because of its role in the restoration and stabilization processes of cut slopes in permafrost regions. However, the soil P pool distributions and adsorption-desorption characteristics in alpine cut slopes remain unclear. In this context, we examined in this study the P pools in the aggregates of surface cut soil slopes (0‐10 cm) in areas with three permafrost types, including perennially frozen soil (PF), seasonally frozen ground (SFG), and non-frozen soil (NFS) in the Qinghai-Tibet Plateau, China. In addition, we assessed the P adsorption-desorption characteristics and their correlations with the P pools. The results showed the significant effects of the permafrost types on the contents of total P (TP), available P (AP), labile P (LP), moderately labile P (MLP) and stable P (SP). The inorganic P (IP) contents were higher than those of organic P (OP) in the cut soil slopes of the three permafrost types. In addition, H2O-Pi and NaHCO3-Pi accounted for small proportions of IP, while NaHCO3-Po accounted for the smallest proportion of OP. On the other hand, the SP contents in the soil aggregates were generally higher than those of MLP and LP. In fact, the LP contents in the PF, SFG, and NFS were 72.55, 44.68, and 49.42 mg/kg, respectively. The AP contents in the cut soil slopes of the three permafrost types were significantly correlated with the MLP and LP contents. Moreover, the P adsorption-desorption characteristics of the SFG and NFS were closely related to AP and MLP. Compared with the PF and NFS, the SFG exhibited low and high P adsorption and desorption capacities, respectively. The findings of this study provided an important theoretical basis for the restoration of cut slopes in alpine permafrost regions. © 2024

Soil organic phosphorus (OP) mineralization plays a vital role in the ecological restoration of roadside slopes. However, the changes in the functional bacterial (phoD-harboring) community involved in OP mineralization in soil aggregates during slope restoration are still unknown. In this study, a space-for-time substitution was conducted to compare the differences in the phoD-harboring bacterial community structure and assembly in soil aggregates of four particle sizes (<0.053, 0.25-2, 0.053-0.25, and >2 mm) at different slope restoration ages (7, 11, and 14 years). The results showed no significant differences in the phoD-harboring community diversity and structure among soil aggregates in the same restoration year. Community structure dissimilarity increased with restoration time. Species replacement dominated slope soils restored for 7, 11, and 14 years, accounting for 78.40 %, 79.68 %, and 68.96 % of the total beta-diversity, respectively. Community assembly processes shifted from coexisting deterministic (68 %) and stochastic (32 %) processes in the 7-year restoration slope soil to dominantly deterministic (98 % and 91 %) processes in the 11- and 14-year restoration slope soils, respectively. Dominant phoD-harboring bacteria tended to shift from r-to K-strategies as slope restoration progressed, and the C:P ratio significantly correlated with both community structure and assembly. The increasing C:P ratio over restoration time stimulated phoD-harboring bacteria to secrete alkaline phosphatase to improve P availability, enhancing the complexity and stability of the network. This study elucidates the changing patterns of phoD-harboring bacteria in soil aggregates and provides a theoretical basis for the management of soil P during roadside restoration.

External -soil spray seeding (ESSS) supplies nutrients and water to plants, soils play a pivotal role in the successful rehabilitation of rock -cut slopes. However, few studies have explored how to accurately evaluate the artificial soil quality response to rehabilitation time to determine the effectiveness of the ESSS technique. In this study, taking the rock -cut slopes of Suining Railway Station to study, various soil samples were obtained from 20 -yearold, 13 -year -old and 9 -year -old rehabilitation slopes, where we sampled the surface soil in north- and southfacing slopes, respectively. Fifteen soil indicators were measured as potential indicators of artificial soil quality, and the indicators with significant differences between rehabilitation time considered as a total data set (TDS). Principal component analysis (PCA) and correlation matrix analysis (CMA) were used to determine a minimum data set (MDS), and these indicators within MDS were integrated into a soil quality index (SQI) by standardized scoring functions (SSF) and weighted -additive methods. Results suggested that (1) the SQI was an effective tool for evaluating artificial soil quality, (2) the longer rehabilitation time, the higher artificial soil quality, and (3) the SQI of the north -facing slopes was higher than that of the south -facing slopes in the same rehabilitation years. Nevertheless, all rehabilitation slopes had a low SQI (SQI <= 0.560). Overall, ESSS is a technology that can effectively promote the ecological restoration of rock -cut slopes, but there still exist a room for improvement. In the future ecological reconstruction of rock -cut slopes, more attention should be paid to the restoration of soil quality on the south -facing slopes.

Large-scale road construction has resulted in bare cut slopes in alpine areas, leading to soil erosion and reduced fertility. Soil humus is the basis of soil fertility and an important carbon pool; it is affected by many factors. However, the effects of slope aspect on soil humus on cut slopes are still largely unclear. We studied the differences in the humus content in bulk soil and soil aggregates under four slope aspects (south-facing slope (SFS), west-facing slope (WFS), east-facing slope (EFS), and north-facing slope (NFS)) in alpine areas and analyzed the driving effects of soil physicochemical factors on humus distribution. The contents of fulvic acid carbon (FA-C), humic acid carbon (HA-C), humin carbon (HU-C), humus extractable carbon (HE-C) and total humus carbon (THC) differed among four slope aspects. Humus carbon did not differ among large macro-aggregates (LMA), small macro-aggregates (SMA) and micro-aggregates (MIA). Only the contents of humus carbon in silt + clay fraction (SCA) were significantly lower than those in the other soil aggregates for the NFS and EFS. Soil water content (SWC), soil organic matter (SOM), total nitrogen (TN), and available phosphorus (AP) were important soil physicochemical factors affecting the distribution of humus. Our results suggest a significant effect of slope aspect on the contents of humus carbon, and the silt + clay fraction had a weak ability to retain humus carbon. The study provides a theorical basis for future humus research and soil fertility management of cut slopes in alpine areas.

Phosphorus (P) is the key nutritional element in the soil of cut road slopes undergoing ecological restoration, and the transformation of organic P (Po) is a crucial part of the P cycle. However, the role of phoD-harboring bacteria in driving the mineralization of Po fractions in road slope soil aggregates is unclear. This study analyzed road slope soils that had undergone 7, 11, and 14 years of restoration in the western Sichuan Plateau of China. We examined the differences and associations between the Po fraction content, alkaline phosphatase (ALP) activity, and community composition of rare and abundant phoD-harboring bacteria in soil aggregates of four particle sizes (0.053–0.25, 0.25–2, 0.053–0.25, and, > 2 mm). The results showed that NaHCO3-extracted Po (NaHCO3-Po) content in soil aggregates increased with restoration years, while NaOH-extracted Po (NaOH-Po) content decreased. ALP activity in soil aggregates increased with restoration years, but there was no significant relationship between ALP activity with the phoD-harboring bacterial community. There were significant differences in the composition of rare and abundant phoD-harboring bacterial communities during slope restoration. Soil moisture, pH, organic carbon, and the C:P ratio in soil aggregates were the primary factors affecting the distribution of the Po fractions and the phoD-harboring bacterial community. NaHCO3-Po and NaOH-Po in soil aggregates were likely the main substrates for ALP-mediated Po mineralization. More genera were involved in Po mineralization in slope soils restored for 14 years than in soils restored for 7 and 11 years, and rare phoD-harboring genera were more actively involved in Po mineralization than abundant phoD-harboring genera. This study provides some theoretical basis for P effectiveness enhancement and P management during slope soil restoration. © 2024 John Wiley & Sons Ltd.

Soil phosphorus (P) effectiveness and sustainability play a crucial role in influencing the ecological restoration process of cut slopes. However, the P adsorption-desorption characteristics of soil aggregates during the ecological restoration of cut slopes remain unclear. We selected three roadside slopes that have undergone ecological restoration for 7, 11, and 14 years, respectively, in Songpan County on the eastern Tibetan Plateau in China. We determined the characteristic parameters of P adsorption-desorption in soil aggregates using isothermal adsorption-desorption experiments. X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were conducted to characterize the mineral and functional group properties of soil aggregates. The results showed that the P adsorption-desorption capacity of soil aggregates increased with the restoration years. Microaggregates (0.25 mm). Soil organic matter (SOM), available phosphorus (AP), free iron oxide (FeDCB), and free aluminum oxide (AlDCB) were the driving factor of P adsorption. In addition, total phosphorus (TP), AP, pH, SOM, FeDCB, and AlDCB played key roles in P desorption. SOM, AP, and AlDCB affected indirectly FeDCB, while SOM and TP affected indirectly pH, consequently affecting adsorption-desorption. Calcite was involved in P adsorption by soil aggregates. The ligand exchange between the hydroxyl group in montmorillonite and P in the aqueous phase may the key adsorption-desorption process. The current study provides a scientific basis for promoting the effectiveness and sustainability of soil P in cut slope restoration. © 2024 Elsevier Ltd

The construction of highways and other transportation facilities resulted in a large number of exposed cut slopes, leading not only to the alteration of soil structure but also to phosphorus (P) losses from soils with low utilization rates. These negative effects can result in stunted plant growth and the occurrence of heavy rainfall and earthquakes-associated landslide and mudslide disasters, threatening people's lives. However, few studies have investigated soil aggregates P in cut slopes restored with different methods in the Alpine Mountainous areas of Southwest China. Therefore, three types of cut slopes (cut slopes restored by three-dimensional mesh (TCS), cut slopes restored by galvanized wire mesh (GCS), and cut slopes restored by nature (NCS)) were selected for the study, and the present study aims to assess the total phosphorus (TP), available phosphorus (AP), and P fractions, as well as the P sorption-desorption isotherms in cut slope soil aggregates. The obtained results are as follows: (1) The TP contents in the soil aggregates did not differ significantly between the three types of cut slopes (p > 0.05), In addition, the AP contents and P activation coefficient (PAC) showed significant differences between TCS, GCS, and NCS, while the H2O-Pi, NaHCO3-Po, NaOH-Pi, NaOH-Po, HHCl-Pi, and HHCl-Po contents were significantly different between the three types of cut slopes (p 5 mm; (3) H2O-Pi, NaOH-Pi, and HHCl-Pi were the main P fractions affecting the AP contents in the study area, among which NaOH-Pi exhibited the greatest effect on the AP contents; (4) The lowest P adsorption of soil aggregates was observed in NCS. The maximum P adsorption (Qm) values of the © 2023 Elsevier B.V.

Since natural restoration combined with artificial auxiliary measures may achieve a relatively rapid restoration effect at a lower cost, it has become an essential measure for the ecological restoration of rock slopes. Previous studies have focused heavily on the relationship between substrate nutrients and water conditions and the development of mosses on the rock surface, but quantitative characterization of substantial effect of rock surface texture (e.g., microrelief) on moss growth is absent. The undulating microrelief on the rock surface can increase the heterogeneity of the microhabitat, which may be an important factor affecting the development of moss-dominated biocrusts. In this study, the roughness of rock surfaces, moss coverage and biomass, weight and major nutrient contents of soils within the biocrusts were measured in the western mountainous area of Sichuan Province, Southwest China to further examine the role of rock surface microrelief in the biocrusts. The results showed that three main factors affecting the development of the biocrusts were bryophyte emergence, soil accumulation, and lithology. The presence of moss accelerates soil formation on rock surfaces and lead to the accumulation of nutrients so that all parts of the moss-dominated biocrusts system can develop synergistically. It was found that a microrelief structure with a roughness between 1.5 and 2.5 could gather soil and bryophyte propagules effectively, which may have a strong relationship with the angle of repose. When the roughness is 1.5, the corresponding undulation angle is very close to the theoretical minimum value of the undulation angle calculated according to the relationships between the undulation angle of the protrusion, slope and angle of repose.

The distribution and availability of phosphorus (P) fractions in restored cut slope soil aggregates, along altitude gradients, were analyzed. Samples were collected at 3009, 3347, 3654 and 3980 m of altitude. We examined soil aggregates total phosphorus (TP), available phosphorus (AP) and phosphorus activation coefficient (PAC), and discovered that there was no significant difference in TP levels between all four altitudes samples (p > 0.05). However, there was a significant difference in AP at 3009, 3347 and 3980 m of altitude (p < 0.05). At the altitudes of 3009, 3347 and 3654 m, the AP accumulation in small size aggregates was more advantageous. Overall, PAC dropped steadily as soil aggregates sizes increased, as shown: PAC (3654 m) > PAC (3347 m) > PAC (3009 m) > PAC (3980 m). In all particle size soil aggregates, the distribution of the P fractions was as follows: total inorganic phosphorus (TPi) > total organic phosphorus (TPo) > residual phosphorus (R-P), at 3009, 3347 and 3654 m, but a different registry was observed at 3980 m of altitude: TPo> TPi> R-P. Through correlation and multiple stepwise regression analysis, it was concluded that active NaHCO3-Pi was the main AP source. It was also suggested that more attention should be given to the ratio of small particle size aggregates to increase soil AP storage. In order to improve the activation capacity and supply of soil P, along with promotion of the healthy development of soil ecosystem on slope land, it was suggest that inorganic P fertilizer and P activator could be added to soil at both low (3009 m) and high altitudes (3980 m). (C) Higher Education Press 2023