Soil erosion can be effectively controlled through vegetation restoration. Specifically, roots combine with soil to form a root-soil complex, which can effectively enhance soil shear strength and play a crucial role in soil reinforcement. However, the relationship between root mechanical traits and chemical compositions and shear performance and reinforcing capacity of soil is still inadequate. In this study, we determined the root chemical properties, performed root tensile tests and root-soil composite triaxial tests using two plants-one with a fibrous root system (ryegrass, Lolium perenne L.) and the other with a tap root system (alfalfa, Medicago sativa L.)-and calculated the factor of safety (FOS). The results revealed that the relationship between root diameter and tensile strength differed among different root characters. Holocellulose content and cellulose content were the main factors controlling the root tensile strength of ryegrass and alfalfa, respectively. The shear properties of the root-soil complex (cohesion (c) and internal friction angle (phi)) are correlated with soil water content (SWC) and root mass density (RMD). Root traits had a more substantial effect on c than phi, with significant differences in c between ryegrass and alfalfa at 7 % and 11 % SWC. The root-soil complex had an optimum RMD, and the maximum increase rates of c were 80.57 % and 34.4 %, respectively. Along slopes, sliding first occurs at the foot of the slope, thus demanding emphasis on protection and reinforcement. On steep gradients with low SWC, ryegrass strongly contributes to soil reinforcement, whereas alfalfa is more effective on gentle gradients with high SWC. The results provide scientific references for species selection for vegetation restoration in the Loess Plateau and a deeper understanding of the mechanical mechanism of soil reinforcement by roots.
Plant roots improve the stability of collapsing walls and prevent their collapse; they are thus important for controlling the degree of Benggang erosion in southern China. The vegetation species on the collapsing walls are diverse, and the interaction of the root systems with soil affects the stability of the collapsing walls. Most recent studies have only examined the effects of single plants. In order to investigate the effects of the roots of different vegetation types on the shear strength of soil in collapsing walls and their interaction mechanisms of action, this study was conducted using the roots of the herb Dicranopteris dichotoma and the shrub Melastoma candidum. A direct shear test of indoor remodeled soil was carried out by varying water content (15%, 25%) and herb to shrub root ratio (100:0, 75:25, 50:50, 25:75, and 0:100). The results showed that the shear strength (96.09 kPa) and cohesion (49.26 kPa) of root-containing soil were significantly higher than plain soil (91.77 kPa, 42.17 kPa), and the highest values were obtained when herb to shrub root ratio was 100:0 (113.27 kPa, 62.85 kPa). Here, tensile tests and scanning electron microscopy revealed that the tensile force and tensile strength of the roots of Dicranopteris dichotoma were weaker but effective for maintaining soil stability because of their abundance roots, which could achieve a stronger bond to soil. Simultaneously, herbaceous roots have a small diameter, the Root Area Ratio (RAR) of the roots is larger under the same mass condition, which can better contact with soil and the mechanical properties of roots are fully utilized. Therefore, the soil shear strength is higher and can better resist external damage when herbaceous roots accounts for a larger proportion. The results of this research have implications for the selection and allocation of ecological measures for prevention and control of Benggang.
Revegetation following human-induced damage to vegetation is now a common phenomenon in many ecologically fragile areas around the globe. However, more attention has been paid to climate and ecological engineering factors as influences on the effectiveness of vegetation restoration, while the extent to which socioeconomic factors influence vegetation restoration remains a question that has not been clearly answered. In this study, socio-economic data were obtained through field and household surveys, and then the extent to which socio-economic factors influence the effects of vegetation restoration and their mechanisms of action were assessed using a generalized linear mixed effects model, a partial least squares variable projection significant indicator approach, and a partial least squares path modeling approach. It was found that among the socioeconomic factors, variables such as percentage of cars, conservation awareness, and agricultural practices significantly influenced vegetation restoration (the R2 values are 0.21, 0.15 and 0.15). In terms of importance analysis, economic factors ranked first in terms of importance, followed by psychological factors, agricultural system factors, cultural factors, and natural factors in that order. From the comprehensive impact analysis, economic factors, cultural factors, and agricultural system factors positively affect vegetation recovery (the path coefficients are 0.26, 0.06 and 0.08), and psychological factors negatively affect vegetation recovery (the path coefficient is -0.31). To summarize, in addition to ecological engineering, the remaining socio-economic factors are also important and cannot be ignored for their influence on the effectiveness of vegetation restoration.
Ecological restoration of abandoned mining areas in arid regions presents significant challenges, especially in terms of soil salinization, vegetation loss, and limited water resources. In the Hami arid area of Xinjiang, vegetation restoration is crucial for stabilizing ecosystems and combating land degradation. This study investigated the effects of two irrigation methods-drip and border irrigation-on the growth and survival of four plant species: Tamarix chinensis, Calligonum mongolicum, Haloxylon ammodendron, and Phragmites australis, each exposed to salinity levels of 8 g/L, 12 g/L, and 16 g/L. Our results showed that drip irrigation significantly improved the growth and survival outcomes for most species, particularly T. chinensis and H. ammodendron, with average heights, crown sizes, and base diameters substantially higher under drip irrigation compared to border irrigation (p < 0.05). C. mongolicum, however, displayed optimal vertical growth under border irrigation, although drip irrigation promoted a denser, more compact crown structure. Salinity tolerance varied by species, with 8 g/L salinity being optimal for all, while higher salinity levels (12 g/L and 16 g/L) reduced growth across species, underscoring the importance of salinity management in restoration efforts. P. australis, assessed only under border irrigation due to its high water requirements, showed stable growth but reduced tolerance at higher salinities. These findings highlight that drip irrigation, particularly when combined with moderate salinity (8 g/L), is a more effective strategy for enhancing vegetation growth and survival in arid, saline environments. Our study provides practical recommendations for irrigation and salinity management in ecological restoration, offering insights for improving vegetation resilience in arid mining landscapes.
The Bulianta Coal Mine is among the problematic coal mining areas in China that is still creating environmental damage, especially associated with soil destruction. Therefore, a scientific investigation was conducted to establish a scientific basis for evaluating the impact of planted forest on soil physical and chemical properties, as well as the ecological benefits following 15 years of vegetation restoration in the area. The soil physicochemical characteristics and distribution of organic carbon storage in the 0-80 cm layer soils of Pinus sylvestris forests, Prunus sibirica forests, and Hippophae rhamnoides forests restored after 5, 10, and 15 years were investigated. The immersion method was used to determine soil porosity and density followed by the determination of soil indicators, and a statistical ANOVA test was applied to examine the differential effects of different vegetation types and restoration years on soil properties. The results clearly demonstrated the following: (1) The recovery of vegetation was achieved after a period of 15 years, with the average bulk density of the 0-80 cm soil layer as follows: P. sylvestris forest (1.513 gcm-3) > P. sibirica forest (1.272 gcm-3) > H. rhamnoides forest (1.224 gcm-3), and the differences among different forest types were statistically significant (p P. sibirica forest (44.56 thm-2) > H. rhamnoides forest (41.87 thm-2). In summary, during the ecological vegetation restoration process in the Bulianta Core Mine, both P. sylvestris forest and P. sibirica forest exhibit superior carbon storage capacities compared to H. rhamnoides forest, as well as more effective soil improvement outcomes.
Lucerne (Medicago sativa L.) is one of the most successfully introduced species for revegetation on the Loess Plateau of China and provides important ecosystem services. However, the driving mechanism of soil organic carbon (SOC) and total nitrogen (TN) in lucerne grasslands remains unclear. This study explored the controlling factors of SOC and TN in lucerne grasslands in the semiarid Loess Plateau. A total of 112 quadrats were employed in 28 lucerne fields. Vegetation characteristics, topographic factors, and soil properties at a 0-20 cm depth were measured in each quadrat. The SOC and TN contents increased with altitude and showed positive correlations with species richness, aboveground biomass of native plants, soil moisture, soil inorganic nitrogen, total soil phosphorus (P), and C:P and N:P ratios. Variations in SOC and TN contents were mainly attributed to soil resources, followed by the interaction of topography, vegetation and soil. Soil P, soil moisture, altitude, and native plant species were the main factors controlling SOC and TN contents in these lucerne grasslands. Results suggest that specific abiotic (soil P and moisture) and biotic (plant species diversity) factors controlled SOC and TN in semiarid lucerne grasslands. These factors should be included in SOC and TN evaluation models to predict the future terrestrial ecosystem carbon and nitrogen dynamics.