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.

Globally, microplastic pollution of soil ecosystems poses a major risk. The early studies found that the impact of microplastics on different plants could vary depending on the type of microplastic, the mass concentration or the plant species. This study investigated the effect of 3 mass concentrations (0.1%, 1%, and 2.5%) and 3 types of microplastics (PE MPs, PLA MPs, and PVC MPs) on adzuki bean biomass, root traits, Chlorophyll content and antioxidant enzymes. According to our findings, all microplastics had an impact on biomass, but PLA MPs had the strongest inhibitory effect. The high mass concentration of microplastics had a significant influence on chlorophyll content. Adzuki beans exhibited varying degrees of damage upon exposure to microplastics, but they were able to withstand the oxidative stress brought on by PE MPs by increasing the activity of antioxidant enzymes (SOD and POD). Comparing the adverse effects of PE MPs on adzuki beans to those of PLA MPs and PVC MPs, principal component analysis and membership function value analysis revealed that the former had fewer impacts. Disparities in the observed effects may be attributed to variations in the properties of microplastics. Subsequent investigations into the mechanisms underlying microplastic toxicity need a more comprehensive exploration.

The runoff infiltration partitioning has direct consequences on preservation of water resources in rural territories, both in agricultural plots and uncultivated areas (e.g. ditches, channels, grass strips), and requires a better understanding of the variability of soil infiltration capacity by disentangling the complex links between soil, vegetation and management. The general objective of the study was to investigate the temporal variation in quasi-steady ponded infiltration rates of a fluvisol soil under bare and different cover crop type (a Malvaceae with a tap-root system and a Poaceae with a fibrous root system) and management conditions (burning, mowing, and chemical weeding) that are commonly found in the Mediterranean vineyards. A modified double-ring infiltration method was used to repeat measurement of the quasi-steady ponded infiltration, fcp, on the same location over time. Placed on a 64 m2 plot area with minimal distances between individual measurements of 30 cm, the setup allowed evaluation of variability among measurements that were conducted within the plot. The results showed a significantly lowerfcp for bare soil than covered soil, and a two-fold higherfcp for soil covered by Malvaceae than Poaceae. A seasonal effect in fcp was observed, with the highest fcp in summer and the lowest in winter. The study revealed a strong spatial variability in fcp along a transect of a few tens of centimeter, and showed no significant effect of management strategies compared to the vegetated control. The results revealed the importance of considering both plant traits and season rather than vegetation management strategies to explain quasi-steady ponded infiltration rates.