Search Results (5)

Bamboo is widely distributed throughout the world, particularly in tropical and subtropical regions. This study aims to investigate the biomechanical properties of the root system of Bambusa pachinensis (Pachi bamboo). The root system of Pachi bamboo grows densely in clusters, with most roots growing vertically and potentially penetrating more than one meter into the soil after growing for several years. Owing to these characteristics, Pachi bamboo is considered a promising plant species for soil reinforcement. However, research on its root reinforcement capabilities remains limited. In situ shear and pullout tests were conducted to assess the root reinforcement of the fibrous root system. The root diameters of Pachi bamboo are typically less than 4 mm, and its tensile strength is notably lower than that of tree roots. This study establishes a method for estimating the root reinforcement of Pachi bamboo based on the number and cross-sectional area of the culms in a single bamboo cluster. The relationship between the maximum tensile force (F_ult) and root diameter (D) is F_ult = (3.65)D^2.59, where F_ult is in Newtons (N), and D is in millimeters (mm). The relationship between the pullout resistance (P_ult) and the shear resistance (S_ult) with the number of culms (SN) is P_ult = 46.5(SN) and S_ult = 0.53(SN) + 5, where P_ult is in Newtons (N), and S_ult is in kilopascals (kPa). These results suggest a positive contribution of the number of culms to mechanical resistance. Full article

Plants play a crucial role in soil fixation and enhancement of slope stability, and saline–alkaline stress is one of the main restrictions inhibiting plant growth and development. At present, there is a lack of research on the effects of saline–alkaline composite stress on the mechanical properties of the root system and the erosion resistance of the root–soil complex. In this study, three gradients of saline–alkaline composite stress treatments and a control of saline-free treatment was set up for Oenothera biennis, Perilla frutescens, Echinops sphaerocephalus, and Lychnis fulgens. The plant salt damage rate, osmotic index, antioxidant enzyme activity and plant root morphological indicators were measured. The biomechanical characteristics were determined by stretching tests, the resistance of the plant was measured by a whole-plant vertical uprooting test, and the anti-erosion capacity of the root soil composite was measured by scrubbing test. The results showed that, at 200 mM, the salt damage index and salt damage rate of the four plants, in descending order, were as follows: E. sphaerocephalus < L. fulgens < O. biennis < P. frutescens. Among them, SOD of Perilla frutescens did not play an obvious protective role, and the substantial changes in CAT and POD, as well as the content of soluble sugars, soluble proteins, and proline, showed its sensitivity to saline and alkaline stresses. Root growth was also significantly suppressed in all four plants, the 100- and 200-mM concentrations of saline solution significantly reduced the average tensile strength of O. biennis and P. frutescens, while the saline–alkali solution of 200 mM significantly reduced the elongation of E. sphaerocephalus and L. fulgens, and significantly elevated the soil detachment rate of the root–soil composite for E. sphaerocephalus. Additionally, all three concentrations of saline treatments significantly reduced the pullout resistance of all 4 plants. There was a negative power rate relationship between tensile resistance and root diameter in four plant species, while the relationship between tensile strength and root diameter showed a negative power law only for L. fulgens treated with 0–50 mM saline solution. There was no significant correlation between elongation and root diameter in the four plants. P. frutescens had the greatest tensile resistance and strength, as well as the lowest rate of elongation, while L. fulgens possessed the greatest pullout resistance, and both had comparable resistance to erosion of the root–soil complex. Therefore, compared to the other three plants, L. fulgens is more suitable for soil reinforcement applications on saline slopes. Full article

To investigate the sensitivity and significance of different morphological characteristics of plant root systems on vertical pullout resistance, this study considered four main influencing factors: the number of lateral roots, taproot length, the branching angle of the lateral root, and the unit weight of the soil around the root. PC plastic model roots were employed to conduct a vertical pullout orthogonal experiment. A comprehensive ${\mu }_X$ theoretical analysis method based on the whole root system pullout test was applied for a stress analysis on root segments. Based on the results, the factors affected the vertical pullout resistance of plant root systems in the order of number of lateral roots > taproot length > unit weight of soil around the root > branching angle of the lateral root. When the number of lateral roots increased from 2 to 3, the vertical pullout resistance increased by 64%. Also, when the taproot length increased from 50 to 60 cm, the vertical pullout resistance increased by up to 46%. Furthermore, the unit weight of soil around the roots had a positive linear correlation with vertical pullout resistance. Based on the results, the number of lateral roots and the taproot length were the primary factors affecting the magnitude of the root system’s vertical pullout resistance. When selecting plants for slope protection, plant types with a larger number of lateral roots and longer taproots should be considered as the two most significant factors for achieving a better slope protection methodology. Full article

In southern Taiwan, mudstone badland accounts for over 1000 km² of the upstream region of watersheds. Rainstorms often induce interrill and surface erosion on the mudstone slopes. Furthermore, the large quantity of soils detached by surface runoff result in severe sedimentation in reservoirs. Thus, soil erosion control of mudstone badlands represents one of the most pressing problems in reservoir watershed management. Cynodon dactylon (L.) Pers. (Bermuda grass) and Eremochloa ophiuroides (Munro) Hack. (Centipedegrass) are two native predominant C₄ grass species appearing on mudstone badlands. They play a key role in erosion control and the revegetation of mudstone slopes. Nevertheless, their root functional traits and water erosion-reducing potential have not been investigated. In this study, the root traits were examined. Vertical pullout and tensile tests were conducted to measure root pullout resistance and root tensile strength. Hydraulic flume tests were also performed to evaluate their water erosion-reducing potentials. The results demonstrated that the root systems of C. dactylon and E. ophiuroides grasses all belonged to the fibrous M-type. C. dactylon had remarkably better root traits compared to those of E. ophiuroides. Furthermore, the root tensile resistance of C. dactylon was remarkably higher than that of E. ophiuroides. In addition, hydraulic flume tests showed that C. dactylon has remarkably smaller soil detachment rates than that of E. ophiuroides. Altogether, our data clearly show that C. dactylon has better root traits, root pullout resistance, root tensile resistance and water erosion-reducing potential than E. ophiuroides and is more suitable for erosion control of mudstone badland. Further studies on large-scale implementation techniques of these species for efficient vegetation restoration are needed. Full article

In southern Taiwan, rivers sporadically cease to flow and dry up in winter. The exposed dry riverbeds are very vulnerable to wind erosion. The strong northeast monsoon often induces serious estuarine sand drift and fugitive dust, which cause damages to agricultural crops, human health and infrastructures. Giant reed (Arundo formosana), common reed (Phragmite australis) and the wild sugarcane (Saccharum spontaneum) are pioneer grass species in estuary areas. They have great potential to reduce wind erosion and control windblown dust on agricultural lands. Nevertheless, their root traits, biomechanical characteristics and wind erosion resistance have not been investigated. In this research, the root traits were investigated utilizing the hand digging technique and the WinRHIZOPro System. Root pullout resistance and root tensile strength were estimated using vertical pullout and root tensile tests. Wind tunnel tests were executed to evaluate the wind erosion resistance using six-month-old plants. The results demonstrated that the growth performance and root functional traits of S. spontaneum are superior to those of A. formosana and P. australis. Additionally, the root anchorage ability and root tensile strength of S. spontaneum plants are notably greater than those of A. formosana and P. australis plants. Furthermore, the results of the wind tunnel tests showed that the wind erosion resistance of A. formosana is remarkably higher than those of S. spontaneum and P. australis. This study demonstrates that A. formosana and S. spontaneum are superior to P. australis, considering root traits, root anchorage ability, root tensile strength and wind erosion resistance. Taken together, our results suggest that S. spontaneum and P. australis are favorable for riverbed planting, while A.formosana is applicable for riverbank planting in estuary areas. These results, together with data on the acclimation of estuarine grasses in waterlogged soils and brackish waters, provide vital information for designing planting strategies of estuary grasses for the ecological engineering of estuarine sand drift control. Full article