[Self-healing properties of lateral-root branches of three shrub species after fracture force injure in semi-arid mining area]. / 半干旱矿区3ç§çŒæœ¨ä¾§æ ¹åˆ†æ”¯å¤„æŠ˜åŠ›æŸä¼¤åŽçš„è‡ªä¿®å¤ç‰¹æ€§.

To clarify the sustainable soil reinforcement capacity of the lateral root branches of shrubs after injury by fracture force in a semi-arid coal mining subsidence region of Shendong, we analyzed the ultimate anti-fracture mechanical characteristics of three shrub species, Caragana microphylla, Salix cheilophila, and Hippophae rhamnoides, as well as the self-healing ability of their growth indices and mechanical characteristics after injury by fracture force. The results showed that the anti-fracture force and its strength had significant difference among the three shrub species in their late-ral root branches in the early stage of growing season, with the order of C. microphylla > S. cheilophila > H. rhamnoides. The anti-fracture strengths of C. microphylla and S. cheilophila were positively correlated with the contents of cellulose, lignin and holocellulose, while that of H. rhamnoides was significantly negatively correlated with cellulose and lignin contents, but significantly positively correlated with holocellulose content. The fracture force damage caused by activity in the subsidence area significantly reduced the normal growth and mechanical properties of lateral root branches, which could not return to control levels even after three months of self-healing. For the shrubs, stronger self-healing ability of growth indicators resulted in a higher degree of self-healing of anti-fracture forces. Self-healing ability of growth indicators was in the order of H. rhamnoides (91.2%) > S. cheilophila (82.0%) > C. microphylla (73.9%), and self-healing degree of anti-fracture forces was in the order of H. rhamnoides (41.4%) > S. cheilophila (37.1%) > C. microphylla (30.0%). Sustainable soil reinforcement indices of the shrubs' lateral root branches were in the order of C. microphylla (2.2084) > S. cheilophila (0.2009) > H. rhamnoides (-2.4093). Our results indicated that C. microphylla was the best, S. cheilophila was intermediate, and H. rhamnoides was the least in soil reinforcement in semi-arid coal mining subsidence areas.

[Difference of anti-fracture mechanical characteristics between lateral-root branches and adjacent upper straight roots of four plant species in vigorous growth period].

Taking four plant species, Caragana korshinskii, Salix psammophila, Hippophae rhamnides and Artemisia sphaerocephala, which were 3-4 years old and in vigorous growth period, as test materials, the anti-fracture forces of lateral-root branches and adjacent upper straight roots were measured with the self-made fixture and the instrument of TY 8000. The lateral-root branches were vital and the diameters were 1-4 mm. The results showed that the anti-fracture force and anti-fracture strength of lateral-root branches were lesser than those of the adjacent upper straight roots even though the average diameter of lateral-root branches was greater. The ratios of anti-fracture strength of lateral-root branches to the adjacent upper straight roots were 71.5% for C. korshinskii, 62.9% for S. psammophila, 45.4% for H. rhamnides and 35.4% for A. sphaerocephala. For the four plants, the anti-fracture force positively correlated with the diameter in a power function, while the anti-fracture strength negatively correlated with diameter in a power function. The anti-fracture strengths of lateral-root branches and adjacent upper straight roots for the four species followed the sequence of C. korshinskii (33.66 and 47.06 MPa) > S. psammophila (17.31 and 27.54 MPa) > H. rhamnides (3.97 and 8.75 MPa) > A. sphaerphala (2.18 and 6.15 MPa).

[Species-associated differences in foliage-root coupling soil-reinforcement and anti-erosion].

This paper took four kinds of common soil and water conservation plants of the study area, Caragana microphylla, Salix psammophila, Artemisia sphaerocephala and Hippophae rhamnides at ages of 4 as the research object. Thirteen indicators, i.e., single shrub to reduce wind velocity ration, shelterbelt reducing wind velocity ration, community reducing wind velocity ration, taproot tensile strength, representative root constitutive properties, representative root elasticity modulus, lateral root branch tensile strength, accumulative surface area, root-soil interface sheer strength, interface friction coefficient, accumulative root length, root-soil composite cohesive, root-soil composite equivalent friction angle, reflecting the characteristics of windbreak and roots, were chose to evaluate the differences of foliage-root coupling soil-reinforcement and anti-erosion among four kinds of plants by analytic hierarchy process (AHP) under the condition of spring gale and summer rainstorm, respectively. The results showed the anti-erosion index of foliage-root coupling was in the sequence of S. psammophila (0.841) > C. microphylla (0.454) > A. sphaerocephala (-0.466) > H. rhamnides (-0.829) in spring gale, and C. microphylla (0.841) > S. psammophila (0. 474) > A. sphaerocephala (-0.470) > H. rhamnides (-0.844) in summer rainstorm. S. psammophila could be regarded as one of the most important windbreak and anti-erosion species, while C. microphylla could be the most valuable soil and water conservation plant for the study area.