坡向对野生荩草构件性状和生物量结构及水分配的影响

以3个坡向退化边坡草坪中入侵的野生荩草(Arthraxon hispidus)为研究对象,通过测定叶、茎、根等数量和质量性状、植株生物量累积和分配比及水分含量,分析坡向对荩草构件性状、生物量结构和水分配比的影响,研究荩草对异质生境的生长策略及应对能力。结果表明:1)坡向对光照强度、土壤含水及土层厚度有显著影响(P<0.05),使荩草种群盖度有显著差异。2)坡向对叶、茎及根性状有显著影响(P<0.05),荩草通过调整叶数、分蘖数及根数,改变叶面积、株高、节间长及根长,形成适应坡向生境的构件组成与形状。3)坡向对生物量累积有显著影响(P<0.05),阳坡单株生物量显著大于阴坡和半阴坡,阳坡生物量优先向茎分配,阴坡则向叶分配,通过调整生物量分配比,增加了荩草的适应性和抗逆性。4)坡向对植株含水量有显著影响(P<0.05),阳坡和阴坡植株含水量大于半阴坡,阳坡水分优先向茎分配,阴坡则优先向根分配。综上,荩草可依坡向生境调整生长策略,在3个坡向上形成生长良好的优势种,适合在边坡草坪建植中推广应用。

Effects of slope aspect on component traits,biomass structure and water distribution of Arthraxon hispidus

In the study,wild Arthraxon hispidus invaded into degraded lawn of three slope directions was used as the research object.Indexes including the quantitative and qualitative characters of leaves,stems and roots,the biomass accumulation and distribution ratio and water content of plants were measured.The effects of slope direction on component traits,biomass structure and water distribution ratio of A.hispidu was analyzed.The purpose was to study the growth strategy and coping ability of A.hispidu in the heterogeneous habitats.The results showed that:1)Slope direction had significant effects on light intensity,soil water content and soil thickness(P<0.05),which resulted in significant differences in the coverage of A.hispidu.2)Slope direction had significant effect on the traits of leaf,stem and root(P<0.05).By adjusting the number of leave,tiller and root,A.hispidu changed leaf area,plant height,internode length and root length,which could form components and shapes adapting to the slope habitat.3)Slope direction had a significant effect on biomass accumulation(P<0.05).The biomass per plant on sunny slope was significantly larger than that on shady and semi-shady slopes.The biomass on sunny slope was preferentially distributed to stems,while that on shady slope was distributed to the leaves.The adaptability and stress resistance of A.hispidu were increased by adjusting the distribution ratio of biomass.4)Slope direction had a significant effect on water content of plant.Water content in sunny and shady slopes was greater than that in semi-shady slopes.Water in sunny slopes was preferentially distributed to stems,while that in shady slope was preferentially distributed to roots.In conclusion,the growth strategy of A.hispidu can be adjusted according to the habitat of slope direction.A.hispidu all could form dominant species in three slope directions,which was suitable for popularization and application in planting slope lawn.