丝茅入侵对高羊茅根系及土壤性状的影响

针对南方地区丝茅(Imperata koenigii (Retz.) P. Beauv.)入侵对冷季型草坪造成严重危害的实践生产问题,通过模拟高羊茅(Festuca arundiacea L.)草坪建植时丝茅入侵形成的混生群落,连续测定群落中根长密度、根干重密度和根体积密度等根系性状指标,土壤容重、土壤含水量及pH等土壤性状指标,分析丝茅入侵对高羊茅草坪根系及土壤性状影响的动态变化。结果表明:丝茅入侵对高羊茅草坪根长密度、根干重密度和根体积密度均有极显著影响(P<0.01);丝茅入侵60 d起影响根长密度,90 d起影响根干重密度,150 d起影响根体积密度;侵入持续时间对高羊茅根系指标影响排序为根体积密度>根干重密度>根长密度;丝茅对草坪分层土壤的含水量、容重和pH均有极显著影响(P<0.01);入侵60 d起首先影响高羊茅根系主要分布的10~20 cm层的土壤性状,影响逐渐向上、向下扩展;持续时间对土壤性状的影响排序为土壤含水量>容重>pH;丝茅入侵使高羊茅根系分生和更新能力下降,使其根系分布土壤层的含水量降低、透气性变差、酸度增高,从而降低高羊茅根系活性与吸收能力,使其竞争力降低而逐渐退化。本试验结果将为草坪中丝茅的防治提供基础数据。

Dynamic Analysis about Traits of Root and Soil of the Young Festuca arundinacea Turf Infested by Imperata koenigii

Imperata koenigii (Retz.) P. Beauv. (speargrass or cogograss) was rated as the most serious weed in tropical and subtropical areas of world. In this study, I. koenigii and Festuca arundinacea were sowed at the same time to form a mixed community. The root traits, such as the density of root length, root dry weight, root volume, and soil traits, such as soil bulk density, soil water content and pH, in the community were consistently determined at 60, 90, 120, 150, 180, and 210 d after sowing. Dynamic analysis of F. arundinacea root and soil traits showed that infestation of I. koenigii had a significant effect on root length density, root dry weight, root volume density of F. arundinacea (P<0.01). In particular, root length density, root dry weight, and root volume density significantly reduced after 60, 90, and 150 d after sowing, separately. The reduced degrees of F. arundinacea root traits affected by I. koenigii were ranked as root volume density>root dry weight density>root length density. I. koenigii also had a significant effect on soil water content, soil bulk density, pH value in different levels of soil (P<0.01). After sowing 60 d, the soil traits of 10~20 cm layer mainly distributed by F. arundinacea root system were significantly affected by I. koenigii as effects extended upward and downward. The effect of duration time on soil traits was ranked as: soil water content>soil bulk density>pH value. The significantly declining meristematic ability of F. arundinacea root due to the infestation of I. koenigii decreased soil water content, weakened soil permeability and increased acidity. Over all, the infestation of I. koenigii reduced root activity and absorption ability of F. arundinacea.