毛乌素沙南缘紫穗槐根系垂直分布特征

采用全株挖掘法对毛乌素沙南缘不同年限种植的紫穗槐进行取样,研究60龄、35龄、28龄、6龄地上部形态特征、土壤含水量、根系生物量、比根长、根比例、根体积、根表面积及根长密度的垂直分布格局,以期揭示紫穗槐在沙地生境下生态适应性。结果表明,随着土壤深度的增加,各株龄紫穗槐根生物量、根体积,根表面积均呈指数Y=ae^-bx形式递减;通过对消弱系数的分析,根系集中分布于接近地表的土层中,根系分布各参数之间表现不同程度的相关性,土壤含水量(SM)与地上生物量(AGB)、根生物量(RB)、比根长(SRL)的相关性达显著水平,与根表面积(RSA)呈正相关。利用主成分分析法将根系分布参数确定为水分控制因子和构架因子。随着株龄的增加紫穗槐没有出现衰退现象,其根系有自疏与更新的能力,不断适应环境的变化。

Vertical root distribution characteristics of Amorpha fruticosa on southern Mu Us Sandy Land

60-year, 35-year, 28-year and 6-year old Amorpha fruticosa growing on southern Mu Us Sandy Land were sampled using the total strain mining method. Aboveground morphological characteristics, soil moisture, root biomass, specific root length, root fraction, root volume, root surface area and root length density were studied to reveal the ecological adaptability of A. fruticosa in a sandy habitat. Results indicated that with increasing soil depth, the root biomass, root volume and root surface area of A. fruticosa of all ages declined exponentially in the form Y=ae^-bx. Root extinction coefficient analysis showed that roots were concentrated close to the soil surface. Parameters of root distribution showed different degrees of correlation: Soil moisture was significantly correlated with above ground biomass, root biomass, and specific root length. Soil moisture was also positively related to root surface area. The root distribution parameters, moisture control factor and framework factor, were confirmed by principal component analysis. With increasing years, A. fruticosa did not show an aging phenomenon since its roots had the ability to self-thin and update constantly, adapting to the changes in the environment.