中文摘要：

选择5个不同纬度的落叶松人工林,比较了落叶松细根（〈2 mm）的直径、根长、比根长和比表面积等形态指标、外生菌根及其侵染率的纬度分异特征,分析了形态特征与主要影响因子间的关系。结果表明：随纬度增加,落叶松1、2级根的外生菌根真菌侵染率降低,菌根颜色变深,分叉减少;细根直径变细,根长缩短,细根比根长和比表面积显著增加;同一地点的细根在不同根序以及侵染与未侵染细根间形态差异明显;冗余分析和回归分析显示,细根直径和根长与年均温、年降水、土壤含水量呈显著正相关,而比根长和比表面积则与土壤全碳、土壤养分含量呈正相关。综上,落叶松细根的形态特征沿纬度梯度呈现出有规律的可塑性响应,外生菌根的宏观形态具有明显的地带性差异,直径和根长主要受气候因子影响,而比根长和比表面积则主要与土壤因子有关。

英文摘要：

We elucidated the changes in larch fine root （diameter 〈2 mm） traits and environ- mental factors in 5 sites across a latitudinal gradient in China, linking the fine root morphological traits （ e. g. mean root length, mean root diameter, specific root surface area （SRA） and specific root length （SRL） with climate and soil factors. Along with the increase in latitude, the mycor-rhizal fungal infection rates of the first and second order roots decreased clearly, the numbers of ectomycorrhizas forks increased and color became darker, and the mean root diameter and root length got smaller, while the SRL and SRA got larger. Furthermore, there was a significant positive correlation between root diameter, length and mean annual precipitation （MAP） , mean annual temperature （MAT） and soil water content. Also, a strong positive correlation was observed between SRL, SRA and soil TC, soil nutrients. The results of our study demonstrated that both ECM and non-infested fine root had clear morphological plasticity across a latitude gradient, and ECM morphological traits varied with site-specific characteristics, and root diameter and root length were mainly affected by climatic factors, whereas SRA and SRL were mainly modified by soil factors.