菌根类型对亚热带森林主要树种根叶功能性状关联的影响

Effects of mycorrhizal type on the correlation of root and leaf functional traits of main tree species in subtropical forests.

叶片和吸收根(即1级根)是植物地上和地下资源获取器官,研究二者功能性状的关系及其影响因素,有助于深入理解植物生长过程中对资源的利用和分配。本研究在江西省九连山国家自然保护区选择了10种丛枝菌根(AM)树种和8种外生菌根(EM)树种,分析了叶片和吸收根的形态性状(叶厚度、比叶面积、叶组织密度、根直径、比根长、根组织密度)和化学性状(叶与根的碳、氮浓度及碳氮比)在不同菌根类型间的变异及关联。结果表明:与AM树种相比,EM树种的叶片较厚、比叶面积较小,且根直径较细、根组织密度和根碳浓度及碳氮比较低。AM和EM树种的叶片与吸收根的形态性状均不相关,而化学性状(氮浓度和碳氮比)在AM树种中呈正相关,但在EM树种中则不相关。主成分分析结果表明,不管是AM还是EM树种,比叶面积与比根长均呈正交分布,可见叶片与吸收根获取资源具有独立性。此外,根直径与根氮浓度在所有树种和AM树种中均表现出显著正相关,而在EM树种则呈临界负相关。根直径与比根长则是在所有树种和不同菌根类型树种中均呈正相关。总之,本研究的结果强调了菌根类型在调节叶片与吸收根功能性状之间的关系上具有重要性,并建议今后在评估木本植物根系的不同功能性状或根叶功能性状关系时应考虑菌根类型的影响。

Leaves and absorptive roots(i.e.,first-order roots)are resource acquisition organs of above-and belowground for plants.Understanding the relationship between functional traits of leaves and absorptive roots and their influencing factors would be helpful to further understand the utilization and allocation of resources during plant growth.In this study,we measured morphological traits(leaf thickness,specific leaf area,leaf tissue density,root diameter,specific root length,root tissue density)and chemical traits(leaf and root carbon concentration,nitrogen concentration,and carbon to nitrogen ratio)of leaves and absorptive roots for 10 arbuscular mycorrhizal(AM)and 8 ectomycorrhizal(EM)tree species in the Jiulianshan National Nature Reserve in Jiangxi Province.We analyzed the variation and correlation among these functional traits between AM and EM tree species.The results showed that EM tree species had thicker leaves,smaller specific leaf area,finer root diameter,lower root tissue density,lower root carbon concentration and carbon to nitrogen ratio than AM tree species.There was no correlation in morphological traits of leaves and absorptive roots for both AM and EM tree species.There was a positive correlation between leaves and roots in the chemical traits(nitrogen concentration and carbon to nitrogen ratio)for AM tree species,but not for EM tree species.The results of principal component analysis showed specific leaf area and specific root length was orthogonal,regardless of AM or EM tree species,suggesting that leaves and absorptive roots were independent in acquiring resources.In addition,root diameter was positively correlated with root nitrogen concentration among all tree species and among AM tree species,but exhibited a marginally negative correlation among EM tree species.Root diameter was always positively correlated with specific root length among different tree species,regardless of mycorrhizal type.In summary,this study emphasized the importance of mycorrhizal type in shaping the relationship between functional traits of leaves and absorptive roots.Mycorrhizal type should be considered when evaluating multidimensional variation of root traits and different functional trait relationships of leaves and roots for woody plants.