阔叶红松林3种典型蕨类叶功能性状的垂直变异

Vertical variations in leaf functional traits of three typical ferns in mixed broadleaved-Korean pine forest

研究蕨类在不同垂直高度下叶功能性状及其相关关系的差异,可为揭示大型蕨类叶片的资源利用策略提供科学依据。以阔叶红松(Pinus koraiensis)林内的粗茎鳞毛蕨(Dryopteris crassirhizoma)、东北蹄盖蕨(Athyrium brevifrons)和荚果蕨(Matteuccia struthiopteris)3种蕨类为研究对象,将个体按叶片垂直高度分为上、中、下3层,分别测定其比叶面积、叶干物质含量、净光合速率、瞬时水分利用效率、叶氮含量和叶磷含量,并测定每株个体的光环境和土壤因子,重点揭示叶功能性状的垂直变异规律及相关关系。结果表明:(1)3种蕨类叶干物质含量随叶片垂直高度增加均呈递增趋势,比叶面积无显著差异;东北蹄盖蕨和荚果蕨净光合速率随叶片垂直高度增加呈递增趋势;荚果蕨瞬时水分利用效率随叶片垂直高度增加先增后减,叶氮含量逐渐减少;粗茎鳞毛蕨叶磷含量随叶片垂直高度增加表现为先增后减。(2)叶氮含量与比叶面积,瞬时水分利用效率与净光合速率显著正相关;叶氮含量与叶干物质含量,叶干物质含量与比叶面积则显著负相关;上述叶功能性状间的相关关系在不同垂直高度间均无显著差异。(3)土壤有效磷含量和土壤pH是不同垂直高度叶功能性状变异的主要影响因子,土壤有效磷含量对叶功能性状变异的解释度最高。该研究表明,阔叶红松林内大型蕨类的叶功能性状存在一定的垂直差异,然而个体内部性状间的变化速率基本恒定,光环境和土壤因子对不同垂直高度叶功能性状变异的影响程度不同。

Aims Understanding the differences in leaf functional traits and their correlations in ferns at different vertical heights can provide a scientific basis for revealing the resource utilization strategies of large fern fronds.Methods Individuals of three fern species in a mixed broadleaved-Korean pine(Pinus koraiensis)forest,i.e.,Dryopteris crassirhizoma,Athyrium brevifrons and Matteuccia struthiopteris were divided into upper,middle,and lower layers according to the vertical height of leaves.We measured specific leaf area,leaf dry matter content,net photosynthetic rate,instantaneous water use efficiency,leaf nitrogen content and leaf phosphorus content,as well as the light environment and soil factors of each individual plant to reveal the vertical variation patterns and correlations of leaf functional traits.Important findings(1)Leaf dry matter content of the three fern species increased with the vertical height of the fronds,but specific leaf area showed no variation.The net photosynthetic rate of A.brevifrons and M.struthiopteris showed an increasing trend with the increases of vertical height of fronds,the instantaneous water use efficiency of M.struthiopteris increased and then decreased with the vertical height of the fronds,and leaf nitrogen content gradually decreased;leaf phosphorus content of D.crassirhizoma showed an increase and then decreased trend.(2)There were positive correlations between leaf nitrogen content and specific leaf area,and also between instantaneous water use efficiency and net photosynthetic rate.There were negative correlations between leaf nitrogen content and leaf dry matter content,and between leaf dry matter content and specific leaf area.The correlations among those leaf functional traits did not differ significantly among different vertical heights.(3)Soil available phosphorus content and soil pH were the main factors affecting the variation of leaf functional traits at different vertical heights,with soil available phosphorus content having the highest explanatory degree to the variation of leaf functional traits.Our results indicated that there were vertical differences in leaf functional traits of large ferns in the mixed broadleaved-Korean pine forest,but the rate of change among individual characters was basically constant,the effects of light environment and soil factors on the variation of leaf functional traits differed among vertical heights.This study provided reference for further research on the mechanism of leaf functional traits variation in different vertical heights of ferns in understory.