马尾松林下套种阔叶树的叶功能性状和化学计量特征季节动态研究

Seasonal Dynamics of Functional and Stoichiometric Characteristics of the Leaves from Broad-Leaved Trees Intercropped Under Pinus massoniana Forest

以马尾松针阔混交复层林中的木荷、火力楠和红锥为研究对象,通过测定各树种在不同季节的叶形态性状和化学性状,探究3种乡土珍贵阔叶树种在马尾松林下叶功能性状和化学计量特征的季节变化规律和资源权衡策略。结果表明:1)各树种叶含水率随季节变化呈降低趋势;叶组织密度、比叶重、叶碳含量随季节变化而升高,春季最低,秋季最高;不同季节的叶片C∶N、C∶P、N∶P差异显著(P<0.05),随季节变化而增大;不同树种之间的叶功能性状和化学计量特征也存在显著差异。2)不同树种之间叶片各指标的相互关系各异,叶功能性状与化学计量特征关系密切。3个树种的叶氮含量、磷含量均与C∶N、C∶P、N∶P显著负相关(P<0.05),叶氮含量与叶磷含量显著正相关(P<0.05)。3)主成分分析结果显示,3个阔叶树种在不同季节的资源权衡策略具有趋同性,随季节变化各树种的资源权衡策略存在由“快速投资-收益型”向“缓慢投资-收益型”转变的趋势。本研究结果可为了解林下套种树种在不同季节的资源权衡策略及对异质性环境的适应机制提供理论参考。

Taking Schima superba,Michelia macclurei and Castanopsis hystrix,three precious local broadleaved tree species in the mixed layer of Pinus massoniana forest as research objects,this study investigated the seasonal changes in leaf morphology and leaf chemical properties and explored resource trade-off strategies.The results showed that 1)The leaf moisture content of each tree species showed a decreasing trend with seasonal changes;the leaf tissue density,specific leaf weight,and leaf carbon content increased with seasonal changes,with the lowest in spring and the highest in autumn.There were significant differences in leaf C/N,C/P,and N/P among different seasons(P<0.05),which increased with seasonal changes.Significant differences were also found in leaf functional traits and stoichiometric characteristics among different tree species.2)The interrelationships between leaf indicators among different tree species were also different,and leaf functional traits were closely related to stoichiometric characteristics.The nitrogen and phosphorus contents in the leaves of the three tree species were significantly and negatively correlated with C/N,C/P,and N/P(P<0.05),while the nitrogen content in the leaves was significantly and positively correlated with the phosphorus content in the leaves(P<0.05).3)The results of principal component analysis showed that the resource trade-off strategies of the three broad-leaved tree species exhibited convergence in different seasons,and there was a trend of changing the resource trade-off strategies of each tree species from a“fast investment return type”to a“slow investment return type”with seasonal changes.The research results provide theoretical reference for understanding the resource balance strategies of understory intercropping tree species in different seasons and their adaptation mechanisms to heterogeneous environments.