山西太岳山不同径级油松种内竞争与叶功能性状

The intraspecious competition and leaf functional traits of Pinus tabulaeformis with different diameter classes in Taiyue Mountain,Shanxi Province

为探究不同径级油松的种内竞争与叶功能性状变化规律,以山西太岳山油松人工林为研究对象,将样地中油松按5cm的间隔进行径级划分,并在每个径级中选取3株油松进行叶片取样。测定了不同径级油松的种内竞争强度、比叶面积、叶干物质含量、叶氮含量、叶磷含量及其叶氮磷比。采用单因素方差分析检验不同径级间油松的种内竞争与叶功能性状的差异,并利用Pearson相关性分析油松叶功能性状之间的相关性。结果显示:(1)油松的种内竞争在不同径级间差异明显,种内竞争随径级的增加而减小。(2)油松的胸径与竞争指数二者之间呈幂函数关系(P<0.01)。竞争指数随着对象木胸径增大而逐渐减小,当对象木胸径达到20cm以上时,竞争指数进一步减小并维持在较低水平。(3)面对不同的种内竞争强度,不同径级油松的叶功能性状表现出不同的适应性策略,小径级油松倾向于资源获取型策略,而大径级油松则倾向于资源保守型策略。(4)油松1年生叶与多年生叶的比叶面积与叶干物质含量、叶氮含量与叶氮磷比呈极显著负相关性,叶干物质含量与叶氮含量呈显著正相关性;1年生叶中比叶面积与叶氮含量在呈负相关性,而多年生叶中呈极显著负相关性;1年生叶中叶磷含量与比叶面积、叶氮含量无相关性,叶氮含量与叶氮磷比呈正相关性,而多年生叶呈负相关性、极显著正相关性与无相关性。表明1年生叶与多年生叶叶功能性状之间存在着不同的制约关系。因此在油松人工林管理中,应当充分考虑油松的种内竞争和不同径级的叶功能性状变化规律,为油松人工林的保护与管理提供参考依据。

In order to investigate the dynamics of intraspecific competition and the variations in leaf functional traits across different diameter classes,this study focused on the Pinus tabuliformis plantation located in Taiyue Mountain,Shanxi Province.The diameter classes of P.tabuliformis were categorized at intervals of 5 cm within designated sample plots.From each diameter class,three representative P.tabuliformis individuals were selected for leaf sampling to ensure that our measurements adequately captured the characteristics of each class.We measured several key leaf functional traits,including intraspecific competition intensity,specific leaf area,leaf dry matter content,leaf nitrogen concentration,leaf phosphorus levels,and the ratios of nitrogen to phosphorus in leaves across the differing diameter classes.To analyze the differences in intraspecific competition and the associated leaf functional traits among the various diameter classes,one⁃way ANOVA was employed,while Pearson correlation analysis was utilized to explore the relationships between the leaf functional traits of P.tabuliformis.The results indicated several significant findings:(1)Intraspecific competition for P.tabuliformis exhibited marked differences among the different diameter classes,showing a clear trend where competition intensity decreased as the diameter classes increased.(2)A strong power function relationship was identified between diameter at breast height(DBH)and the competition index of P.tabuliformis,with a statistically significant correlation(P<0.01).Specifically,the competition index exhibited a gradual decline alongside increasing DBH,with a further pronounced reduction that stabilized at a low level once the DBH of the target individuals surpassed 20 cm.This suggests that larger individuals experience less competition,likely due to their established dominance.(3)In response to varying intensities of intraspecific competition,the leaf functional traits demonstrated distinct adaptive strategies across the diameter classes.Smaller⁃diameter P.tabuliformis trees tended to adopt a resource⁃acquisition strategy aimed at maximizing their leaf area and resource uptake,while larger⁃diameter individuals favored a resource⁃conservation strategy that allowed them to maintain their physiological resources.(4)The specific leaf area for both annual and perennial leaves was found to be negatively correlated with leaf dry matter content,leaf nitrogen,and the nitrogen⁃to⁃phosphorus ratio,Furthermore,leaf dry matter content exhibited a positive correlation with leaf nitrogen concentration.Notably,a negative correlation was observed between leaf area and leaf nitrogen in annual leaves,while a highly significant negative correlation was found in perennial leaves.It is worth mentioning that leaf nitrogen was positively correlated with the nitrogen⁃to⁃phosphorus ratio in annual leaves,whereas perennial leaves displayed differing relationships,further underscoring the varied constraints experienced by annual versus perennial leaves.These findings underline the necessity of considering intraspecific competition alongside the changes in leaf functional traits across different diameter classes when managing P.tabuliformis plantations.This comprehensive approach is essential for developing effective protection strategies and management practices that will ultimately enhance the sustainability and productivity of these forest ecosystems.