猫儿山铁杉相邻植株冠层机械磨损对枝叶性状的影响

Canopy mechanical abrasion between adjacent plants influences twig and leaf traits of Tsuga chinensis assemblage in the Mao’er Mountain

机械磨损是邻体植物冠层接壤区域的重要生态过程之一,对枝叶生理和形态特征具有重要影响。但是,当前非常缺乏邻体植物冠层机械磨损对枝叶功能性状影响特征和权衡机制的深入研究。该研究以广西猫儿山的铁杉(Tsuga chinensis)为对象,通过比较邻体冠层间机械磨损区优势枝、劣势枝与非机械磨损区的叶面积、叶长、叶宽、叶厚、比叶面积、叶干物质含量、叶干质量、末端枝含水率和枝直径的差异,分析枝叶功能性状在机械磨损影响下的变异和权衡关系。结果显示:机械磨损显著影响邻体冠层叶干物质含量、比叶面积和叶干质量。具体而言,机械磨损区优势枝叶干物质含量显著大于劣势枝和非机械磨损区,优势枝比叶面积显著低于劣势枝和非机械磨损区,劣势枝叶干质量显著低于优势枝和非机械磨损区。其次,机械磨损对枝叶性状关系的影响格局不同。叶面积-叶长在机械磨损区优势枝、劣势枝和非机械磨损区间表现出一致的正向关系;叶面积-叶宽、叶面积-叶干质量、叶宽-叶厚、叶厚-末端枝直径和叶长-叶宽仅在机械磨损区优势枝显著正相关;叶面积-末端枝直径和末端枝直径-末端枝含水率仅在劣势枝显著负相关;叶干物质含量-叶厚仅在劣势枝显著正相关。其余性状关系在机械磨损区优势枝、劣势枝和非机械磨损区均不显著。以上结果表明,森林植物邻体间的冠层机械磨损可显著改变枝叶功能性状的权衡关系。

Aims Mechanical abrasion is an important ecological process in the adjacent plant canopy bordering area,which can significantly influence the physiological and morphological characteristics of branches and leaves.However,there is a lack of in-depth research on the characteristics and trade-off mechanisms of the mechanical abrasion on neighboring plant canopies in branches and leaves from the perspective of functional traits.Methods This study focused on the Tsuga chinensis from the Mao’er Mountain in Guangxi,China.The leaf area,length,and width,as well as the leaf area of the dominant and inferior branches were compared between adjacent canopy layers in mechanical abrasion zones and nonmechanical abrasion zones.Differences in leaf thickness,specific leaf area,leaf dry matter content and leaf dry mass,terminal twig water content,and twig diameter were also analyzed.Moreover,variation and trade-off relationship between branch and leaf functional traits under the influence of mechanical abrasion were evaluated.Important findings Mechanical abrasion significantly affected the leaf dry matter content,specific leaf area,and leaf dry mass of adjacent canopy leaves.Specifically,the leaf dry matter content of the dominant branches in the mechanical abrasion zone was significantly greater than that in the inferior branches and nonmechanical abrasion zone.Moreover,the specific leaf area of the dominant branches was significantly lower than that of the inferior branches and nonmechanical abrasion areas,whereas the leaf dry mass of the inferior branches was significantly lower than that of the dominant branches and nonmechanical abrasion area.Noteworthy,mechanical abrasion was found to differently influence the relationship between branches and leaves in terms of functional traits.Leaf arealeaf length showed a consistent positive relationship in the mechanical abrasion zone dominant branches,inferior branch,and the nonmechanical abrasion zone.Leaf area-leaf width,leaf area-leaf dry mass,leaf width-leaf thickness,leaf length-leaf width,and leaf thickness-terminal twig diameter were only significantly positively correlated within dominant branches in the mechanical abrasion zone.Leaf area-terminal twig diameter and terminal twig diameter-terminal twig water content were only significantly negatively correlated in the inferior branches.Moreover,leaf dry matter content-leaf thickness was only significantly positively correlated in the inferior branches.Other traits did not show a significant relationship in the dominant branch,inferior branch,and nonmechanical abrasion zone.These results indicate that canopy mechanical abrasion between forest plant neighbors can significantly change the trade-off relationship between branches and leaves regarding to functional traits.