发育阶段和海拔对岷江源区陇蜀杜鹃小枝功能性状及生物量分配的影响

Effects of growth stage and altitude on twig functional traits and biomass allocation of Rhododendron przewalskii in the headwater region of Minjiang River,China

本研究分析了岷江源区卡卡山典型高山灌丛植物陇蜀杜鹃不同发育阶段(花芽期和开花期)及不同海拔(3600 m低海拔和3800 m高海拔)下功能小枝和叶片性状的差异,以及空间异质性对花芽期和开花期小枝功能性状相关性及其权衡作用的影响。结果表明:低海拔同一生长期陇蜀杜鹃小枝长度显著大于高海拔,高海拔开花期小枝的花数量和花质量显著高于低海拔。同一海拔花芽期的小枝质量、叶片数量、总叶质量、总叶面积和总叶柄质量均显著大于开花期,单叶质量和单叶柄质量均显著小于开花期。与花芽期相比,开花期叶生物量占比减少了13%,而小枝质量占比显著增加。小枝的生物量权衡表明,花芽期性状倾向于小枝质量,开花期倾向于总叶质量;花芽期的叶偏好分配于单叶质量,低海拔和高海拔开花期叶片分别偏好分配到单叶柄质量和单叶质量。低海拔开花期小枝质量与总叶面积、总叶质量均为异速生长,单叶柄质量和单叶面积为异速生长。海拔和发育阶段共同影响了陇蜀杜鹃功能小枝和叶片的性状。

This study aimed at understanding the differences in traits of functional twigs and leaves of a typical alpine shrub species,Rhododendron przewalskii,at Kaka Mountain in the headwater region of Minjiang River.Leaf and twig traits were compared for shrubs at different growth stages(flower bud stage and flowering stage)and altitude(3600 m and 3800 m).The effects of spatial heterogeneity on their correlations and trade-offs were evaluated at leaf and twig levels,respectively.Our results showed that twig length was significantly longer at low altitude than high altitude for the shubs at the same growth stage.The number and mass of flowers at flowering stage were significantly higher at high altitude than those at low altitude.At the same altitude,twig mass,number of leaves,total leaf mass,total leaf area and total petiole mass were all significantly greater at the flower bud stage than those at the flowering stage,while the individual leaf mass and individual petiole mass at flower bud stage were significantly smaller than those at flowering stage.Compared with the flower bud stage,the proportion of leaf mass decreased by 13%at the flowering stage,while biomass proportion of twig significantly increased.At the flower bud stage,twig mass had a higher contribution to total twig mass.In contrast,the contribution of total leaf mass to total twig mass was higher at flowering stage.More biomass of leaf was allocated to individual leaf mass at flower bud stage.More biomass of leaf was allocated to individual petiole mass and individual leaf mass at flowering stage at low altitude and high altitude,respectively.At low altitude,allometric growth patterns presented between twig mass and total leaf area,total leaf mass.Similarly,individual petiole mass and individual leaf area had allometric growth.Our results indicated that the functional traits of twigs and leaves varied across both altitude and plant growth stage.