植物生态学报

• •    

胡杨当年生小枝茎构型对展叶效率的影响

李豪1,马如玉1,强 波1,贺 聪1,韩路2,王海珍2   

  1. 1. 塔里木大学
    2. 塔里木大学植物科学学院, 新疆生产建设兵团塔里木盆地生物资源保护利用重点实验室
  • 收稿日期:2020-12-23 修回日期:2021-08-17 出版日期:2021-09-02 发布日期:2021-09-02
  • 通讯作者: 王海珍
  • 基金资助:
    荒漠河岸林水盐梯度上植物功能性状格局与群落构建机制研究

Effect of current-year twig stem configuration on the leaf display efficiency of Populus euphratica

li hao1,ma ru yu1,qiang bo1,he cong2,Lu HANHai-Zhen WANG4   

  • Received:2020-12-23 Revised:2021-08-17 Online:2021-09-02 Published:2021-09-02
  • Contact: Hai-Zhen WANG

摘要: 植物功能性状反映植物适应环境变化过程中在不同器官形态与功能间的资源权衡与分配策略。枝叶是构建树冠的关键组分, 枝叶异速生长关系对理解荒漠植物生物量分配和生活史策略具有重要意义。该研究以胡杨(Populus euphratica)为研究对象, 以小枝茎长度、茎纤细率和茎体积表征茎构型, 以叶密度(单位茎长度的叶数量)、叶面积比(单位小枝茎干质量的总叶面积)和叶茎质量比(单位小枝茎干质量的总叶干质量)表征展叶效率, 采用标准化主轴回归(SMA)方法研究胡杨当年生小枝茎构型对展叶效率的影响及二者沿地下水埋深(GWD)梯度的权衡策略。结果显示, 胡杨当年生小枝茎直径、展叶效率和比叶面积、叶大小随GWD增加而降低, 小枝茎长度、茎纤细率及其上的叶数量则增大。小枝茎构型性状均与展叶效率呈显著负相关关系, 即随小枝茎长度、茎纤细率和茎体积的增加, 展叶效率逐渐降低, 可能是枝叶大小、水分传导与机械支撑间的权衡结果。小枝茎构型与展叶效率的异速生长指数(斜率)随GWD增加而增大, 因单位小枝茎投资获得的叶面积或者叶质量降低所致, 反映出随GWD增加胡杨采取了高消耗低收益的保守型策略。胡杨应对环境压力时, 倾向于在长枝上着生数量多的小叶, 短枝上着生数量少的大叶, 体现出胡杨小枝的资源利用策略与枝叶大小的权衡机制。综上所述, GWD显著影响胡杨小枝茎构型-展叶效率的权衡关系, 低展叶效率是胡杨应对日益旱化荒漠环境的适应策略。

关键词: 胡杨, 小枝茎构型, 展叶效率, 地下水埋深, 权衡关系

Abstract: Aims Plant functional traits indicated the resources trade-offs and allocation strategy between different organs and functions in the process of plant adapting to environmental changes. Branches and leaves were the key components of tree canopy, understanding the relationship of leaf-stem allometry was important for revealing adaptive strategies of desert plants with changing environmental constraints. In this study, our objective was to explore the scaling relationships between leaf display efficiency and current-year twig stem configuration, and trade-off strategy shift along groundwater gradients in extremely arid region. Methods Leaf number, area, mass and stem length, diameter, volume, mass of current-year twigs were measured for Populus euphratica with 30 trees within three different groundwater depths in Tarim basin, Xinjiang, China. The stem length, stem slender ratios and stem volume of current-year twigs were used as the proxy of stem configuration traits. Density of leaf number (leaf number per stem length), leaf area ratio (total leaf area per stem mass) and leaf/stem mass ratio (total leaf mass per stem mass) were used as the proxies of leaf display efficiency. The standardized major axis estimation (SMA) method was used to examine the scaling relationship between stem configuration traits and leaf display efficiency within current-year twigs across groundwater gradients. Important findings Stem diameter, leaf display efficiency, specific leaf area, individual leaf mass and area, all decreased with groundwater depths (GWD) increase, conversely, stem length, stem slender ratio and leaf number per twig increased, there were significant difference in stem and leaf functional traits across groundwater gradients. The density of leaf number, leaf area ratio and leaf/stem mass ratio as the proxies of leaf display efficiency, were all significantly negative correlated with stem length, stem slender ratio and stem volume within current-year twigs. This suggested that leaf display efficiency decreased with stem configuration variation within current-year twigs, which may reflect the trade-off of twig-leaf size, water conduction and mechanical support. The allometric exponents (slope) of stem configuration and leaf display efficiency decreased with GWD increase, as a result of the leaf area or mass per unit stem investment decreased with groundwater depths increase. It may reflect that the desert woody plants adopted a conservative adaptive strategy of high consumption and low benefit with habitat deterioration. When P. euphratica responded to environmental stress, it tended to have a large number of small leaves on long twigs, or tended to have relatively few large leaves on short twigs, which reflected the strategy of resources utilization and trade-off mechanism of twig-leaf size. Our results demonstrated that GWD was a key factor for regulating the leaf-stem allometric relationship, low leaf display efficiency was an adaptive strategy for P. euphratica to cope with the worsening arid desert environment.

Key words: Populus euphratica, stem configuration, leaf display efficiency, groundwater depth, trade-off