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    干热河谷优势灌木养分重吸收率及其C∶N∶P化学计量特征

    Nutrient reabsorption efficiency of dominant shrubs in dry-hot valley and its C∶N∶P stoichiometry

      摘要
    • 摘要:
      目的探讨干热河谷区灌木植物成熟叶与衰老叶之间的养分重吸收率及其C∶N∶P化学计量特征。
      方法以坡柳、马桑和苦刺为研究对象，运用单因素方差分析和Pearson相关性分析，测定并计算其鲜叶、凋落叶的养分含量、重吸收率及其C∶N∶P化学计量比。
      结果除凋落叶N含量表现为马桑 > 苦刺 > 坡柳外，鲜叶N、P及凋落叶P含量均表现为苦刺 > 坡柳 > 马桑。苦刺N重吸收率最高，坡柳P重吸收率最高。3种灌木鲜叶和凋落叶C∶N、C∶P均存在显著差异性（P < 0.05），N∶P无显著差异。此外坡柳N重吸收率与凋落叶C∶N、P重吸收率与鲜叶C:N具有显著相关性（P < 0.05），马桑N重吸收率与鲜叶C∶N、凋落叶N:P和P重吸收率与鲜叶C∶N、N∶P均呈显著负相关（P < 0.05），苦刺N重吸收率与凋落叶C∶N、N∶P具有显著相关性（P < 0.05）。3种灌木除鲜叶N含量与土壤中水解氮（AN）含量存在显著相关性外，鲜叶和凋落叶C、N、P含量与土壤中各养分含量均无显著相关性。
      结论3种灌木除在生长过程中受 P限制外，N、P含量均表现为不完全吸收，N、P重吸收率均低于全球尺度上多种陆生植物的养分重吸收率，说明干热河谷坡柳、马桑和苦刺成熟植株通过养分重吸收来适应贫瘠立地的能力弱化，N、P养分保存和自身转移能力较低。

       

      Abstract:
      ObjectiveThis paper aims to explore the leaf nutrient content before and after senescing, nutrient reabsorption efficiency(RE) and C∶N∶P stoichiometry of Dodonaea viscose, Coriaria sinica and Sophora davidii in hot and dry valley.
      MethodOne way analysis of variance and Pearson correlation analysis were used.
      ResultThe results showed that the contents of nitrogen (N) in litter were as follows: C. sinica > S. davidii > D. viscose, the contents of nitrogen (N) and phosphorus (P) in fresh leaves, P in litter followed an order of S. davidii > D. viscose > C. sinica. S. davidii’s N had the highest reabsorption efficiency. And the reabsorption efficiency of D. viscose’s P was the highest. There were significant differences (P < 0.05) between the three shrub fresh leaves and litter C∶N, C∶P, however, N∶P had no significant difference. In addition, N reabsorption efficiency of D. viscose was significantly correlated (P < 0.05) with C∶N of the litter, and P reabsorption efficiency was significantly correlated with C∶N of the fresh leaf. At the same time, N reabsorption efficiency of C. sinica was significantly and negatively correlated with C∶N of the fresh leaf, N∶P of the litter, P reabsorption efficiency was significantly and negatively correlated with C∶N, N∶P of the fresh leaf, and N reabsorption efficiency of S. davidii was significantly correlated with C∶N, N∶P of the litter. Except for the significant correlation between the N content of fresh leaves and the AN content in soil, there was no significant correlation between the contents of C, N and P in the leaves and the contents of nutrients in the soil.
      ConclusionOn the whole, the three shrubs are restricted by P during the growth process, and the N and P contents are all incompletely absorbed. In addition, the N and P reabsorption rates are lower than the nutrient reabsorption rates of various terrestrial plants on a global scale. It shows that the ability of the dry heat valley D. viscose, C. sinica and S. davidii shrubs to adapt to the barren land through nutrient reabsorption is gradually weakened, and the N and P nutrient preservation ability is reduced.

       

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