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    树种混交对油松人工林化学计量特征及养分再吸收效率的影响

    Effects of tree species mixing on stoichiometric characteristics and nutrient resorption efficiency of Pinus tabuliformis plantations

    • 摘要:
      目的 探讨不同树种混交对北京山区油松人工林叶片、凋落物和土壤化学计量特征、养分再吸收效率及内稳态的影响,为油松人工林可持续经营提供科学依据。
      方法 以油松纯林为对照,选取油松−糠椴混交林、油松−蒙古栎混交林以及油松−山桃和山杏混交林作为研究对象,系统测定叶片、凋落物和土壤中C、N、P的含量及化学计量比,并基于异速生长关系和养分再吸收效率,深入分析植物养分内稳态机制及养分利用策略。
      结果 油松−蒙古栎混交林表现出最优的养分状况,其叶片N含量、N∶P以及土壤C、N含量和C∶P、N∶P均显著高于其他林分。油松−糠椴混交林叶片C∶N和C∶P最高,表现出保守型养分利用策略。混交林凋落物的C、N含量及N∶P均高于纯林,表明具有更快的养分循环速率。在再吸收效率方面,油松−蒙古栎混交林对N的再吸收效率最高,油松−糠椴混交林对P的再吸收效率最高,且均高于纯林。4种林分叶片P含量均不受土壤P含量变化的影响,表现出较高的内稳态。
      结论 与纯林相比,树种混交尤其是油松−蒙古栎混交能显著改善林分的养分状况,提高土壤肥力和养分再吸收效率,是北京山区油松低效人工林改造的适宜模式。在森林经营实践中,建议优先选择生态位互补的树种进行混交配置,以增强系统养分循环效率并提升生态稳定性。

       

      Abstract:
      Objective This study aimed to explore the effects of tree species mixing on stoichiometric characteristics, nutrient resorption efficiency, and homeostasis of leaves, litter, and soil in Pinus tabuliformis plantations in mountainous areas of Beijing, northern China to provide a scientific basis for sustainable management of P. tabuliformis plantations.
      Method Pure P. tabuliformis plantation, P. tabuliformis + Tilia mandshurica mixed plantation (PT), P. tabuliformis + Quercus mongolica mixed plantation (PQ), and P. tabuliformis + Prunus davidiana + Prunus sibirica mixed plantation (PR) were measured for C, N, and P contents and stoichiometry in leaves, litter and soil. Nutrient resorption efficiency and homeostasis were assessed using allometric growth and resorption efficiency models.
      Result The PQ plantation showed optimal nutrient status, with significantly higher leaf N content and N∶P, as well as elevated soil C, N, C∶P and N∶P. The PT plantation had the highest leaf C∶N and C∶P, indicating a conservative nutrient strategy. Tree species mixing generally had higher litter C, N and N∶P than pure stands, suggesting enhanced decomposition and nutrient release potential. PQ and PT exhibited the highest N and P resorption efficiency, respectively, both exceeding pure P. tabuliformis stand. All four stands maintained strong P homeostasis, with leaf P content unaffected by soil P variation.
      Conclusion Compared with pure stand, tree species mixing, particularly the PQ plantations significantly enhance nutrient status, soil fertility and resorption efficiency, providing an optimal model for transforming low-efficiency plantations in Beijing mountainous areas. Prioritizing ecologically complementary species in mixing is recommended to improve nutrient cycling and ecosystem stability.

       

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