An ectomycorrhizal nitrogen economy facilitates monodominance in a neotropical forest
An ectomycorrhizal nitrogen economy facilitates monodominance in a neotropical forest
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DOI：
10.1111/ele.12570
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发表时间：
2016-04-01
期刊：
影响因子：
8.8
通讯作者：
Dalling, James W.
中科院分区：
文献类型：
--
作者：
Corrales, Adriana;Mangan, Scott A.;Dalling, James W.
热带森林以其高度多样性而闻名，但在许多地方，单一树种占林分中的大多数个体。对这些单一优势森林的解释仍然难以捉摸，但可能与菌根共生有关。我们测试了三个假设，通过这些假设，外生菌根可能会促进巴拿马山地热带森林中墨西哥奥雷穆尼树（Oreomunnea mexicana）的统治地位。我们测试了外生菌根网络是否可以改善幼苗的生长和存活，评估外生菌根真菌是否通过植物-土壤正反馈促进幼苗生长，并测量了 Oreomunnea 是否降低了无机氮的有效性。我们没有发现任何证据表明 Oreomunnea 受益于外生菌根网络或植物-土壤反馈。然而，我们发现外部土壤硝酸盐和铵浓度比 Oreomunnea 为主的森林内部高出三倍，并且地块中土壤硝酸盐和 Oreomunnea 丰度之间存在相关性。因此，外生菌根对氮循环的影响可能为全球外生菌根树种的单一优势提供了解释。
Tropical forests are renowned for their high diversity, yet in many sites a single tree species accounts for the majority of the individuals in a stand. An explanation for these monodominant forests remains elusive, but may be linked to mycorrhizal symbioses. We tested three hypotheses by which ectomycorrhizas might facilitate the dominance of the tree, Oreomunnea mexicana, in montane tropical forest in Panama. We tested whether access to ectomycorrhizal networks improved growth and survival of seedlings, evaluated whether ectomycorrhizal fungi promote seedling growth via positive plant-soil feedback, and measured whether Oreomunnea reduced inorganic nitrogen availability. We found no evidence that Oreomunnea benefits from ectomycorrhizal networks or plant-soil feedback. However, we found three-fold higher soil nitrate and ammonium concentrations outside than inside Oreomunnea-dominated forest and a correlation between soil nitrate and Oreomunnea abundance in plots. Ectomycorrhizal effects on nitrogen cycling might therefore provide an explanation for the monodominance of ectomycorrhizal tree species worldwide.