Successional dynamics of nitrogen fixation and forest growth in regenerating Costa Rican rainforests.
Successional dynamics of nitrogen fixation and forest growth in regenerating Costa Rican rainforests.
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DOI：
10.1002/ecy.2637
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发表时间：
2019-03
期刊：
影响因子：
4.8
通讯作者：
B. Taylor;R. Chazdon;D. Menge
中科院分区：
文献类型：
--
作者：
B. Taylor;R. Chazdon;D. Menge
再生的热带森林具有巨大的碳捕获能力和保护生物多样性。干扰后氮循环的恢复可以促进生物量的再生，但很少有研究对热带森林氮和氮输入的演替动态进行评估。我们评估了共生和非共生固氮作用、土壤无机氮浓度和树木生长情况，研究了从19年树龄到原生林的5个热带森林样地。湿季土壤无机氮浓度在各样地均较高，在29年样地最高。共生固氮投入随着演替而减少，而非共生固氮投入在37岁样地达到峰值。因此，主要的固氮输入从年轻样地的共生固氮转变为年老样地的非共生固氮。树木生长在最年轻的样地最高，随演替而下降。有趣的是，在我们的研究中，共生固氮与固氮树的基底面积呈负相关，这突出了用固氮树来代替共生固氮率的危险。我们的研究结果表明，氮循环在干扰后的19年里得到了很大程度的恢复，这使得我们的场地能够快速地进行生物量再生。这项工作为了解支持新热带森林生长和碳捕获的氮的来源和动态提供了重要的见解。
Regenerating tropical forests have an immense capacity to capture carbon and harbor biodiversity. The recuperation of the nitrogen cycle following disturbance can fuel biomass regeneration, but few studies have evaluated the successional dynamics of nitrogen and nitrogen inputs in tropical forests. We assessed symbiotic and asymbiotic nitrogen fixation, soil inorganic nitrogen concentrations, and tree growth in a well-studied series of five tropical forest plots ranging from 19 yr in age to old-growth forests. Wet-season soil inorganic nitrogen concentrations were high in all plots, peaking in the 29-yr-old plot. Inputs from symbiotic nitrogen fixation declined through succession, while asymbiotic nitrogen fixation peaked in the 37-yr-old plot. Consequently, the dominant nitrogen fixation input switched from symbiotic fixation in the younger plots to asymbiotic fixation in the older plots. Tree growth was highest in the youngest plots and declined through succession. Interestingly, symbiotic nitrogen fixation was negatively correlated with the basal area of nitrogen-fixing trees across our study plots, highlighting the danger in using nitrogen-fixing trees as a proxy for rates of symbiotic nitrogen fixation. Our results demonstrate that the nitrogen cycle has largely recuperated by 19 yr following disturbance, allowing for rapid biomass regeneration at our site. This work provides important insight into the sources and dynamics of nitrogen that support growth and carbon capture in regenerating Neotropical forests.