Direct evidence for phosphorus limitation on Amazon forest productivity.
Direct evidence for phosphorus limitation on Amazon forest productivity.
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磷限制对亚马逊森林生产力影响的直接证据。
DOI：
10.1038/s41586-022-05085-2
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发表时间：
2022
期刊：
影响因子：
64.8
通讯作者：
Cunha HFV
中科院分区：
文献类型：
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作者：
Cunha HFV
在高度风化的热带土壤上生长的雨林的生产力预计将受到磷可用性的限制。然而，控制施肥实验无法证明磷在控制热带森林净初级生产力方面的主导作用。最近的合成表明，对氮添加的反应与对磷的反应一样大，并且对低磷可用性的适应似乎能够在主要土壤磷梯度上保持净初级生产力。因此，磷的有效性在多大程度上限制了热带森林的生产力是高度不确定的。然而，亚马逊流域大部分地区的土壤磷含量比大多数热带施肥实验所进行的土壤更为贫乏。因此，我们在一个古老的亚马逊雨林中建立了磷、氮和碱基阳离子添加实验，该雨林的土壤磷含量较低，代表了亚马逊盆地约 60% 的土壤。在这里，我们表明净初级生产力仅随着磷的添加而增加。 2年后，细根（+29%）和冠层生产力（+19%）观察到强烈反应，但茎生长没有反应。磷对净初级生产力的限制的直接证据表明，磷的可用性可能会限制亚马逊森林对二氧化碳施肥的反应，这对未来的碳固存和森林对气候变化的适应能力产生重大影响。
The productivity of rainforests growing on highly weathered tropical soils is expected to be limited by phosphorus availability. Yet, controlled fertilization experiments have been unable to demonstrate a dominant role for phosphorus in controlling tropical forest net primary productivity. Recent syntheses have demonstrated that responses to nitrogen addition are as large as to phosphorus, and adaptations to low phosphorus availability appear to enable net primary productivity to be maintained across major soil phosphorus gradients. Thus, the extent to which phosphorus availability limits tropical forest productivity is highly uncertain. The majority of the Amazonia, however, is characterized by soils that are more depleted in phosphorus than those in which most tropical fertilization experiments have taken place. Thus, we established a phosphorus, nitrogen and base cation addition experiment in an old growth Amazon rainforest, with a low soil phosphorus content that is representative of approximately 60% of the Amazon basin. Here we show that net primary productivity increased exclusively with phosphorus addition. After 2 years, strong responses were observed in fine root (+29%) and canopy productivity (+19%), but not stem growth. The direct evidence of phosphorus limitation of net primary productivity suggests that phosphorus availability may restrict Amazon forest responses to CO2fertilization, with major implications for future carbon sequestration and forest resilience to climate change.