Modeling the carbon cost of plant nitrogen acquisition: Mycorrhizal trade-offs and multipath resistance uptake improve predictions of retranslocation
Modeling the carbon cost of plant nitrogen acquisition: Mycorrhizal trade-offs and multipath resistance uptake improve predictions of retranslocation
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DOI：
10.1002/2014jg002660
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发表时间：
2014-08-01
影响因子：
3.7
通讯作者：
Phillips, Richard P.
中科院分区：
文献类型：
--
作者：
Brzostek, Edward R.;Fisher, Joshua B.;Phillips, Richard P.
陆地生物圈模型对未来陆地碳（C）汇的准确预测取决于对净初级生产力的营养约束如何表现。虽然养分限制几乎是普遍的，目前的模式没有一个C成本的植物养分收购。同样缺少的是共生菌根真菌，它们可以消耗高达20%的净初级生产，并提供高达50%的植物氮（N）吸收。在这里，我们整合同步吸收和真菌进入一个先进的植物氮模型固定和吸收氮（FUN），可以耦合到陆地生物圈模型。C成本的N收购作为菌根类型的函数而变化，与植物，支持丛枝菌根受益时，N相对丰富，植物，支持外生菌根受益时，N是强烈限制。在6个温带森林的网站（代表丛枝菌根和外生菌根占主导地位的立场和176网站年），包括多路径阻力提高了地上和地下来源之间的氮吸收的分区。与原始模型相比，整合真菌素导致从土壤（R-2=0.69增加到R-2=0.96）和衰老叶片（R-2=0.29增加到R-2=0.73）中吸收N的预测进一步改善。平均而言，5%和9%的净初级生产力的丛枝菌根和外生菌根为主的森林，分别需要支持菌根介导的收购N。在某种程度上，资源限制净初级生产力是由类似的权衡在所有陆地生态系统，将这些改进FUN到陆地生物圈模型应加强对未来的土地碳汇的预测。
Accurate projections of the future land carbon (C) sink by terrestrial biosphere models depend on how nutrient constraints on net primary production are represented. While nutrient limitation is nearly universal, current models do not have a C cost for plant nutrient acquisition. Also missing are symbiotic mycorrhizal fungi, which can consume up to 20% of net primary production and supply up to 50% of a plant's nitrogen (N) uptake. Here we integrate simultaneous uptake and mycorrhizae into a cutting-edge plant N modelFixation and Uptake of Nitrogen (FUN)that can be coupled into terrestrial biosphere models. The C cost of N acquisition varies as a function of mycorrhizal type, with plants that support arbuscular mycorrhizae benefiting when N is relatively abundant and plants that support ectomycorrhizae benefiting when N is strongly limiting. Across six temperate forested sites (representing arbuscular mycorrhizal- and ectomycorrhizal-dominated stands and 176 site years), including multipath resistance improved the partitioning of N uptake between aboveground and belowground sources. Integrating mycorrhizae led to further improvements in predictions of N uptake from soil (R-2=0.69 increased to R-2=0.96) and from senescing leaves (R-2=0.29 increased to R-2=0.73) relative to the original model. On average, 5% and 9% of net primary production in arbuscular mycorrhizal- and ectomycorrhizal-dominated forests, respectively, was needed to support mycorrhizal-mediated acquisition of N. To the extent that resource constraints to net primary production are governed by similar trade-offs across all terrestrial ecosystems, integrating these improvements to FUN into terrestrial biosphere models should enhance predictions of the future land C sink.