Patterns and controls of foliar nutrient stoichiometry and flexibility across United States forests
Patterns and controls of foliar nutrient stoichiometry and flexibility across United States forests
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美国森林叶片营养化学计量学和灵活性的模式和控制
DOI：
10.1002/ecy.3909
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发表时间：
2023-01-05
期刊：
影响因子：
4.8
通讯作者：
Cleveland, Cory C.
中科院分区：
文献类型：
--
作者：
Dynarski, Katherine A.;Soper, Fiona M.;Cleveland, Cory C.
植物元素化学计量和化学计量灵活性强烈调节生态系统对全球变化的反应。在这里，我们使用来自美国陆地森林国家生态观测网络站点的成对叶片和土壤养分数据，测试了三个潜在的机械驱动因素(气候、土壤养分和植物分类学)。我们发现，叶面氮(N)和叶面磷(P)的广泛模式可以用不同的机制来解释。植物分类学是控制所有叶片营养化学计量和浓度的重要因素，尤其是叶N，它主要与分类学有关，不随气候或土壤梯度而变化。尽管N与环境变量之间缺乏立地水平的相关性，但叶片N表现出种内灵活性，叶片N与各种环境因子之间存在大量物种特有的相关性，表明叶片化学和化学计量弹性可以在不同的时空尺度上表现出来。除植物分类外，叶面磷和氮磷比还与土壤养分状况(可提取磷)和气候，特别是实际蒸散速率有关。我们的发现突出了影响叶片化学的无数因素，并表明广泛的模式不能用单一的一致机制来解释。此外，对叶面N和P的不同控制表明，它们可能在不同的空间和时间尺度上对全球变化驱动因素敏感，可能导致生态系统N：P比率的改变，从而对从生产力到碳固存的各种过程产生影响。
Plant element stoichiometry and stoichiometric flexibility strongly regulate ecosystem responses to global change. Here, we tested three potential mechanistic drivers (climate, soil nutrients, and plant taxonomy) of both using paired foliar and soil nutrient data from terrestrial forested National Ecological Observatory Network sites across the USA. We found that broad patterns of foliar nitrogen (N) and foliar phosphorus (P) are explained by different mechanisms. Plant taxonomy was an important control over all foliar nutrient stoichiometries and concentrations, especially foliar N, which was dominantly related to taxonomy and did not vary across climate or soil gradients. Despite a lack of site-level correlations between N and environment variables, foliar N exhibited intraspecific flexibility, with numerous species-specific correlations between foliar N and various environmental factors, demonstrating the variable spatial and temporal scales on which foliar chemistry and stoichiometric flexibility can manifest. In addition to plant taxonomy, foliar P and N:P ratios were also linked to soil nutrient status (extractable P) and climate, especially actual evapotranspiration rates. Our findings highlight the myriad factors that influence foliar chemistry and show that broad patterns cannot be explained by a single consistent mechanism. Furthermore, differing controls over foliar N versus P suggests that each may be sensitive to global change drivers on distinct spatial and temporal scales, potentially resulting in altered ecosystem N:P ratios that have implications for processes ranging from productivity to carbon sequestration.