Scaling plant nitrogen use and uptake efficiencies in response to nutrient addition in peatlands
Scaling plant nitrogen use and uptake efficiencies in response to nutrient addition in peatlands
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DOI：
10.1890/09-0064.1
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发表时间：
2010-03-01
期刊：
影响因子：
4.8
通讯作者：
Kellogg, Laurie E.
中科院分区：
文献类型：
--
作者：
Iversen, Colleen M.;Bridgham, Scott D.;Kellogg, Laurie E.
氮(N)是许多陆地生态系统中主要的生长限制养分，因此植物单位氮吸收产量（即氮利用效率，NUE）是生态系统功能的一个重要组成部分。氮素利用效率包括两个组成部分：氮生产力（A(N)，每峰值生物量氮含量的植物产量）和氮在植物生物量中的平均停留时间（MRTN）。本研究利用一项为期5年的施肥试验，在多个生物尺度（即从叶片到群落水平）上研究氮和磷(P)有效性的增加对植物氮肥利用效率的影响方式。我们在密歇根上半岛的一个营养有限的泥炭地生态系统的自然梯度施肥。美国，6克N.m（-2）。年（-1），2 g p.m.(-2)-年（-1），或N和p的组合。我们的目标是确定植物体内碳和氮分配给叶片和木本组织的变化以及群落内物种组成的变化，包括地上和地下，将如何影响(1)氮肥利用；(2) NUE各分量间的自适应权衡；(3)植物从土壤中吸收氮的效率（氮吸收效率）。(4)植物群落单位土壤氮有效性产量（N响应效率，NRE）。正如预期的那样，氮和磷的添加普遍增加了地上部产量和氮的吸收。特别是磷有效性对植物吸收和利用氮的方式有强烈影响。氮素利用效率对养分添加的响应并不简单。氮利用效率在叶片和木质组织之间、物种之间以及在营养型-微营养型梯度之间存在差异，这是因为植物和群落适应于最大化A(N)或MRTN，而不是同时最大化两者。氮有效度的增加严重降低了植物和群落的氮吸收效率，而磷有效度的增加则提高了氮吸收效率，特别是在固氮灌木中。氮素吸收效率比氮素利用效率更能控制植物群落对土壤氮素有效性的响应，地上和地下群落氮素吸收效率对养分添加的响应类似。我们的研究结果表明，植物在多个生物尺度上响应养分有效性，我们认为氮吸收效率可能比植物氮肥利用效率更能代表植物对养分有效性梯度的响应。
Nitrogen (N) is the primary growth-limiting nutrient in many terrestrial ecosystems, and therefore plant production per unit N taken up (i.e., N use efficiency, NUE) is a fundamentally important component of ecosystem function. Nitrogen use efficiency comprises two components: N productivity (A(N), plant production per peak biomass N content) and the mean residence time of N in plant biomass (MRTN). We utilized a five-year fertilization experiment to examine the manner in which increases in N and phosphorus (P) availability affected plant NUE at multiple biological scales (i.e., from leaf to community level). We fertilized a natural gradient of nutrient-limited peatland ecosystems in the Upper Peninsula of Michigan. USA, with 6 g N.m(-2).yr(-1), 2 g P.m(-2)-yr(-1), or a combination of N and P. Our objectives were to determine how changes in carbon and N allocation within a plant to leaf and woody tissue and changes in species composition within a community, both above- and belowground, would affect (1) NUE; (2) the adaptive trade-off between the components of NUE; (3) the efficiency with which plants acquired N from the soil (N uptake efficiency). and (4) plant community production per unit soil N availability (N response efficiency, NRE). As expected, N and P addition generally increased aboveground production and N uptake. In particular, P availability strongly affected the way in which plants took up and used N. Nitrogen use efficiency response to nutrient addition was not straightforward. Nitrogen use efficiency differed between leaf and woody tissue, among species, and across the ombrotrophic-minerotrophic gradient because plants and communities were adapted to maximize either A(N) or MRTN, but not both concurrently. Increased N availability strongly decreased plant and community N uptake efficiency, while increased P availability increased N uptake efficiency, particularly in a nitrogen-fixing shrub. Nitrogen uptake efficiency was more important in controlling overall plant community response to soil N availability than was NUE, and above- and belowground community N uptake efficiencies responded to nutrient addition in a similar manner. Our results demonstrate that plants respond to nutrient availability at multiple biological scales, and we suggest that N uptake efficiency may be a more representative measurement of plant responses to nutrient availability gradients than plant NUE.