Above- and belowground linkages of a nitrogen and phosphorus co-limited tropical mountain pasture system – responses to nutrient enrichment
Above- and belowground linkages of a nitrogen and phosphorus co-limited tropical mountain pasture system – responses to nutrient enrichment
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DOI：
10.1007/s11104-015-2431-7
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发表时间：
2015-03
期刊：
影响因子：
4.9
通讯作者：
A. Tischer;Martin Werisch;Franziska Döbbelin;Tessa Camenzind;M. Rillig;Karin Potthast;U. Hamer
中科院分区：
文献类型：
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作者：
A. Tischer;Martin Werisch;Franziska Döbbelin;Tessa Camenzind;M. Rillig;Karin Potthast;U. Hamer
氮磷共限生态系统对单一养分富集的响应机制尚不清楚。本研究评估了氮磷共限牧草地上和地下生态系统组分对氮磷富集的敏感性及其相互关系。我们测试了植物的反应是否可以通过Ågren引入的串联营养素的概念来解释（Ecol Lett 7:185 - 191,2004）。在这个概念中，假设一种营养物质对生长速度的控制依赖于另一种营养物质对不同细胞过程的控制。方法研究了5年中量施氮、磷和N + P对sphacelata （Schumach.）草（setaria sphacelata）茎、根生物量和C:N:P化学计量的影响。此外，还研究了养分富集对土壤养分库、丛枝菌根真菌（AMF）以及微生物生物量、活性和群落结构（磷脂脂肪酸：PLFA）的影响。为了评估解释微生物反应的不同因素的重要性，我们应用了基于似然的信息论方法。结果施氮磷肥可使地上牧草生物量增加61%。磷处理（+ 45%）促进了根系生物量的增加。草的C:N:P化学计量通过改变P吸收（P处理）或通过将P从茎部转移到根（N处理）来响应。特别是在P和N处理下，根系C:N和C:P化学计量量下降。土壤C、N、P可提取组分受养分富集的影响显著。施磷增加了革兰氏阳性菌的生物量（+ 22%）和AMF的丰度（+ 46%），然而，信息技术方法的结果表明，营养物质的富集对微生物有间接影响。结论氮磷共限牧草对特定养分富集的响应支持了养分序列关联的概念。本研究证明了磷在植物对养分富集的响应中控制资源分配的根本重要性。牧草的资源配置而不是养分添加的直接影响驱动AMF、微生物生物量、群落结构和活性的变化。
AimLittle is known about how N and P co-limited ecosystems respond to single nutrient enrichment. This work assesses the susceptibility of above- and belowground ecosystem components and of their linkages in an N and P co-limited pasture to N- and P-enrichment. We tested if the plants’ responses can be explained by the concept of serially linked nutrients introduced by Ågren (Ecol Lett 7:185–191, 2004). In this concept, the control of the growth rate by one nutrient is assumed to depend on the control of a different cellular process by another nutrient.MethodsWe investigated the responses of shoot and root biomass and C:N:P stoichiometry of the grassSetaria sphacelata (Schumach.)to moderate N, P, and N + P application over 5 years. In addition, the effects of nutrient enrichment on soil nutrient pools, on arbuscular mycorrhizal fungi (AMF) as well as on microbial biomass, activity, and community structure (phospholipid fatty acids: PLFA) were tested. In order to evaluate the importance of different factors explaining microbial responses, we applied a likelihood-based information-theoretic approach.ResultsThe application of N + P increased aboveground grass biomass (+61 %). Root biomass was stimulated by P-treatment (+45 %). Grass C:N:P stoichiometry responded by altering the P-uptake (P-treatment) or by translocating P from shoot to root (N-treatment). In particular, root C:N and C:P stoichiometry decreased in P- and in N-treatment. Extractable fractions of soil C, N, and P were significantly affected by nutrient enrichment. P application increased the biomass of Gram-positive bacteria (+22 %) and the abundance of AMF (+46 %), however, results of the IT-approach suggested indirect effects of nutrient enrichment on microbes.ConclusionsThe responses of the N and P co-limited pasture to particular nutrient enrichment support the concept of serially linked nutrients. The present study provides evidence for the fundamental importance of P for controlling resource allocation of plants in responses to nutrient enrichment. Resource allocation of the grass rather than direct effects of nutrient additions drives changes in AMF, microbial biomass, community structure, and activity.