Colimitation and the coupling of N and P uptake kinetics in oligotrophic mountain streams

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• 作者：Leslie R. Piper ; Wyatt F. Cross ; Brian L. McGlynn
• 关键词：Colimitation ; Stream ecosystem ; Ecological stoichiometry ; Nitrogen and phosphorus uptake ; Tracer Additions for Spiraling Curve Characterization (TASCC)
• 刊名：Biogeochemistry
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：132
• 期：1-2
• 页码：165-184
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Biogeosciences; Ecosystems; Environmental Chemistry; Life Sciences, general;
• 出版者：Springer International Publishing
• ISSN：1573-515X
• 卷排序：132

文摘

Ecosystem element cycles can be tightly linked by both abiotic and biotic processes. Evidence for multi-element limitation (i.e., colimitation) of a variety of ecosystem processes is growing rapidly, yet our ability to quantify patterns of coupled nutrient dynamics at the ecosystem level has been hindered by logistical and methodological constraints. Here we quantify coupled nitrogen and phosphorus uptake kinetics in three oligotrophic mountain streams by using novel experimental techniques that quantify colimitation dynamics across a range of nutrient concentrations and stoichiometries. We show that relative demand for NO₃-N and PO₄-P varied across streams, but that short term availability of one nutrient consistently resulted in elevated, but variable, uptake of the other nutrient at all sites. We used temporally offset, pulsed nutrient additions to parameterize dual-nutrient Michaelis–Menten uptake surface models that represent NO₃-N and PO₄-P uptake at any given concentration or dissolved NO₃-N:PO₄-P stoichiometry. Our results indicated that the uptake of N and P were strongly enhanced in the presence of the other nutrient. Surface models quantitatively reflect patterns of colimitation and multi-element demand in streams, and should allow for parameterization of more realistic stream network models that explicitly account for interactions among element cycles.