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dc.contributor.authorQubain, C.A.
dc.contributor.authorYano, Y.
dc.contributor.authorHu, J.
dc.date.accessioned2021-06-05T02:34:53Z
dc.date.available2021-06-05T02:34:53Z
dc.date.issued2021
dc.identifier.citationQubain, C. A., Yano, Y., & Hu, J. (2021). Nitrogen acquisition strategies of mature Douglas‐fir: a case study in the northern Rocky Mountains. Ecosphere, 12(1), e03338.
dc.identifier.issn2150-8925
dc.identifier.doi10.1002/ecs2.3338
dc.identifier.urihttp://hdl.handle.net/10150/659740
dc.description.abstractNitrogen (N) limits plant growth in temperate ecosystems, yet many evergreens exhibit low photosynthetic N use efficiency, which can be explained in part by their tendency to store more N than to use it in photosynthesis. However, it remains uncertain to what extent mature conifers translocate internal N reserves or take up N from soils to support new growth. In this study, we explored N dynamics within mature Douglas-fir (Pseudotsuga menziesii var. glauca) trees by linking N uptake in field-grown trees with seasonal soil available N. We used a branch-level mass balance approach to infer seasonal changes in total N among multiple needle and stem cohorts and bole tissue, and used foliar δ15N to evaluate N translocation/uptake from soils. Soil resin-exchangeable N and net N transformation rates were measured to assess whether soils had sufficient N to support new needle growth. We estimated that after bud break, new needle biomass in Douglas-fir trees accumulated an average of 0.20 ± 0.03 mg N/branch and 0.17 ± 0.03 mg N/branch in 2016 and 2017, respectively. While we did find some evidence of translocation of N from older stems to buds prior to bud break, we did not detect a significant drawdown of N from previous years’ growth during needle expansion. This suggests that the majority of N used for new growth was not reallocated from aboveground storage, but originated from the soils. This finding was further supported by the δ15N data, which showed divergent δ15N patterns between older needles and buds prior to leaf flushing (indicative of translocation), but similar patterns of depletion and subsequent enrichment following leaf expansion (indicative of N originating from soils). Overall, in order to support new growth, our study trees obtained the majority of N from the soils, suggesting tight coupling between soil available N and N uptake in the ecosystem. © 2021 The Authors.
dc.language.isoen
dc.publisherWiley-Blackwell
dc.rightsCopyright © 2021 The Authors. This is an open access article under the terms of the Creative Commons Attribution License.
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.subjectconifer
dc.subjectevergreen
dc.subjectnitrogen availability
dc.subjectnitrogen storage
dc.subjectnitrogen translocation
dc.subjectnitrogen uptake
dc.subjectPseudotsuga menziesii var. glauca/Rocky Mountain Douglas-fir
dc.titleNitrogen acquisition strategies of mature Douglas-fir: a case study in the northern Rocky Mountains
dc.typeArticle
dc.typetext
dc.contributor.departmentSchool of Natural Resources and the Environment, University of Arizona
dc.identifier.journalEcosphere
dc.description.noteOpen access journal
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.
dc.eprint.versionFinal published version
dc.source.journaltitleEcosphere
refterms.dateFOA2021-06-05T02:34:53Z


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Copyright © 2021 The Authors. This is an open access article under the terms of the Creative Commons Attribution License.
Except where otherwise noted, this item's license is described as Copyright © 2021 The Authors. This is an open access article under the terms of the Creative Commons Attribution License.