reference : Trends in stream nitrogen concentrations for forested reference catchments across the USA

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Bibliographic fields
reftype Journal Article
Abstract To examine whether stream nitrogen concentrations in forested reference catchments have changed over time and if patterns were consistent across the USA, we synthesized up to 44 yr of data collected from 22 catchments at seven USDA Forest Service Experimental Forests. Trends in stream nitrogen presented high spatial variability both among catchments at a site and among sites across the USA. We found both increasing and decreasing trends in monthly flow-weighted stream nitrate and ammonium concentrations. At a subset of the catchments, we found that the length and period of analysis influenced whether trends were positive, negative or non-significant. Trends also differed among neighboring catchments within several Experimental Forests, suggesting the importance of catchment-specific factors in determining nutrient exports. Over the longest time periods, trends were more consistent among catchments within sites, although there are fewer long-term records for analysis. These findings highlight the critical value of long-term, uninterrupted stream chemistry monitoring at a network of sites across the USA to elucidate patterns of change in nutrient concentrations at minimally disturbed forested sites.
Author Argerich, A.; S. L. Johnson; S. D. Sebestyen; C. C. Rhoades; E. Greathouse; J. D. Knoepp; M. B. Adams; G. E. Likens; J. L. Campbell; W. H. McDowell; F. N. Scatena; G. G. Ice
DOI 10.1088/1748-9326/8/1/014039
ISSN 1748-9326
Issue 1
Journal Environmental Research Letters
Pages 014039
Title Trends in stream nitrogen concentrations for forested reference catchments across the USA
Volume 8
Year 2013
Bibliographic identifiers
_record_number 22013
_uuid 8c6e713b-c943-4d9f-a3a9-2333218d6587