Mirror Lake, New Hampshire 170 Year Tree Ring Nitrogen Isotope Data McLauchlan, K.K.; Craine, J.M.; Oswald, W.; Leavitt, P.R.; Likens, G.E. McLauchlan, K.K. Craine, J.M. Oswald, W. Leavitt, P.R. Likens, G.E. biogeochemical cycles ACSH Acer saccharum Marsh. sugar maple earth science/paleoclimate/tree ring (delta 15N,wood,null,per mil,null,tree ring,normalized,isotope ratio mass spectrometry,N,"Betula papyrifera, standardized to a mean of zero") earth science/paleoclimate/tree ring (delta 15N,wood,null,per mil,null,tree ring,normalized,isotope ratio mass spectrometry,N,"Fagus grandifolia, standardized to a mean of zero") earth science/paleoclimate/tree ring (delta 15N,wood,null,per mil,null,tree ring,normalized,isotope ratio mass spectrometry,N,"Tsuga canadensis, standardized to a mean of zero") earth science/paleoclimate/tree ring (delta 15N,wood,null,per mil,null,tree ring,normalized,isotope ratio mass spectrometry,N,"Acer saccharum, standardized to a mean of zero") earth science/paleoclimate/tree ring (age,null,null,year Common Era,null,tree ring,null,null,N,null) earth science/paleoclimate/tree ring (delta 15N,wood,null,per mil,null,tree ring,normalized,isotope ratio mass spectrometry,N,"Fraxinus americana, standardized to a mean of zero") earth science/paleoclimate/tree-ring (Mirror Lake>LATITUDE 43.6167>LONGITUDE -71.25) Nitrogen (N) availability, defined here as the supply of N to terrestrial plants and soil microorganisms relative to their N demands, limits the productivity of many temperate zone forests and in part determines ecosystem carbon (C) content. Despite multidecadal monitoring of N in streams, the long-term record of N availability in forests of the northeastern United States is largely unknown. Therefore, although these forests have been receiving anthropogenic N deposition for the past few decades, it is still uncertain whether terrestrial N availability has changed during this time and, subsequently, whether forest ecosystems have responded to increased N deposition. Here, we used stable N isotopes in tree rings and lake sediments to demonstrate that N availability in a northeastern forest has declined over the past 75 years, likely because of ecosystem recovery from Euro-American land use. Forest N availability has only recently returned to levels forecast from presettlement trajectories, rendering the trajectory of future forest N cycling uncertain. Our results suggest that chronic disturbances caused by humans, especially logging and agriculture, are major drivers of terrestrial N cycling in forest ecosystems today, even a century after cessation. STUDY NOTES: Nitrogen isotopic data (d15N) for 5 tree species for the past 150 years, from cores collected near Mirror Lake, New Hampshire. Data from cores of Tsuga canadensis, Acer saccharum, Betula papyrifera, Fagus grandifolia, and Fraxinus americana are included. 5.15-mm diameter increment bores were acquired from 22 trees divided among the three subwatersheds of Mirror Lake. Each bore was cut into 30-mg sections with sections divided along boundaries between ring widths. On average, a section contained wood deposited during 2.75 years. The 15N:14N ratio of each section was determined at the University of California, Davis, on a PDZ Europa 20-20 isotope ratio mass spectrometer. IITRDB008 NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : McLauchlan, K.K. Investigator : Craine, J.M. Investigator : Oswald, W. Investigator : Leavitt, P.R. Investigator : Likens, G.E. 2013-10-28 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/15311 https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/northamerica/usa/newhampshire/mirror2007tsca-d15n.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/northamerica/usa/newhampshire/mirror2007acsa-d15n.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/northamerica/usa/newhampshire/mirror2007bepa-d15n.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/northamerica/usa/newhampshire/mirror2007fagr-d15n.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/northamerica/usa/newhampshire/mirror2007fram-d15n.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/northamerica/usa/newhampshire/mirror2007tsca-d15n.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/northamerica/usa/newhampshire/mirror2007acsa-d15n.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/northamerica/usa/newhampshire/mirror2007bepa-d15n.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/northamerica/usa/newhampshire/mirror2007fagr-d15n.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/northamerica/usa/newhampshire/mirror2007fram-d15n.txt English https://www.ncdc.noaa.gov/paleo/study/15311 https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/northamerica/usa/newhampshire/mirror2007tsca-d15n.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/northamerica/usa/newhampshire/mirror2007acsa-d15n.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/northamerica/usa/newhampshire/mirror2007bepa-d15n.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/northamerica/usa/newhampshire/mirror2007fagr-d15n.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/northamerica/usa/newhampshire/mirror2007fram-d15n.txt Kendra K. McLauchlan, Joseph M. Craine, W. Wyatt Oswald, Peter R. Leavitt, and Gene E. Likens2007Changes in nitrogen cycling during the past century in a northern hardwood forestProceedings of the National Academy of Sciences104187466-747010.1073/pnas.0610546104 START YEAR: 1835 AD * END YEAR: 2005 AD -71.25 43.6167 -71.25 43.6167