Nutrient availability in the bog.
We deployed ion-exchange resins across hummock-hollow microtopography in two locations in each SPRUCE experimental plot. Resins are retrieved every 28 days during the growing season to assess plant-available NH4-N, NO3-N, and PO4 throughout the peat profile, and to track changes in plant-available nutrients in response to warming and elevated [CO2].

Thus far, warming—combined with a longer frost-free period—has increased the amount of NH4-N and PO4-P adsorbed to ion-exchange resins in the warmest treatment enclosures. However, the increase in nutrients was initially much greater below the rooting zone, potentially indicating plant uptake in surface peat (i.e., greater competition for nutrients). In recent years, we have observed large spikes in resin-available nutrients in the shallow peat of the warmest enclosures, likely due to the death and decay of Sphagnum mosses.
Publications.
Iversen CM, Latimer J, Brice DJ, Childs J, Vander Stel HM, Graham J, Griffiths N, Malhotra A, Norby RJ, Olehieser K, Phillips J, Salmon VG, Sebestyen SD, Yang X, Hanson PJ. 2022. Whole-ecosystem warming increases plant-available nitrogen and phosphorus in the SPRUCE bog. Ecosystems, on-line.

Iversen CM, Childs J, Norby RJ, Ontl TA, Kolka RK, Brice DJ, McFarlane KJ, Hanson PJ. 2018. Fine-root growth in a forested bog is seasonally dynamic, but shallowly distributed in nutrient-poor peat. Plant and Soil 424: 123-143.
Related Publications.
Carrell AA, Kolton M, Glass JB, Pelletier DA, Warren MJ, Kostka JE, Iversen CM, Hanson PJ, Weston DJ. 2019. Experimental warming alters the community composition, diversity, and N2 fixation activity of peat moss (Sphagnum fallax) microbiomes. Global Change Biology 25: 2993-3004.

Salmon VG, Brice DJ, Bridgham S, Childs J, Graham J, Griffiths NA, Hofmockel K, Iversen CM, Jicha TM, Kolka RK, Kostka JE, Malhotra A, Norby RJ, Phillips JR, Ricciuto D, Schadt CW, Sebestyen SD, Shi X, Walker AP, Warren JM, Weston DJ, Yang X, Hanson PJ. 2021. Nitrogen and phosphorus cycling in an ombrotrophic peatland: a benchmark for assessing change. Plant and Soil 466: 649 -674.

Shelley SJ, Brice DJ, Iversen CM, Kolka RK, Sebestyen SD, Griffiths NA. 2022. Deciphering the shifting role of intrinsic and extrinsic drivers on moss decomposition in peatlands over a 5-year period. Oikos, https://doi.org/10.1111/oik.08584.
Data Sets.
Iversen CM, Ontl TA, Brice DJ, Childs J. 2017. SPRUCE S1 Bog plant-available nutrients assessed with ion-exchange resins from 2011-2012 in the Southern end of the S1 bog. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A. Data set accessed at http://dx.doi.org/10.3334/CDIAC/spruce.022.

Iversen CM, Latimer J, Burnham A, Brice DJ, Childs J, Vander Stel HM. 2017. SPRUCE plant-available nutrients assessed with ion-exchange resins in experimental plots, beginning in 2013. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.

Related projects.

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