Total C and N Pools and Fluxes Vary with Time, Soil Temperature, and Moisture Along an Elevation, Precipitation, and Vegetation Gradient in Southern Appalachian Forests
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The interactions of terrestrial C pools and fluxes with spatial and temporal variation in climate are not well understood. We conducted this study in the southern Appalachian Mountains where complex topography provides variability in temperature, precipitation, and forest communities. In 1990, we established five large plots across an elevation gradient allowing us to study the regulation of C and N pools and cycling by temperature and water, in reference watersheds in Coweeta Hydrologic Laboratory, a USDA Forest Service Experimental Forest, in western NC, USA. Communities included mixed-oak pine, mixed-oak, cove hardwood, and northern hardwood. We examined 20-year changes in overstory productivity and biomass, leaf litterfall C and N fluxes, and total C and N pools in organic and surface mineral soil horizons, and coarse wood, and relationships with growing season soil temperature and precipitation. Productivity increased over time and with precipitation. Litterfall C and N flux increased over time and with increasing temperature and precipitation, respectively. Organic horizon C and N did not change over time and were not correlated to litterfall inputs. Mineral soil C and N did not change over time, and the negative effect of temperature on soil pools was evident across the gradient. Our data show that increasing temperature and variability in precipitation will result in altered aboveground productivity. Variation in surface soil C and N is related to topographic variation in temperature which is confounded with vegetation community. Data suggest that climatic changes will result in altered aboveground and soil C and N sequestration and fluxes.
Keywordsaboveground belowground C sequestration fluxes long-term data N sequestration pools
We thank the investigators of Coweeta LTER 3 (1990–1996) for contributions to the design of the original gradient study, the technicians and graduate students who have made measurements on these plots periodically throughout the last 20+ years, and Coweeta Analytical Lab managers, Dr. Barbara (Kitti) Reynolds, James Deal and Cindi Brown who have insured high quality control of all analyses. We also thank Drs. Rich Bowden and Luke Nave for helpful comments on the manuscript. This work was funded by NSF Grants DEB0218001 and DEB0823293 to the Coweeta LTER program at the University of Georgia and by USDA Forest Service, Southern Research Station, Coweeta Hydrologic Laboratory project funds. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the authors and do not necessarily reflect the views of the USDA Forest Service.
Compliance with Ethical Standards
Conflict of interest
The authors declare that experiments complied with the current laws of the USA and there is no conflict of interest.
- Cromack J, K., Monk CD. 1975. Litter production, decomposition, and nutrient cycling in a mixed hardwood watershed and a white pine watershed. In: Howell FG, Gentry JB, Smith MH, Eds. Mineral cycling in southeastern ecosystems proceedings. Augusta (GA): US Energy Research and Development Administration, pp 609–24.Google Scholar
- Crowley KF, McNeil BE, Lovett GM, Canham CD, Driscoll CT, Rustad LE, Denny E, Hallett RA, Arthur MA, Boggs JL, Goodale CL, Kahl JS, McNulty SG, Ollinger SV, Pardo LH, Schaberg PG, Stoddard JL, Weand MP, Weathers KC. 2012. Do nutrient limitation patterns shift from nitrogen toward phosphorus with increasing nitrogen deposition across the northeastern United States? Ecosystems 15:940–57.CrossRefGoogle Scholar
- Douglass JE, Hoover MD. 1988. History of Coweeta. In: Swank WT, Crossley DA Jr, Eds. Forest hydrology and ecology at Coweeta. New York: Springer. p 469.Google Scholar
- Fox S, Jackson B, Jackson S, Kauffmann G, Koester MC, Mera R, Seyden T, Van Sickle C, Chipley S, Fox J, Hicks J, Hutchins M, Lichtenstein K, Nolan K, Pierce T, Porter B. 2011. Western North Carolina report card on forest sustainability. Asheville, NC: USDA Forest Service, Southern Research Station. pp 1–198.Google Scholar
- Harmon ME, Bible K, Ryan MG, Shaw DC, Chen H, Klopatek J, Li X. 2004. Production, respiration, and overall carbon balance in an old-growth Pseudotsuga-Tsuga forest ecosystem. Ecosystems 7:498–512.Google Scholar
- Harmon ME, Franklin JF, Swanson FJ, Sollins P, Gregory SV, Lattin JD, Anderson NH, Cline SP, Aumen NG, Sedell JR, Lienkaemper GW, Cromack JK, Cummins KW. 1986. Ecology of coarse woody debris in temperate ecosystems. In: MacFadyen A, Ford ED, Eds. Advances in ecological research. Cambridge: Academic Press. p 133–302.CrossRefGoogle Scholar
- Hooper DU, Bignell DE, Brown VK, Brussard L, Mark Dangerfield J, Wall DH, Wardle DA, Coleman DC, Giller KE, Lavelle P. 2000. Interactions between aboveground and belowground biodiversity in terrestrial ecosystems: patterns, mechanisms, and feedbacks: we assess the evidence for correlation between aboveground and belowground diversity and conclude that a variety of mechanisms could lead to positive, negative, or no relationship-depending on the strength and type of interactions among species. BioScience 50:1049–61.CrossRefGoogle Scholar
- Jenny H. 1941. Factors of soil formation: a system of quantitative pedology. New York, NY: McGraw-Hill Book Company Inc.Google Scholar
- Knoepp JD, Swank WT, Haines BL. 2014. Long- and short-term changes in nutrient availability following commercial sawlog harvest via cable logging. In: Swank WT, Webster JR, Eds. Long-term response of a forest watershed ecosystem: clearcutting in the southern Appalachians. London: Oxford University Press. p 57–84.CrossRefGoogle Scholar
- NADP. 2017. (NRSP-3). National Atmospheric Deposition Program Office, Illinois State Water Survey, 2204 Griffith Dr., Champaign, IL 61820.Google Scholar
- SAS. 2013. SAS/STAT 9.3 User’s Guide. Cary, NC USA: SAS Institute Inc.Google Scholar
- Yount JD. 1975. Forest-floor nutrient dynamics in southern Appalachian hardwood and white pine plantations ecosystems. In: Howell FG, Gentry JB, Smith MH, Eds. Mineral cycling in southeastern ecosystems proceedings. Augusta, GA: U.S. Energy Research and Development Administration, p 898.Google Scholar