Variation in foliar nitrogen and albedo in response to nitrogen fertilization and elevated CO2
- 484 Downloads
Foliar nitrogen has been shown to be positively correlated with midsummer canopy albedo and canopy near infrared (NIR) reflectance over a broad range of plant functional types (e.g., forests, grasslands, and agricultural lands). To date, the mechanism(s) driving the nitrogen–albedo relationship have not been established, and it is unknown whether factors affecting nitrogen availability will also influence albedo. To address these questions, we examined variation in foliar nitrogen in relation to leaf spectral properties, leaf mass per unit area, and leaf water content for three deciduous species subjected to either nitrogen (Harvard Forest, MA, and Oak Ridge, TN) or CO2 fertilization (Oak Ridge, TN). At Oak Ridge, we also obtained canopy reflectance data from the airborne visible/infrared imaging spectrometer (AVIRIS) to examine whether canopy-level spectral responses were consistent with leaf-level results. At the leaf level, results showed no differences in reflectance or transmittance between CO2 or nitrogen treatments, despite significant changes in foliar nitrogen. Contrary to our expectations, there was a significant, but negative, relationship between foliar nitrogen and leaf albedo, a relationship that held for both full spectrum leaf albedo as well as leaf albedo in the NIR region alone. In contrast, remote sensing data indicated an increase in canopy NIR reflectance with nitrogen fertilization. Collectively, these results suggest that altered nitrogen availability can affect canopy albedo, albeit by mechanisms that involve canopy-level processes rather than changes in leaf-level reflectance.
KeywordsAlbedo Nitrogen Leaf structure Nitrogen fertilization Free air CO2 enrichment
We thank G. James Collatz for helpful comments on a draft of this manuscript, Rob Braswell for providing the SAIL-2 model code, and Richard Norby, Colleen Iversen, and Jeffery Warren for support at ORNL. We are indebted to Michael Eastwood, ER-2 pilots Denis Steel, Tim Williams, and the rest of the AVIRIS team for aircraft data acquisition. This work was funded by a grant from the North American Carbon Program (NACP) NASA’s Terrestrial Ecology and Carbon Cycle Science Programs and a graduate fellowship provided by the Research and Discover program. The ORNL FACE experiment was supported by the US Department of Energy, Office of Science, Biological and Environmental Research Program. A.D.R. and M.K.B. acknowledge support, through the Harvard Forest REU program, from the National Science Foundation (Grant DBI-04-52254).
- Brooks TJ, Wall GW, Pinter PJ Jr, Kimball BA, LaMorte RL, Leavitt SW, Matthias AD, Adamsen FJ, Hunsaker DJ, Webber AN (2000) Acclimation response of spring wheat in a free-air CO2 enrichment (FACE) atmosphere with variable soil nitrogen regimes. 3. Canopy architecture and gas exchange. Photosynth Res 66:97–108PubMedCrossRefGoogle Scholar
- Field C, Mooney HA (1986) The photosynthesis-nitrogen relationship in wild plants. In: Givinsh TI (ed) On the economy of form and function. Cambridge University Press, Cambridge, pp 25–55Google Scholar
- Hollinger DY, Ollinger SV, Richardson AD, Meyers TP, Dail DB, Martin ME, Scott NA, Arkebauer TJ, Baldocchi DD, Clark KL, Curtis PS, Davis KJ, Desai AR, Dragoni D, Goulden ML, Gu L, Katul GG, Pallardy SG, Paw UKT, Schmid HP, Stoy PC, Suyker AE, Verma SB (2010) Albedo estimates for land surface models and support for a new paradigm based on foliage nitrogen concentration. Glob Change Biol 16:696–710CrossRefGoogle Scholar
- Malenovský Z, Martin E, Homolová L, Gastellu-Etchegorry J-P, Zurita-Milla R, Schaepman ME, Pokorný R, Clevers JGPW, Cudlín P (2008) Influence of woody elements of a Norway spruce canopy on nadir reflectance simulated by the DART model at very high spatial resolution. Remote Sens Environ 112:1–18CrossRefGoogle Scholar
- Ollinger SV, Richardson AD, Martin ME, Hollinger DY, Frolking S, Reich PB, Plourde LC, Katul GG, Munger JW, Oren R, Smith ML, Paw UKT, Bolstad PV, Cook BD, Day MC, Martin TA, Monson RK, Schmid HP (2008) Canopy nitrogen, carbon assimilation and albedo in temperate and boreal forests: functional relations and potential climate feedbacks. Proc Nat Acad Sci 105:19335–19340CrossRefGoogle Scholar
- Riggs JS, Tharp ML, Norby RJ (2009) ORNL FACE CO2 data. carbon dioxide information analysis center, Oak Ridge, TN, USA. http://cdiac.ornl.gov. Accessed 15-July-2010
- Sánchez J, Canton MP (1999) Space imaging processing. CRC Press LLC, Boca RatonGoogle Scholar
- Tari DB, Gazanchian A, Pirdashti HA, Nasiri M (2009) Flag leaf morphophysiological response to different agronomical treatments in a promising line of rice (Oryza sativa L.). Am-Euras J Agric Environ Sci 5:403–408Google Scholar
- Wright IJ, Reich PB, Westoby M, Ackerly DD, Baruch Z, Bongers F, Cavender-Bares J, Chapin T, Cornelissen JHC, Diemer M, Flexas J, Garnier E, Groom PK, Gulias J, Hikosaka K, Lamont BB, Lee T, Lee W, Lusk C, Midgley JJ, Navas M-L, Niinemets U, Oleksyn J, Osada N, Poorter H, Poot P, Prior L, Pyankov VI, Roumet C, Thomas SC, Tjoelker MG, Veneklaas EJ, Villar R (2004) The worldwide leaf economics spectrum. Nature 428:821–827PubMedCrossRefGoogle Scholar
- Zhang Q, Xiao X, Braswell BH, Linder E, Ollinger S, Smith ML, Jenkins JP, Baret F, Richardson AD, Moore B III, Minocha R (2006) Characterization of seasonal variation of forest canopy in a temperate deciduous broadleaf forest, using daily MODIS data. Remote Sens Environ 105:189–203CrossRefGoogle Scholar