Novel Relationship Between Nitrogen and Albedo (Solar Radiation Reflectance) in Forests
A positive correlation between the uptake of nitrogen and carbon by leaves has been recognized for some time. However, in a study published this week in the Proceedings of the National Academy of Sciences, scientists report that this relationship also holds for whole forest canopies and that both variables are strongly related to canopy albedo (the fraction of solar radiation that is reflected). This suggests that nitrogen levels in forests can influence Earth’s climate in ways that have not previously been recognized. The article reports that forests with high levels of foliar nitrogen reflect more solar radiation and absorb more CO2 than forest with lower nitrogen levels. They also discovered that variation in forest canopy nitrogen can be accurately detected using satellites, making it possible to continuously track these global-scale effects of forests on the Earth’s climate system. Significant data for these analyses was provided by DOE-funded AmeriFlux sites.
S.V. Ollinger, A.D. Richardson, M.E. Martin, D.Y. Hollinger, S. Frolking, P. B. Reich, L.C. Plourde, G.G. Katul, J.W. Munger, R. Oren, M-L. Smith, K.T. Paw U, P. V. Bolstad, B.D. Cook, M.C. Day, T.A. Martin, R.K. Monson, and H.P. Schmid (2008) Canopy nitrogen, carbon assimilation, and albedo in temperate and boreal forests: Functional relations and potential climate feedbacks. ww.pnas.org/cgi/doi/10.1073/pnas.0810021105