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Warming prevents the elevated CO₂-induced reduction in available soil nitrogen in a temperate, perennial grassland
- HOVENDEN, MARK J., NEWTON, P.C.D., CARRAN, R.A., THEOBALD, P., WILLS, K.E., VANDER SCHOOR, J.K., WILLIAMS, A.L., OSANAI, Y.
- Global change biology 2008 v.14 no.5 pp. 1018-1024
- dissolved organic nitrogen, carbon dioxide, terrestrial ecosystems, carbon dioxide enrichment, ion exchange, soil, carbon, emissions, ammonium nitrate, grasslands, climate
- Rising atmospheric carbon dioxide concentration ([CO₂]) has the potential to stimulate ecosystem productivity and sink strength, reducing the effects of carbon (C) emissions on climate. In terrestrial ecosystems, increasing [CO₂] can reduce soil nitrogen (N) availability to plants, preventing the stimulation of ecosystem C assimilation; a process known as progressive N limitation. Using ion exchange membranes to assess the availability of dissolved organic N, ammonium and nitrate, we found that CO₂ enrichment in an Australian, temperate, perennial grassland did not increase plant productivity, but did reduce soil N availability, mostly by reducing nitrate availability. Importantly, the addition of 2 °C warming prevented this effect while warming without CO₂ enrichment did not significantly affect N availability. These findings indicate that warming could play an important role in the impact of [CO₂] on ecosystem N cycling, potentially overturning CO₂-induced effects in some ecosystems.