Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/6/2012
Publication Date: 2/13/2012
Publication URL: http://handle.nal.usda.gov/10113/58783
Citation: Gundale, M.J., Nilsson, M., Bansal, S., Jaderlund, A. 2012. The interactive effects of temperature and light on biological nitrogen fixation in boreal forests. New Phytologist. 194:453-463. DOI: 10.1111/j.1469-8137.2012.04071.x Interpretive Summary: Factors affecting nitrogen-fixation in boreal mosses can have considerable impact on plant productivity, which is critical to understanding the impacts of climate change on carbon sequestration in boreal forests. We evaluated how variation in temperature and light affect N-fixation by the common mosses Pleurozium schreberi and Hylocomium splendens. Nitrogen-fixation rates increased with temperature, but eventually declined at the highest temperature, particularly under high light conditions. These results suggest that climate warming may increase N-fixation in boreal forests, but the occurrence of extreme temperature events could limit increases.
Technical Abstract: • Plant productivity is predicted to increase in northern latitudes due to climate warming; however, this may depend on whether biological N-fixation also increases. We evaluated how variation in temperature and light affect N-fixation by two boreal feather mosses, Pleurozium schreberi and Hylocomium splendens, which are the primary source of N-fixation in most boreal environments. • We measured N-fixation rates two and four weeks after exposure to a factorial combination of normal, intermediate, and high temperature (16.3, 22.0, and 30.3 °C) and light (148.0, 295.7, and 517.3 µmol m-2 s-1) environments. • Our results showed that P. schreberi achieved higher N-fixation rates relative to H. splendens in response to warming treatments but that the highest warming treatment eventually caused N-fixation to decline for both species. Light strongly interacted with warming treatments, having positive effects at low or intermediate temperatures and damaging effects at high temperatures. • These results suggest that climate warming may increase N-fixation in boreal forests, but that increased shading by the forest canopy or occurrence of extreme temperature events could limit increases. They also suggest that P. schreberi may become a larger source of N in boreal forests relative to H. splendens as climate warming progresses