The role of different nitrogen forms in supporting productivity of North American grasslands

North American grassland productivity increases with increasing precipitation from west to east. Where do plants get the nitrogen to support this productivity? We looked at the changing availability of extractable inorganic and organic nitrogen across this gradient (Mobley et al. 2014 PLOS), as well as differences in the nitrogen reallocation ability of grasses from tallgrass, northern mixed grass, and shortgrass prairies (Matt Cleary, University of Wyoming MS thesis). Building on these results, and in collaboration with UWyo PhD student Cait Rottler, we are studying the ability of these grass species to assimilate organic N, and the relative importance of organic N in supporting productivity of these grasses.

Collaborators: Indy Burke, Matt Cleary, Cait Rottler

Nitrogen retention in current and former shortgrass prairie ecosystems.

Shortgrass prairie ecosystems are semiarid, often considered to be co-limited in their production by the availability of both water and nitrogen. As such, their nitrogen cycles tend to be closed, with very small inputs and outputs relative to pool sizes. Shortgrass ecosystems are subject to a variety of human management activities, from ranching to dryland wheat farming to coal and gas development. We are interested in how these management activities alter the N cycle, particularly if management causes these ecosystems to lose, or leak, more nitrogen. (Mobley et al. 2014 JEQ)

Collaborators: Indy Burke, Rebecca McCulley, Gary Peterson

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