Increasing atmospheric nitrogen deposition: implications for tallgrass prairie restoration
Abstract
Continued intensification of agriculture and combustion of fossil fuels will increase rates of atmospheric nitrogen (N) deposition over the next century. N is typically a limiting resource for terrestrial plants, and many species are adapted to low-N conditions. Increased N availability can affect both plant biomass and species composition, often favouring N-demanding, adventive species. These effects can be adverse in the context of ecological restoration, where the end product often relies on establishing a particular community composition. I used a field experiment in Norfolk County, Ontario, to examine how N addition affects species composition and plant productivity of a tallgrass prairie restoration. I predicted that N addition would increase the abundance of plant species not included in the original seeding. Contrary to my prediction, relative abundance of native, rather than adventive species, increased with N addition, although the latter species were scarce at the site, possibly as a result of dispersal limitation. I conclude that increased N availability can enhance the growth of tallgrass prairie species in the first few years of restoration.