@article {Rockstrom2009Safe,
	title = {A safe operating space for humanity},
	journal = {Nature},
	volume = {461},
	number = {7263},
	year = {2009},
	month = {September},
	pages = {472{\textendash}475},
	publisher = {Nature Publishing Group},
	abstract = {Identifying and quantifying planetary boundaries that must not be transgressed could help prevent human activities from causing unacceptable environmental change, argue Johan Rockstr{\"o}m and colleagues.},
	keywords = {biodiversity, conservation, course, ecology, tippingpoints},
	issn = {0028-0836},
	doi = {10.1038/461472a},
	url = {http://dx.doi.org/10.1038/461472a},
	author = {Rockstrom, Johan and Steffen, Will and Noone, Kevin and Persson, Asa and Chapin, F. Stuart and Lambin, Eric F. and Lenton, Timothy M. and Scheffer, Marten and Folke, Carl and Schellnhuber, Hans J. and Nykvist, Bjorn and de Wit, Cynthia A. and Hughes, Terry and van der Leeuw, Sander and Rodhe, Henning and Sorlin, Sverker and Snyder, Peter K. and Costanza, Robert and Svedin, Uno and Falkenmark, Malin and Karlberg, Louise and Corell, Robert W. and Fabry, Victoria J. and Hansen, James and Walker, Brian and Liverman, Diana and Richardson, Katherine and Crutzen, Paul and Foley, Jonathan A.}
}
@article {Reich2009Elevated,
	title = {Elevated CO2 Reduces Losses of Plant Diversity Caused by Nitrogen Deposition},
	journal = {Science},
	volume = {326},
	number = {5958},
	year = {2009},
	month = {December},
	pages = {1399{\textendash}1402},
	abstract = {The interactive effects of rising atmospheric carbon dioxide (CO2) concentrations and elevated nitrogen (N) deposition on plant diversity are not well understood. This is of concern because both factors are important components of global environmental change and because each might suppress diversity, with their combined effects possibly additive or synergistic. In a long-term open-air experiment, grassland assemblages planted with 16 species were grown under all combinations of ambient and elevated CO2 and ambient and elevated N. Over 10 years, elevated N reduced species richness by 16\% at ambient CO2 but by just 8\% at elevated CO2. This resulted from multiple effects of CO2 and N on plant traits and soil resources that altered competitive interactions among species. Elevated CO2 thus ameliorated the negative effects of N enrichment on species richness. 10.1126/science.1178820},
	keywords = {biodiversity, course, diversity, ecology, species\_richness},
	doi = {10.1126/science.1178820},
	url = {http://dx.doi.org/10.1126/science.1178820},
	author = {Reich, Peter B.}
}
