Grassy Ecosystems in the Anthropocene

As the Anthropocene advances, there are few parts of Earth that have not been impacted by human influence. Humans have had a long-sustained interaction with grassy ecosystems, but they are becoming severely impacted by direct and indirect impacts as the Anthropocene advances. Grassy ecosystems are easy to clear and cultivate, poorly protected, and poorly defined due to legacies of colonial narratives that can describe them as deforested, wastelands, or derived. Climate change, land conversion, and the erosion of the processes that have shaped grassy ecosystems for millennia have had cascading and cumulative impacts on grassy ecosystem extent and integrity. We examine how these changes are impacting grassy ecosystems, more specifically, those that fall into ecosystem uncertain space—a climate envelope where vegetation is not at equilibrium with climate and either grassy or forest ecosystems can occur. It is within this space that climate, CO2, and disturbances (fire, herbivores) interact to determine the presence of grassy ecosystems. Changes to any of these components reduce the integrity of grassy ecosystems. The loss of these ancient biodiverse ecosystems means loss of an array of ecosystem services fundamental to the lives of more than 1 billion people alongside Earth system impacts of altered albedo, carbon, and hydrological cycles. Expected final online publication date for the Annual Review of Environment and Resources, Volume 47 is October 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.