Global Change and Grassland Systems

Global change is planetary scale changes in ecological or physical systems. Examples of these changes include increasing CO2 levels, climate change, decreasing biodiversity, urbanization and rising population, land degradation and desertification, among many more processes that have negative impacts on the environment.

Grassland ecosystems have in part become more widespread due to ecosystem changes such as altered disturbance regimes. Altered rainfall patterns can cause the natural climax vegetation to transition to grassland from forest at higher latitudes while deserts can move up from lower latitudes due to degradation and unsustainable human land uses. Additionally, grasslands often constitute some of the most fertile farmland, and as human populations increase, more grassland is likely to be converted to agriculture.

Ultimately, the most at-risk grasslands might be those that are threatened by desertification. Semi-arid lands are most fragile because the vegetation doesn't recover well after disturbance such as fire and grazing, especially if invasive species are also a threat. These problems will be complicated by projected decreases in precipitation in semi-arid areas, which could accelerate the desertification process by making it even more difficult for grasses to reestablish. The image below shows the desertification process over 100 years in Arizona, caused by unsustainable grazing practices and decreased precipitation patterns in a grassland.


Image: http://climatechange.lta.org/manage-grasslands/

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2880131/

http://www.who.int/globalchange/environment/en/