DISCLAIMER: This article is being kept online for historical purposes. Though accurate at last review, it is no longer being updated. The page may contain broken links or outdated information.
Origin of grasslands
Retallack, Gregory J. Department of Geological Sciences, University of Oregon, Eugene, Oregon.
- Paleosol and paleoclimate data
- Explanations for cooling
- Implications for the future
- Related Primary Literature
- Additional Reading
Grasslands are the foundation of agriculture, providing the grains and proteins for a hungry world. Forty million years ago (MYA), there were no well-drained grasslands. However, today grasslands occupy approximately 40% of the land area of our planet. Grasslands have been considered to be adapted to areas of diminished precipitation on the downwind side of topographic obstacles that are created by mountain uplift and the tectonic reorganization of ocean currents. Now, there is an alternative hypothesis: Grasslands were a biological force for global change through the coevolution of grasses and animals that eat mainly grasses (grazers), creating cooler and drier conditions because of the light color of the grasses, limited evaporation of water from plants into the atmosphere, and deep organic soils. Organisms in coevolutionary trajectories adapt to each other rather than to their environments, so they can be forces for global change. For example, humans are a force for global warming and, by ploughing and harvesting, they have undone the cooling effects of grasslands. However, carbon farming techniques can offset human-induced global warming.
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 10,000 highly qualified scientists and 46 Nobel Prize winners.
MORE THAN 8700 articles covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information