Boundaries
As its name suggests, the most obvious features of the tallgrass prairie are tall grasses, such as indiangrass (Sorghastrum nutans), big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium), and switchgrass (Panicum virgatum), which average between 1.5 and 2 m (4.9 and 6.6 ft) tall, with occasional stalks as high as 2.5 to 3 m (8.2 to 9.8 ft). Prairies also include a large percentage of forbs, such as lead plant (Amorpha spp.), prairie rosinweed (Silphium terebinthinaceum), and coneflowers.
The tallgrass prairie biome depends upon prairie fires, a form of wildfire, for its survival and renewal. Tree seedlings and intrusive alien species without fire-tolerance are eliminated by periodic fires. Such fires may either be set by humans (for example, Native Americans used fires to drive bison and improve hunting, travel, and visibility) or started naturally by lightning. Researchers' attempts to re-establish small sections of tallgrass prairie in arboretum fashion were unsuccessful until they began to use controlled burns.
Technically, prairies have less than 5-11% tree cover. A grass-dominated plant community with 10-49% tree cover is a savanna.
Due to accumulation of loess and organic matter, parts of the North American tallgrass prairie had the deepest topsoil recorded. After the steel plough was invented by John Deere, this fertile soil became one of America's most important resources. Over 99% of the original tallgrass prairie is now farmland.
Read more about this topic: Tallgrass Prairie
Famous quotes containing the word boundaries:
“Ideas are not thoughts; the thought respects the boundaries that the idea ignores thereby failing to realize itself.”
—Franz Grillparzer (1791–1872)
“We love to overlook the boundaries which we do not wish to pass.”
—Samuel Johnson (1709–1784)
“Women’s art, though created in solitude, wells up out of community. There is, clearly, both enormous hunger for the work thus being diffused, and an explosion of creative energy, bursting through the coercive choicelessness of the system on whose boundaries we are working.”
—Adrienne Rich (b. 1929)