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Mixed-grass prairie

Grasslands are plant communities dominated by herbaceous (non-woody species) grasses and forbs. Grasslands are found throughout the world. Areas of grasslands smaller than a beach towl can easily contain over 30 species of plants. However, the majority of the foliar plant biomass (dry weight of leaf tissue) is typically associated with a few grass species. Generally, grasslands receive low to intermediate amounts of rainfall limiting establishment and growth of tree species. Savannas are an exception and have trees intermixed with grasslands. This mixture is often maintained by fire and grazing.

There are three major sub-divisions of the Great Plains: tall grass prairie, mixed-grass prairie, and short grass prairie. Different sources tend to place mixed- and short grass prairies in different places leading to some confusion. There are numerous variations of these three types. The descriptions are typically based on the two or three most common species. There are also numerous other types of grasslands beyond those in the Great Plains discussed here on other pages including: alpine, old fields, grassy balds, Palouse prairie, and wet prairie and this is not an exhaustive list.

Unlike forests, grasslands store most of the carbon they fix through photosynthesis belowground in root tissue. Although drier habitats fix less carbon via photosynthesis, they generally allocate more to roots than shoots relative to wetter habitats. In some dry grasslands, 10 to 20 times more carbon is allocated belowground than aboveground. Although some grasslands have been converted into farmland, vast grasslands remain and function as rangelands, a type of agriculture. Rangelands provide a balance between maintaining natural ecosystems while providing meat products for human consumption. However, most beef products that arrive at your grocery store likely spent their last year or so consuming corn (being "finished") to attain the meat quality expected by consumers.

Pictures illustrate the landscape, plants, and wildlife (Greater sage-grouse, prairie dog, etc.) associated with mixed-grass prairie at or near where I work in Miles City, (eastern) Montana.

Large expansive areas of shortgrass and mixed-grass prairies still exist in the western portion of Great Plains of the United States. These grasslands are often relatively intact. Luckily these grasslands are generally too inhospitable for conversion to row crops because of low and/or infrequent rainfall. Where I live in Montana, we are surrounded by approximately a 100 mile radius of relatively intact mixed-grass prairie supporting a number of plants and animals.

The Great Plains have seen some major changes since the arrival of Europeans. Besides the most obvious transformation of grasslands to farmland, the two second most noteable are that migrating buffalo herds have been replaced by managed livestock and fire is often suppressed. Yet many of these grasslands function more or less as they did prior to European settlement.

Tall grass prairie, forming the eastern portion of the Great Plains, has been mostly replaced by farmland. This region is the breadbasket of the United States. As a society, we will have to decide how best to manage both our appetites for food (and biofuel) and natural places.

The delicate flower to the left is naked broomrape (Orobanche fasciculata). This plant is an obligate parasite and acquires all of its carbon by parasitizing other plants like the Artemisia frigida shown surrounding it. Most of the plant is belowground and it only emerges to flower.

Antelope roaming across grasslands (above right).

There are some well documented examples of poisinous insects acquiring their toxins from the plants that they consume... The picture above shows a caterpillar consuming the flowers of death camas (Zigadenus venenosus), a plant poisinous to cattle and humans but appartently not this caterpillar. To see a time-lapse movie of the scene to the right click this link.