The grasslands are dominated by grasses (no surprise). There are other plants in them as well. Anyone who misses this on the test deserves to fail! The other plants are generally referred to as forbs . These are plants whose stems do not develop wooden trunks or stems, but instead remain soft and fleshy.
There are grasslands on most continents. In Africa and Australia they’re called savannas, steppes in Europe and Asia, and pampas in South America. In North America we called them Prairies.
Grassland biomes cover more of the Earth’s surface than any other biome.
North American Grasslands are divided into three smaller sections based on the height of the dominant grasses. There is a positive correlation between the height of the grasses and the amount of precipitation the region receives. At the eastern edge of the grasslands the average annual precipitation is about 30 inches. Moving west, the amount of precipitation decreases until finally, at the western edge of the grasslands adjacent to the desert, just over 10 inches of precipitation fall annually. Correspondingly, the grasses reach 8 to 10 feet tall in the tall grass prairies and in the short grass prairies the grasses only grow to 15 inches or so.
West Central East 30 20 10 Precipitation per Year (inches) Short Grass Mixed Grass Tall Grass Grass Height (feet) 1.5 10 Correlation between precipitation and prairie grass height.
The Grasslands experience distinctive seasons. During spring, the grasses are lush and green, photosynthetically productive, reproductive and growing.
By summer precipitation has waned, the grass leaves die and turn brown and their flower heads are left to drop seeds. Grasses are extremely important plants in food webs because unlike other plants, their leaves maintain their nutrient quality after they’ve died. This allows farmers to feed hay (dried stems and leaves of grasses) to livestock to sustain them through the winter. In natural ecosystems, grazers like bison, wildebeests, and zebra eat dead grass leaves as their staple diet.
Much of the North American Grasslands are cold, windy, and desolate during winter. Trees, barely visible in the background generally only grow along the margin of streams. Most North American Grassland animals migrate or hibernate during the winter months.
This grass is Big Blue Stem, also known as Turkey Foot. It grows to about 10 feet. You don’t have to travel west to see it. For some reason the Hamilton County Park District loves to plant little prairies. At Triple Creek Park, the field between the pond and Interstate 275 is planted as a prairie and the dominant plant is this grass species. During winter their leaves and stems are dead and brown but their size is apparent.
This is a Mixed Grass Prairie in autumn. The taller grasses are Switch Grass. Short grass species can be seen filling in the gaps between them.
This is a Short Grass Prairie. None of the grass species that dominate this landscape are more than 1.5 to 2 feet tall.
Grasses are Angiosperms (flowering plants). Their flowers are not showy. There are no brightly colored petals and no sweet smelling fragrances. Bees and butterflies are not attracted to them. Instead they produce copious amounts of pollen that is carried by the wind from one flower to another. Big Blue Stem’s three pronged flowers can be seen at the top of the plants on the left. The grass on the right is called Fox Tail. Its flower head droops under its own weight.
Earlier you were introduced to the term “forbs”. In late spring Grasslands have a diversity of them. They’re not as dominant as grasses but in this photograph you can certainly see that they’re important.
Where we live, in the Temperate Deciduous Forest biome, most of our native flowering plants are adapted to living in forests. They flower early in spring before the trees grow leaves and shade them out. If we plant those natives in our flower beds, we will enjoy flowers until May and then they would all be gone. Since our lawns are often open and sunny, and we want flowering plants all summer, we frequently choose flowering plants from the Grasslands. The following species are native to North American Grasslands. I (Mr. D) have lots of flower gardens in my yard and many of these plants are growing in them. As long as the plants are given water, they will be tricked into “thinking it’s still the growing season”. If they aren’t watered, their flowers and leaves, but not their roots, will die. The following photos show some spectacular North American Grassland forbs.
Grasses are very productive. They support a great diversity of primary consumers.
Several species of toads inhabit grasslands to feed on the bounty of grass eating insects. This is the Great Plains Toad
Grassland squirrel species are numerous. There are no trees for them to climb. They’ve adapted by burrowing. They’re called ground squirrels. This is Franklin’s Ground Squirrel.
This is the Thirteen-lined Ground Squirrel. It has a great scientific name, Spermophilus tridecimliniatus . Sperm = seed; philus = to love; tri = 3; deci = 10; lineatus = lines. Translation – “13 lined seed lover” This species has invaded Ohio where grasses are cut low in big open spaces like parks and golf courses. Some of you may have encountered it at Joyce Park in Fairfield where it inhabits the low grassy soccer fields.
Winter conditions in the Grasslands are far too harsh for ground squirrels to remain active. They are hibernators. They have the ability to lower their body temperature but maintain it above freezing. Their heart slows from 150 beats per minute to perhaps five beats and they draw one or two breaths per minute. They will maintain this lowered metabolic rate for 5 or 6 months until warm weather returns. They eat grass seeds all summer to fatten up. This fat has to last them through the winter.
Ground squirrels have several predators. This Badger’s long, thick front claws and short, powerful front limbs allow it to dig ground squirrels right out of their burrows.
He’s either being aggressive or smiling for the camera.
Prairie Dogs are also ground squirrels. Unlike other ground squirrel species, Prairie Dogs are social. They live in colonies called Prairie Dog Towns. A few stand as sentinels while the others graze on grass seeds. When predators approach, the sentinels “bark” to warn the others. The bark, hence the name Prairie Dog . Cattle ranchers hate these little rodents because they dig burrows that their cattle step into, breaking their legs. To combat this, ranchers set out poisoned seeds to kill off entire Prairie Dog Towns.
This is a Black-footed Ferret. Their sole food source is Prairie Dogs. As ranchers eliminated Prairie Dog towns en masse, the Black-footed Ferret’s population declined dramatically. At one point there were only 21 of them left. It is now a federally endangered species and although its gene pool is limited, the species has made a recovery. Prairie Dog towns are now protected as a means of protecting this little weasel.
Just because there are no trees, doesn’t mean there are no owls. These are Burrowing Owls. They inhabit Short Grass Prairies where they can stand on the edge of the Prairie Dog burrow they take over to watch for the small rodents they eat. These owls do not (cannot) dig their own burrows. While most owls are nocturnal, this species is diurnal.
Prairie birds are species that require wide open spaces. This is a Meadow Lark. It lives in pastures in Ohio but if the pasture undergoes succession and trees move in, the Meadow Larks leave by the time the trees are knee high. This species is an insectivore. It migrates to Central America during winter when insects are unavailable in the North American Grasslands.
This is a Prairie Chicken, a Short Grass Prairie inhabitant. It is not migratory. It is able to scratch through the snow in winter to find grass seeds. During warm seasons it also eats insects. A female walks into a circular arena called a Lek where as many as twenty males puff out their yellow throat skin, let out loud booming calls, and do elaborate dances. The best dancer wins the female. The others remain at the Lek and wait for the next female. If you want to see the males bust a move go to…. http://www.youtube.com/watch?v=s2_wdMmEupQ&feature=related
Food chain in action. This Golden Eagle (much larger than a Bald Eagle) is about to capture a Red Fox. The fox feeds on rodents like ground squirrels. Short Grass Prairies are widely used for sheep ranching. This bird of prey is not a friend of sheep ranchers. It frequently captures and carries off lambs.
Along with Badgers, Coyotes are important grassland animals because they’re proficient diggers. Their abandoned burrows are used by many other species.
Prairies are riddled with shallow wetlands called pothole lakes . They are essential habitat for tens of thousands of ducks. These are duck species that feed on the abundant seeds of grasses and forbs.
Grasslands are home to many reptiles. This is a Prairie Rattlesnake. Biologists believe rattlesnakes evolved in the grasslands where the dry, overlapping skin on their tail that forms the rattle gave them the ability to warn hooved animals such as bison, of the snake’s presence. Domestic cattle react the same way wild cows (bison) react to the buzzing of a rattlesnake’s rattle. Both stop in their tracks, then move backwards away from the source of the sound. This snake species eats ground squirrels.
This large snake is called a Gopher Snake. Ground squirrels, also known as gophers, are its staple food. Gopher Snakes did not evolve to have a rattle on their tail to warn other animals of their presence. Instead they have loose flap of tissue inside their mouth. When they exhale air rapidly over that tissue a very loud hissing noise is produced. It effectively scares away most predators such as weasels, coyotes and foxes. I’ve heard Gopher Snakes hiss. It is quite startling. This species grows up to 7 or 8 feet in length.
Grasslands are very productive. On each continent there are large grazers that help control the grass populations. In North America it’s the Bison. In Africa Wildebeests and Zebras fill that niche. In Australia, Kangaroos are the grazers. These animals are unrelated but have evolved the tools to accomplish the same job. They are called ecological equivalents .
This is a Jack Rabbit. It’s actually a hare, not a rabbit. Rabbits give birth to blind, naked, helpless babies. Female hares have a longer pregnancy which allows the embryos to develop further before birth. Baby hares are born fully cloaked in fur, their eyes and ears are open, and they have a full set of teeth. They nurse from their mother only for a couple of days to build their immune system before setting off on their own. With few places to hide, the giant ears allow Jack Rabbits to hear potential predators and in the heat of the day, they work like radiators to cool the hare’s blood. Notice how well the color camouflages the hare with the grasses. These are big. 10 to 12 pound is normal. Our local cottontail rabbits might weigh 2 pounds.
Grassland ecology is maintained by fire. During summer, after the grass leaves dry, lightning strikes set the plants ablaze. If these fires don’t happen, the dead grasses from previous years for a dense mat. If this mat becomes too thick and dense is becomes difficult for new grasses to grow up through it. Likewise small animals get tangled in the mat of vegetation. When fires burn the grass mat, the ashes return their nutrients to the soil. Prairie fires burn fast. They’re not like forest fires. A few acres can burn in a couple of minutes. Birds obviously can fly away and larger mammals can move away from it. Small mammals, reptiles, and other small mammals simply retreat into their burrows. Since heat rises, no harm is done to those taking refuge below ground. Plants cannot flee the fire. During the evolution, grassland plants had to adapt to it.
..........AppDataLocalMicrosoftWindowsTemporary Internet FilesContent.IE5TLIFK4AYCopy_of_prairie_root_line_drawing.jpg Prairie plants are adapted to fire by having root systems that grow deep into the soil. Roots remain alive even when the leaves dry up and die or burn away. New leaves sprout from those roots to re-establish the grassland vegetation.
Grassland soils are thick and rich. The gross primary productivity of this biome is very high compared to others. In order to provide nutrients and minerals for such productive plants, the soil must be rich. Unfortunately man learned about the soils’ productivity and recognized that because it is so good for native prairie grasses, it is probably just as suitable for non-native grasses. About 99% of North American Grasslands have been converted to agriculture. Corn and wheat (both grasses) are farmed extensively where there once were native prairies. Lost with the prairies is much of the diverse plants and animals that inhabited them.
Enormous agricultural corporations have purchased land that was once native prairie and with their financial resources they use machines to do the work that thousands of humans could do. The North American Grasslands were acquired as the Louisiana Purchase. In this photo, corn is being harvested.
Those amber waves of grain that we learned to sing about in elementary school are tens of thousands of square miles of wheat. They were once our Grasslands, but today they support few of the plants and animals they once provided for.
Herds of bison have been replaced by herds of domestic cattle.
Historic photographs like this show that ranchers put herds of sheep that are much larger than herds of native grazers on the prairies. This many sheep clip grasses to the ground faster than they can reproduce. They’ve caused irreparable damage to the Short Grass Prairies of the American west.