AY Honor Temperate Grasslands Answer Key
Skill Level
1
Year
2023
Version
27.12.2024
Approval authority
North American Division
1
As the name implies, a grassland is a terrestrial biome where grasses (poaceae) are the dominant vegetation. While there is no agreed upon measurement, grasslands generally have less than 10-40% tree and shrub cover. Some definitions consider a grassland with less than 10-20% tree/shrub cover a prairie, while those with 20-40% tree/shrub cover would be a savanna. Grasslands are also often characterized by relatively low rainfall and seasonal fires.
1a
Grasslands can be found in temperate and tropical environments on all continents aside from Antarctica, usually as an intermediate zone between deserts and woodlands or forests. Large grasslands include the Shortgrass and Tallgrass prairies of North America, the steppes of Eurasia, the Puszta of Hungary, the Veldt of South Africa, and the Pampas of South America, as well as the tropical Savannas of Africa and India.
1b
A grassland needs sufficient water for the grasses and small plants to grow, but not enough water to support larger vegetation like shrubs and trees. Grasslands also frequently need either regular grazing or cyclical fires to suppress the growth of larger shrubs and plants.
1c
Grasslands are areas of high biodiversity, capture and store large amounts of carbon, provide areas of food, agriculture, and recreation, and assist in erosion control. By some accounts, a 100 acre grassland may have as many as 200 native species of plants, demonstrating their rich biodiversity.
1d
There are several ways to describe different grasslands.
Tropical grasslands include the vast African savannas, the smaller Indian savannas and Australian semi-arid grasslands. Like all grasslands, tropical grasslands are characterized by particular dominant grasses, but tropical grasslands also rarely or never experience frost, and often have distinct wet and dry seasons and nearly annual cycles of fire.
Temperate grasslands include the prairies of North America, the short grass steppes of Eurasia, the humid pampas of South America, the South African veldt, and the Hungarian pustza. Temperate grasslands endure hot summers and cold winters, both of which can stress plant (and animal) life. They usually receive 10-30 inches of rain a year, and fires, while an important part of the temperate grassland biome, are not as pronounced as in the tropical grasslands. Temperate grasslands often have very rich soil due to centuries of decaying plant matter.
In North America, there are the shortgrass prairies further west (with lower rainfall) and the tall grass prairies further east. Between the two are the mixed grass prairies, with the line between the three shifting depending upon weather and climate over the years. Shortgrass prairies are dominated by buffalograss (Buchloe dactyloides) and blue grama (Bouteloua gracilis), while tallgrass prairies are dominated by the "big four" - big bluestem (Andropogon gerardii), switchgrass (Panicum virgatum), indiangrass (Sorghastrum nutans), and little bluestem (Shizachyrium scoparium).
Other ways of dividing grasslands into differing ecosystems focus on rainfall, ground cover, and the amount of taller shrubs and trees. For example, glades and barrens are rocky grasslands, with incomplete ground cover, on arid, poor soils. Sand barrens are grasslands in poor sandy soil. Meadows are grasslands near streams and ponds, with ample water, while bogs and fens are at times considered part of grasslands, despite the limited grass present.
2
Poaceae (the grass family) - Wind-pollinated monocots that can grow from the base, rather than the tip, allowing continued growth after grazing or mowing.
Buffalograss (Buchloe dactyloides)
Blue Grama (Bouteloua gracilis)
Yellow Indiangrass (Sorghastrum nutans)
Little Bluestem (Schizachyrium scoparium)
Switchgrass (Panicum virgatum)
Apocynaceae (the dogbane family) - Plants in the dogbane family are characterized by flowers with five united petals and five united sepals. Within this large family are the milkweeds, common plants of southwestern grasslands, and critical plants for migrating Monarch butterflies.
Antelope Horns (Asclepias asperula) - Apocynaceae family
Zizotes Milkweed (Asclepias oenotheroides) - Apocynaceae family
Asteraceae (the sunflower family) - Dicot plants with composite flowers made up of ray and disc flowers.
Firewheel (Gaillardia pulchella) - Asteraceae family
Coreopsis (Coreopsis sp.) - Asteraceae family
Mexican Hat (Ratibida columnifera) - Asteraceae family
Fabaceae (the pea/legume family) - The flowers are often bilaterally symmetrical (zygomorphic), with uneven sized petals, though in some species flowers may be radially symmetrical. Leaves are often compound.
Texas Bluebonnet (Lupinus texensis) - Fabaceae family
Two-leaved Senna (Cassia roemeriana) - Fabaceae family
Lamiaceae (the mint family) - The Lamiaceae have squared (four-sided) stems, with flowers usually in whorls.
Purple Horsemint (Monarda citriodora) - Lamiaceae family
Mealy Blue Sage (Salvia farinacea) - Lamiaceae family
Solanaceae (the nightshade family) - The nightshades are characterized by flowers with five fused petals and a berry-like fruit. Nightshades are often toxic, though their edible members include tomatoes, potatoes, and eggplants.
Silver-Leaf Nightshade (Solanum elaeagnifolium) - Solanaceae family
Western Horse-Nettle (Solanum dimidiatum) - Solanaceae family
Verbenaceae (the vervain family) - Members of the vervain family frequently have squared stems (similar to their relative the Lamiaceae), with clusters or spikes of multiple small flowers.
Prairie Verbena (Verbena bipinnatifida) - Verbenaceae family
Texas Vervain (Verbena halei) - Verbenaceae family
3
To acquire your model for drawing, gently pull a grass plant from the ground, holding near the base of the plant. You can gently shake off the dirt from the roots, or use water. Lay the grass plant down on a clean surface and sketch. Alternatively, you can hang the grass to dry, and use the dried specimen for your drawing model. Some useful grass terminology to keep in mind: in grasses, the vertical “stem” is called a CULM, the “leaf” is a BLADE, the lower part of the blade that wraps around the culm is the SHEATH. The joints in a grass culm are called NODES. A horizontal grass stem that runs above ground, giving rise to new plants at nodes, is called a STOLON, whereas a horizontal stem underground is a RHIZOME. The flowering structure of a grass is an INFLORESCENCE. Many of these features are important in distinguishing between grass species while in the field.
The anatomy of a grass plant (Poa annua)
4
Temperate grassland are divided into two broad groups based on the average height of the grass. Shortgrass prairies usually receive lower amounts of rainfall, and are dominated by grasses that rarely reach much about 10 inches in height (ie Buffalograss and and Blue Grama). Tallgrass prairies receive more rainfall, with grasses that may reach 6 to 8 feet in height or more, including Big Bluestem, Little Bluestem, Yellow Indiangrass and .Switchgrass. In North America, the shortgrass prairies are usually further west that the tallgrass prairies, with a band of mixed grass prairies intermediate between the two.
Another bilateral categorization of temperate grasslands is based on the percent of shrub and see cover - prairies have less than 10-20 percent tree cover, savannas have 20-40 percent tree cover. (This is an alternate use of the term savanna, which also often refers to tropical grasslands). A prairie can evolve into savanna if there is insufficient grazing or fire, or an increase in available water. A savanna that does not have sufficient fire or grazing can evolve into a woodland or forest. A major fire can so damage a forest that it reverts back to a prairie, and significant fire, drought, or new grazers can see a savanna turned back into a prairie. These processes are referred to as ecological succession, where one ecosystem changes into another due to altered circumstances or natural processes.
5
The main reasons trees do not grow in grasslands are low rainfall and physical stress, such as grazing and seasonal fires. Shrubs and trees will frequently encroach upon prairies when fires are suppressed or grazers are removed.
The relationship between Prairies, Savannas, and Woodlands, based on fire and grazing, can be seen in this piece of a display at the Lady Bird Johnson Wildflower Center in Austin, TX, which has several small research grassland plots testing different combinations of fires and mowing on grassland development.
The relation between prairies, savannas, and woodlands, and the role of grazing and fire
6
6a
Plant adaptations to grasslands include low water needs, different methods of seed dispersals, quick early blooming (before the grasses get tall), and physical barriers to grazing, among others. Grasses store most of their reserve energy in their roots, allowing them to be protected from fire, as well as winter die-back. Many grasses grow from the base up, not from the tip out, so they can survive repeated grazing (or mowing). Grasses have numerous strategies to spread their seeds (from windblown to dropping nearby the parent), and many have phsical characteristics that protect them from predation, including fine hairs. Flowers like the Prairie Iris and Green Lily grow from bulbs that can lay dormant through winter, storing their energy below ground. The White Prickly Poppy , as its name implies, is covered in spines, protecting it from grazers. Texas Indian paintbrush is hemiparasitic, with its roots at times drawing nutrition from the grass roots in the prairie. Both the Horse Crippler and Prickly Pear are cacti, adapted to low water conditions common in southern prairies. And the Devil’s Claw, Spreading Hedge Parsley, and Common Cocklebur each have features on their seeds and seed pods that allow them to be carried by passing animals (or hikers).
Native bunch grasses recovering from a controlled fire
Grasses store their energy in their roots, protecting them from winter and grazing
Japanese Brome (Bromus japonicus) showing protective hairs on Culm and Blade
Prairie Iris (Alophia drummondii)
Green Lily (Schoenocaulon texanum)
White Prickly Poppy (Argemone albiflora)
Texas indian Paintbrush (Castilleja indivisia)
Horse Crippler (Echinocactus texensis)
Prickly Pear Cactus (Opuntia sp.)
Devil's Claw (Proboscidea louisianica)
Spreading Hedge Parsley (Torilis Arvensis)
Common Cocklebur (Xanthium strumarium)
6b
Birds are often adapted to the grasslands by the food they eat (seeds or insects), their nondescript coloration, or their nesting habits. Many birds also use the grasslands as their feeding and rest areas during long migrations. The Cattle Egret follows larger grazers in the grasslands, eating the insects they stir up. Sandhill Cranes feed in grasslands, and use them on their migration between the Arctic and Subtropics. The Loggerhead Shrike hunts insects, reptiles, and other small animals, at times skewering them on thorns to cache for later. Song and Savannah Sparrows have simple coloration that blends into the grasslands, while the painted bunting shows off bright colors, but prefers eating grass seeds. The Western Meadowlark is a ground nester, finding small depressions among the grass or brush, while the Dickcissel builds its nest close to the ground, weaving together grasses. The Scissor-Tailed Flycatcher hunts insects over the prairies, at times hovering in place, taking advantage of its long tail wings.
Cattle Egret (Bubulcus ibis)
Sandhill Crane (Grus canadensis)
Loggerhead Shrike (Lanius ludovicianus)
Song Sparrow (Melospiza melodia)
Savannah Sparrow (Passerculus sandwichensis)
Painted Bunting (Passerina ciris)
Western Meadowlark (Sturnella neglecta)
Scissor-Tailed Flycatcher (Tyrannus forficatus)
Dickcissel (Spiza americana)
6c
Mammal adaptations to grasslands include coloration, speed, feeding patterns, and adaptability. Pronghorn are the fasted land mammal in North America, able to outrun most any predator. The American Bison, North America’s largest land animal, once wandered the plains in the tens of millions, constantly shifting location to avoid overgrazing any one area. Mule Deer and White-Tailed Deer graze in the grasslands, able to leap and run quickly if predators are around. Rabbits and Jackrabbits also leap and turn quickly to avoid predators, both are able to conserve water, and both are colored to blend in to their environment. In more arid grasslands, the Jackrabbit’s long ears serve as radiators, letting off excess heat. Prairie Dogs dig extensive tunnels to hide, and primarily eat grass, drawing nearly all the water they need from the grasses, and thus not needing to be around streams or ponds. Coyotes have colors that blend in with the tall grasses, and are very adaptable in what they eat. Bobcats are normally found in woodlands and river bottoms, but also hunt in grasslands, seeking rabbits, rodents and other small mammals.
Pronghorn (Antilocapra americana)
American Bison (Bison bison)
Mule Deer (Odocoileus hemionus)
White-Tailed Deer (Odocoileus virginianus)
Black-Tailed Jackrabbit (Lepus californicus)
Eastern Cottontail (Sylvilagus floridanus)
Black-Tailed Prairie Dog (Cynomys ludovicianus)
Coyote (Canis latrans)
Bobcat (Lynx rufus)
6d
There are many interesting insect adaptations to live in grasslands, often related to what they eat or how they protect themselves. Dung Beetles eat and nest in animal dung, some rolling it into balls, others digging tunnels under dung piles, and still others just dwelling in the piles where they land. Leaf-Cutting Ants harvest grasses and plants, using them to grow fungus for food. Immature Froghoppers build protective “nests” of spit to protect themselves from predators. Honey Bees, Bumble Bees, and Carpenter Bees all feed off of the wildflowers in prairies, and have stingers as a defense mechanism. Numerous butterflies feed in the prairies. The Monarch caterpillars feed on milkweeds, leaving the butterflies toxic to predators (their bright coloration is a warning), the caterpillars of the Variegated Fritillary are one of the list picky, eating a wide variety of species, and the American Snout seems to detect when a major rainfall event may come after a drought, emerging in large numbers nearly simultaneously. Katydids and grasshoppers are able to leap (and fly), avoiding predators, while various Robber Flies use the prairies to hunt other insects.
Dung Beetle (Canthon imitator)
Texas Leaf-Cutting Ant (Atta texana)
Spittlebug [Froghopper] (Prosapia sp.)
Western Honey Bee (Apis mellifera)
Southern Plains Bumble Bee (Bombus fraternus)
Eastern Carpenter Bee (Xylocopa virginica)
Monarch Butterfly (Danaus plexippus)
Variegated Fritillary (Euptoieta claudia)
American Snout (Libytheana carinenta)
Fork-Tailed Bush Katydid (Scudderia furcata)
Bird Grasshopper (Schistocerca sp.)
Robber Fly (Diogmites sp.)
7
Much of a grass plant is in the underground roots and rhizomes, and as these decay, they release nutrients into the soil. Temperate grassland soils are also enriched by the annual cycle of dying grass leaves and stems, and by nutrients from the waste of animals that graze on grassland plants. Seasonal fires also rapidly replenish nutrients by quickly breaking down dead grasses and other plants.
8
You can look at large grasslands, but it may be more applicable to focus on a particular grassland in your local area. There are several national, state, and even city parks that include native or restored grasslands, and some local parks or universities may have “pocket prairies” that can serve as a way to study a grassland in your own locale. Many of these have informative displays on site, or have small booklets available in hard copy or online providing additional information. It may also be useful to interview a ranger or park volunteer. There are several services that collect historical weather and climate data you can use to study your grassland. Examples below look at two temperate grasslands, one a national grassland (Caddo-LBJ National Grasslands), the other a restored grassland in a local park (Commons Ford Ranch Metropolitan Park).
8a
Caddo/LBJ - 38,186 acres, spread across three counties in north central Texas
Commons Ford - 40 acres of restored prairie
8b
Caddo/LBJ - 63.5 degrees mean annual temperature, 35-55 in the winter, 75-95 in the summer
Commons Ford - 69.4 degrees mean annual temperature, 38-66 in the winter, 72-98 in the summer
8c
Caddo/LBJ - 35.4 in
Commons Ford - 28 in
8d
Caddo/LBJ - Little Bluestem, Big Bluestem, Yellow Indiangrass, and Switchgrass (The big four prairie grasses)
Commons Ford - The big four, plus Sideoats Grama, Texas Grama, and Hairy Grama
8e
Caddo/LBJ - Recreation, Hunting, Grazing, Hiking, Camping
Commons Ford - Recreation, Bird Watching, Educational Outreach, Scientific Research
9
Grasslands are important storehouses of biodiversity, clean and store water, clean air, sequester carbon, and serve as food for humans and animals, including key pollinators. Restoring and protecting grasslands can help provide clean water and air, secure soil from erosion, and ensure survival of pollinators and migratory birds.
Grasslands can be set aside as preserves, restored to native species, and managed through controlled burns and controlled access. You can take steps to protect and preserve smaller plots of grasslands by changing some areas in your yard or neighborhood to native grasses and wildflowers, reducing the use of yard chemicals, and learning more about and sharing with others the importance of grasslands.
10
10a
A one-meter study could be a Sabbath Afternoon activity, or perhaps on a club campout, check the same spot at different times during the day, to see the changes in what insects, spiders, and animals visit the spot. For inspiration, check out Chris Helzer’s Square Meter Photography Project
10b
Remember that the honor focuses on temperate grasslands, not the tropical grassland/savannah of Africa. However, you may want to use your zoo visit to study the animals of both temperate and tropical grasslands, and compare their similarities and differences to see how the different ecosystems highlight similar or alternative adaptations by animals.
10c
Live Feeds are a mixed bag, because animals are not necessarily predictable in when and where they may be, but a few that are relatively popular include:
Canada’s Grasslands National Park has two live webcams available: Bison Watering Hole Bison Calving Plains
The Forest Service, in partnership with the Nature Conservancy and the National Forest Foundation has a live cam set up at Midewin National Tallgrass Prairie to watch an introduced bison herd.
Devil’s Tower National Monument has a camera set up at the prairie dog town, though it only updates a still image every 30 seconds.
The Nature Conservancy’s Dunn Ranch Prairie also has a webcam, and archived video of their live cam feed.
10d
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