Grassland Biome Overview

Grassland Biome Overview

• Precipitation levels are insufficient for forests but too high for deserts.
• Grasses are the dominant producers, with several genera and species present, often with one or two dominant types.
• Most grasses have rhizomes and are wind-pollinated.
• Temperatures range from -20°F to 110°F, with colder extremes in the north.
• Annual precipitation varies from 6 to 40 inches (15 to 100 cm).
• Summer precipitation includes scattered rain and thunderstorms ("convection storms"); winter precipitation is more general (rain and snow).
• Soils are generally fertile, deep, and rich, with variability.
• Growing seasons last from 120 to 200 days.
• Topography is generally flat to rolling, with stream drainages and riverbanks.
• Fire plays a critical role in maintaining grasslands.
• Grazing animals (deer, antelope, buffalo), burrowing small animals (prairie dogs), and songbirds are dominant.

Grassland Types

• Grasslands cover much of the central United States.
• Tallgrass prairies (eastern US) are near Eastern Deciduous Forests and have tall grasses (3-4 ft or 1-1.5 m high) with deep roots. Annual precipitation is 24-40 inches (65-100 cm).
• Midgrass prairies (central US) have grasses 2-4 ft (1.5 m) tall and annual precipitation of 14-25 inches (35-65 cm).
• Shortgrass prairies (western US) cover the greatest area and are near western deserts. Grasses are short (less than 20 inches or 50 cm). Annual precipitation is approximately 10 inches.

Grassland Food Web & Adaptations

• Grassland food pyramid diagram provided as graphic.
• Plants: Many possess rhizomes (underground stems). Wind pollination is common. Fertile, deep soils are rich in nutrients. Native plants are perennials; crops are annuals. Grasses have a three-layer structure (roots, ground-level growth, taller foliage). Grazed foliage regenerates. Taller foliage withstands strong winds, fires, and temperature extremes. Herbs and legumes (nitrogen fixing) are among the grasses. Half of their growth is below ground level.
• Animals: Herding provides safety. Burrowers live in colonies. Birds are strong fliers; flight songs attract mates. Grazing animals have forward-facing eyes, are often built for speed, and frequently live in herds or colonies. Small animals hop, stand on haunches. Camouflage is prevalent. Underground burrows are common.

Examples of Grassland Species

• Allium canadense (Wild Onion): Perennial plant native to North America. Edible bulb with strong onion odor. Used historically as repellent for moths, insects, and even scorpions/lizards. Leaves are grass-like, near the base of a stem topped with star-shaped flowers. Flowering from May to June. Several look-alikes exist, therefore, careful identification is important.
• Andropogon gerardii (Big Bluestem): Tall grass native to North American prairies. Tolerant of moisture and soils, grows 1-3 m high. The stem base turns blue-purple as it matures. Deep roots and rhizomes (important for prairie soil stability). Good forage for livestock and potentially useful for ethanol production. Seed heads have three spike-like projections ("turkey foot" ). Often the late-successional grass, forming dense stands that shade out other species.
• Anemone canadensis (Crowfoot): Spring-flowering plant native to eastern North America. Grows 20-80 cm tall, prefers moist soils. Used traditionally by indigenous peoples for wound treatment. Has 5 sepals, obovate shape. Leaves have 3 segments (lanceolate or oblanceolate), with a variety of leaf shapes observed. Flowers are white or pink. Fruits in spheric/ovoid heads, with achenes (seeds) attached. Prefers moist areas. Spread through running rhizomes.
• Apocynum cannabinum (Dogbane): Poisonous perennial growing up to 2 meters tall. Avoid ingestion; all parts are toxic. Historically used as a fiber source, and in traditional medicine (now not recommended). Opposite, simple, broad lanceolate leaves. Reddish stems. Milky latex. Flowers in mid-summer. Can reduce crop yields when growing among them.
• Asclepias incarnata (Swamp Milkweed): Highly attractive to butterflies (hosts Monarch caterpillars). Prefers wet areas, grows 100-150 cm tall, has scented white roots and produces long seed pods with silky hairs for wind dispersal. Prefers moisture-retentive to damp soils, in full sun to partial shade. Prefers ponds, lakes, etc. Produces nectar for butterflies, and other pollinators. Variety in flower color exists; can vary from darker shades of pinkish-purple to soft, pinkish-purple and a white flowering form.
• Asclepias syriaca (Milkweed): Native to most of North America, often grown in gardens due to its attractiveness to butterflies. Produces copious seeds easily dispersed by wind (silky hairs). Stem and all parts produce white latex when broken. Opposite leaves (simple, broad ovate-lanceolate). Spherical umbels of small, fragrant flowers. Seeds attached to long, white flossy hairs. Prefers sandy soils and lots of sunlight.
• Calamagrostis canadensis (Bluejoint): Perennial grass in northern North America, tolerates wet areas, used for grazing, and can help prevent soil erosion. 60 centimeters to 1.5 meters tall; flat, drooping leaves with tiny hairs; inflorescence is up to 25 centimeters long and spikelets are purplish in color. Can be a nuisance plant on forest revegetation sites.
• Caltha palustris (Marsh Marigold): Early spring to late summer flowering, grows in wet bogs and marshes. Flowers are yellow and attract insects. Rounded to kidney-shaped, 3-20 cm leaves. Possesses a bluntly serrated margin and a thick, waxy texture. Early April/May flowering, valued for nectar/pollen for insects.
• Cynomys gunnisoni (Gunnison's Prairie Dog): Rodent species found in the four corners region of North America. Stout body, short tail (1.25 to 2.25 inches / 3 to 6 centimeters), body length of around 12 to 14 inches (30 to 37 centimeters), and average weight of 1.5 to 2.5 lbs (0.5 to 1 kg). Important part of the local food web. 22 teeth, 5 pairs of mammary glands.

Explore the fascinating characteristics of grassland biomes, where grasses thrive under specific precipitation conditions. Learn about the temperature ranges, soil fertility, and the role of fire in maintaining these ecosystems. This quiz also delves into various grassland types and the wildlife that inhabit them.