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Nevada’s Bioregions Objectives • Define was a bioregion is and compare it to an ecosystem and a biome. • Identify and describe the unique bioregions of the state of Nevada. • Give examples of the characteristic plants and animals found in each Nevada bioregion. What is a Bioregion? • Bioregion: an area constituting a natural ecological community with characteristic flora, fauna, and environmental conditions and bounded by natural rather than artificial borders. – One bioregion is distinguishable from another by its plants, animals, water, climate, soils and land-forms. What is a Bioregion? • • What it is: – an area distinguished by its natural biotic and abiotic features. – boundaries are more closely related to the unique communities of plants and animals found there than they are to the overall climate. What it is not: – Not a biome. Several bioregions may exist within a simgle biome. • Area is much smaller than a biome – Not an ecosystem. Several ecosystems may exist within a single bioregion. • Area is larger than a single ecosystem. Nevada's Bioregions • Geography: – Basin and Range Province: A land of Extremes • Area is characterized by a series of Northeast trending mountain ranges with broad valleys in between. • Ranges force precipitation out of the prevailing Westerlies as air rises to move over the crest. • Microclimates on the ranges are typically wetter and cooler than the valleys. Nevada’s Bioregions Nevada’s Bioregions Average January Temperatures Average July Temperatures Basin and Range Province The Basin and Range province has extremes of altitude change in a short distance. Climate conditions vary with altitude and affect the plants and animals that are found there. Each 1000 ft of altitude gain causes a 3.5 degree F decrease in average temperature. Lowest altitudes tend to be the driest. Tallest peaks may have snow year-round (alpine tundra conditions). Mojave Desert Bioregion • Southern Nevada: – Mojave Desert Bioregion: – Hot, dry desert with high summer temperatures and warm mild winters. – Dominate plant species are adapted to survive extreme heat and drought conditions; • Joshua tree – Largest member of the yucca family • Mojave Yucca – AKA Spanish bayonet – Native people used fibers and seeds – Home to the yucca night lizard, a relative of geckos Mojave Desert Bioregion • Southern Nevada: • Creosote bush – Poisons soil in its root zone – Will drop it’s leaves to conserve water in extreme drought – Spreads by seeds and clones – Could be the oldest living organism on earth (unconfirmed) • Cholla – AKA Jumping Cholla, Teddy Bear Cholla – Several different species are present in this bioregion – Grows in large “forests” that can cover acres of land – Spreads by seeds and sprouting from broken pieces carried by animals, wind, or water Mojave Desert Bioregion • Southern Nevada: – Dominate animal species include: – Reptiles: • Collared Lizard – Large carnivorous lizard – Eats insects, small rodents, and other lizards • Chuckwalla – Largest lizard of this bioregion (18 to 24 inches) – Is a herbivore that eats fruit, flowers, and vegetation – Wedges itself in rock outcrops for protection • Desert iguana – Another vegetarian that eats flowers – Prefers sandy habitat because it lives in burrows Mojave Desert Bioregion • Southern Nevada: – Reptiles: • Sidewinder – AKA Horned Rattler – One of three members of the rattlesnake family in this bioregion – Adapted to movement over loose, sandy soil • Whiptail – Members of this species can change sex in a single-sex population • Zebra Tailed Lizard – One of the few reptiles active mid-day – Curls its tail up over its back when it runs to confuse predators – Could be Nevada's fastest lizard • Desert Tortoise – Nevada state reptile – Another herbivore that eats flowers – Can live 80 to 100 years Mojave Desert Bioregion • Southern Nevada: – Rodents: • Kangaroo Rat – Can survive without ever drinking water – Extracts water from the metabolism of carbohydrates in the seeds it eats • Pack Rat – Builds a midden of collected items which it may “pack” from place to place – Attracted to light colored, shiny objects – Climate change has brought about adaptations to be able to eat toxic Creosote Bush • Jack Rabbit – Not a rabbit, but a hare – Named by prospectors after the burrows they used as pack animals • Common Field Mouse – Most widely distributed rodent in North America Mojave Desert Bioregion Southern Nevada: – Birds: • Raven – Large intelligent bird that lives in cooperative groups – Will hunt or scavenge to survive • Cactus Wren – Common bird of Joshua forests – Eats seeds and insects • Burrowing Owl – Night flying carnivore that eats small rodents – Spends daylight hours in a burrow to escape the heat • Roadrunner – Hunts insects, snakes, and lizards – Often builds nests in the tops of cholla or other cactus Mojave Desert Bioregion • Southern Nevada: – Larger mammals: • Coyote – Prefers meat but will eat just about anything – Escapes the heat in an underground den • Bobcat – Hunts rabbits, mice, and pack rats • Kit Fox – Competes with coyote and bobcat for food – Smaller size gives it an advantage • Desert Bighorn Sheep – Nevada state mammal – Sure footed climber – Requires stable water sources End Section I