310 likes | 326 Views
Explore the six major biomes, from tropical rainforests to tundra regions, and learn about their unique characteristics and vegetation. Discover key ecosystems like deserts and temperate forests, each defined by distinct environmental factors and physiognomy. Gain insights into the diversity of plant life, with a focus on specific regions and their adaptations to varying climates.
E N D
Biomes Major ecosystems found in large geographic regions characterized by a distinct vegetative community --primarily a result of abiotic processes Physiognomy The overall appearance of a biome or community based on the relative density, height, and shape of its dominant vegetation
Six major biomes: 1. tropics: 0-10º 2. grasslands/savannah: 10-40º 3. deserts: 30º 4. temperate forests: 30-45º 5. coniferous forests or taiga: 60º 6. tundra: 60-90º
Tropical Biomes: • Most occur within 10° latitude of the of the equator • Defined by rainfall > 240 cm per year • Temperature and moisture not limiting factors, nutrients and light are
Amazon (Neotropics) SE Asia Congo Old World New World
Physiognomy of Tropics • high diversity of trees • 400-700 trees per hectare (2.47 acres) • 100-200 species represented • low population densities for each • dense canopy, stratified up to four levels
High light attenuation Humidity ~70% Temperature warmer cooler 90-95% Fig. 29.27 (EFB)
Leaf litter accumulates rapidly, but also decays rapidly Plants in competition for nutrients released by decay
Nurse tree with successional stages of growth to obtain nutrients released from decaying wood
Deserts are defined by rainfall: • true desert has < 12 cm/yr • extreme desert < 7 cm/yr • semi-desert has up to 40 cm/yr • evaporation exceeds rainfall
Deserts also characterized by: • hot days, cool nights from high albedo • sparse plant life • C4 and CAM photosynthesis • xerophytes • more living plant biomass below ground than above, sometimes 1:10 difference
Sonoran Desert Lowest, hottest desert up to 120° F in summer Bi-annual rainfall ~18 cm/yr Most diverse desert in NA Saguaro Cactus limited by temperature
Sonoran Desert, AZ cholla cactus ocotilla palo verde trees
Four major North American Deserts Mohave Sonoran
Most precipitation in winter 5-12 cm/yr Higher elevation than Sonoran Plants adapted to cooler temperatures Mohave Desert
Four major North American Deserts Mohave Sonoran Chihuahuan
Most precipitation in summer 15-20 cm/yr Dominated by low shrubs and cactus Chihuahuan desert and creosote
Four major North American Deserts Great Basin Mohave Sonoran Chihuahuan
Largest U.S. desert, considered a cold desert Elevations range from 5000-6000 feet Caused by a series of rainshadow effects Precipitation 15-25 cm/yr Dominated by sagebrush Great Basin Desert