610 likes | 617 Views
California's deserts are characterized by low precipitation, extreme temperatures, and nutrient-poor soils. Learn about the unique features of the Great Basin, Mojave, and Colorado Deserts, including their diverse plant communities and elevation variations.
E N D
Deserts • Defined as a region that receives less than 10” of ppt a year • Irregular • Temperature extremes • Windy • Nutrient poor alkali soils • Low rates of primary productivity • High rates of evapotranspiration
Temperature Extremes • Dry desert air holds little moisture • Water moderates temperature • 50 F temp change between night & day
Convective uplift Heated Air Rises
Katabatic Airflow WINDY!!
Nutrient Poor Soils • Low rates of decomposition • Low primary productivity • Aeolian soils • Alkali
What Causes Deserts • Global climate patterns • Distance from ocean • Cooling and re-warming of air • Rainshadow effect
Deserts found at horse latitudes 30 Deg North & South
Cold water cools warm air Cold air forms precipitation
Air on leeward side warms as it drops • 1 deg per 100 M (5.5 def F per 1000 ft) • Warms 2X faster than cools
California’s Deserts • Latitude & local topography induces change • Great Basin Desert • Mojave Desert • Colorado Desert
Great Basin Desert • Northernmost distribution • East of Cascade range • Modoc Plateau • Western most distribution of basin & range province • Inyo-White mtns • Panamint Range • High elevation desert • 4000-5000 ft • Lava flows
Great Basin Desert • Higher Elevations • Most above 4,000 ft • Coolest desert • Precipitation mostly as winter snow • Spring growth • Interior basins with no drainage • Predominant plant community- Great Basin Sagebush scrub
Great Basin Sagebrush Scrub Biomass exceeds Coast Redwoods
Artemesia tridentata Miles Bio 13 2007
Mojave Desert • Rainshadow of Sierra Nevada & Coastal ranges • Average elevation 3500 ft
Mojave Desert • Warmer desert • Freezing winter, some snow at higher elevations • Transitional desert • Higher elevation Joshua forest • Lower elevation regions dominated by creosote bush
Colorado (Sonoran) Desert • Subdivision of Sonoran desert • Low elevation desert • Subtropical desert • Wet winters, monsoonal summers • Most biologically diverse
Colorado Desert • Warmest desert • Large cacti & legume trees • Suaro cactus & mesquite trees
Desert Woodlands • Found between montane forests & lower desert scrub communities • Dominated by mixture of desert shrubs & small xerophytic trees • 3% of California • Located between 2,500- 8,000 ft
Pinyon Juniper Woodland • 4,000-8,000 ft • Predominantly transmontane distribution with cismontane distribution in Southern California • Density varied according to local climate • Juniper more xerophytic than Pinyon pine • Juniper dominates in drier lower elevations • Pinyon dominates in moister higher elevations
Pinyon Jay • Cache pinyon seeds • Specialized esophagus • Social & gregarious • 500+ • Mated pair share caches
Joshua Tree Woodland • Higher elevations of Mojave desert & Eastern Sierra Nevada • Precipitation mostly as snow • Cold winter temperatures • Coarse, non-alkali soils