Lecture 12 Wednesday, June 27, 2007 1. Temperate Rain ForestsHuge trees, moderate maritime climate, lots of precipitationa. Structurei. Tall, dense canopy of needle-& small broad-leaf evergreensii. Deciduous &/or evergreen sub-canopyiii. High biomass and productivityiv. Not much canopy diversity. Higher sub-canopy diversityb. Distributioni. West Coasts: Northern California to SE Alaskaii. Southern tip of New Zealandiii. Southern Chile (mixed evergreen needle-leaf and broadleaf evergreen trees)c. Climatei. “Marine West Coast”ii. Lots of precipitation, winter high. iii. Drier summersiv. Mild temps (oceanic influence):d. Disturbancei. Windfall1. Nursery logsii. Infrequent fire, only in extreme dry yearsiii. Infrequent landslide due iv. to extreme precipitationv. earthquakesvi. Volcano eruptionsvii. Humans: Logging, Clearing for developmentNon-Forested Biomes2. Mediterranean Shrublandsa. Structurei. Shrubsii. Dominant species: Chamise, Ceanothus, Mountain Mahogany, Oaksiii. “Sclerophyllous” Vegetation: hard leathery leavesiv. Leaves are evergreen or drought-deciduous and generally very smallb. Mediterranean Shrublands: StructureTwo different types in Californiai. Coastal Sage Scrub: 2-layered 1. Shrubs = 1 m tall spaced far apart2. Lots of grasses and forbs “understory”3. Located along the coast (low elevation)ii. Chaparral: a thick wall of shrubs1. 2 to 5 dominant shrub species2. Lacks much understory in mature stage3. Located at higher elevations than C.S.S.c. Distributioni. 5 disjunct locationslocated on west coasts of continents between 30-40 degrees latitude1. Southern California: Chaparral, C.S.S.2. South America (Chile): Matorral 3. Australia: Heath4. South Africa: Fynbos5. Mediterranean Sea: Maquis or Matorrald. Climatei. Winter high in precipitationii. Definite summer droughtiii. Temperatures mild in winter, mild to hot in summeriv. Similar patterns to Temperate Rain Foreste. Disturbancei. Landslides, Floodsii. Fire is very important! iii. Frequent firesiv. Re-sprouting shrubs (quick return interval)v. “Fire Followers” vi. Human disturbances: clearing for development, changing fire regime (suppression vs acceleration)3. DesertsCharacterized by very low precipitationa. Warm desertsi. Lower latitudes, warmer temperaturesii. Subtropical High Pressure Zonesiii. Moderately Complex Structureiv. Shrub layerv. Annual grasses and forbs (after rains)vi. “Tree” layer: Saguaro cacti, Joshua Treesvii. Moderate biodiversityviii. Low productivity, low biomass b. Cold desertsi. Cold Winters, Warm Summersii. Rainshadow Desertsiii. Low diversity, productivity, and biomassiv. Lacks a “tree” layerv. Few cactivi. Dominated by shrubs and grassesc. Case studies of North American Desertsi. Chihuahuan Desert1. Warm Desert2. Yuccas, Creosote Bush3. Summer high precipitation (Monsoon)4. Texas, New Mexico, Northern Mexicoii. Sonoran Desert1. Warm Desert2. Arizona, California, Northern Mexico3. Two precipitation highs4. High biodiversity5. Lots of large cactia. Saguarosb. Organ pipe cactusiii. Mojave Desert1. Warm/Cold Desert2. Southeastern California, Southern Nevada, Northwestern Arizona3. Creosote Bush4. Joshua Trees5. Winter high Precip.iv. Great Basin Desert1. Cold, rainshadow desert2. Winter high precip.3. Sagebrush, Rabbitbrush, Greasewood4. Eastern Oregon, Nevada, Utah, parts of Idaho and Wyomingv. Disturbances1. Wind and water erosion2. Flooding during rain events3. Not much fire historically4. Humana. Off road vehiclesb. Changes in fire regimec. Grazingd. Mininge. Exotic species: Cheat Grassi. Invasive exotic speciesii. Grows between shrubs iii. Highly flammableiv. Shrubs burn, don’t come backv. Cheat Grass thrives with firevi. Sagebrush shrubland à Cheat grassvii. A “positive feedback” 4. Temperate Grasslandsa. Tallgrass vs. Shortgrass: A precipitation gradientb. Tall Grass Prairiei. Grasses and Forbsii. Historically maintained by fire (2-4 year interval)iii. Without fire, may become a deciduous forestiv. Moderate to low biomass, but high productivityv. Best soils in the world (Mollisols)vi. Dominated by agriculturec. Short Grass Prairiei. Dominated by short grasses, forbs and shrubsii. Drier than Tall Grass Prairieiii. Less fire because less fueliv. Soils productive, not as rich as tall grassv. Biomass and productivity fairly lowvi. Grazing and agriculture (irrigation needed)5. Arctic and Alpine Tundraa. Propertiesi. Vegetation consists of grasses, sedges, forbs, and low shrubs (willows)ii. Biomass and productivity are lowiii. Biodiversity is low/moderateiv. Vegetation adapted to extreme coldb. Arctic vs. Alpine Tundrac. Arctic Tundrai. High latitudesii. Precipitation may be lowiii. Permafrost soilsiv. Surface soils are wetv. Extreme cold wintersvi. Large temperature rangesd. Alpine Tundrai. High altitudesii. Precipitation tends to be high (mountain snows)iii. Large temp rangeiv. Wind
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