BIO 373 1st Edition Lecture 4 Outline of Last Lecture I Regional Climates a Elevation and precipitation b Deforestation II Climate variation a Intertropical convergence zone b El Nino Souther Oscillation c La nina d Pacific Decadal Oscillation e Long term climate variation III The chemical environment a Salinity b Oxygen availability Outline of Current Lecture I Biosphere a Case Study American Serenget II Terrestrial Biomes a Tropical rainforest b Hot deserts c Temperate grassland d Temperate deciduous e Boreal forests f Tundra III Mountain biological zones Current Lecture Biosphere American Serenget o Large diversity of animals o Suddenly a huge extinction of animals Wooly mammoth sabor tooth etc These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute o Possible causes Over hunting by humans colonizing there The animals evolved without presence of humans so were not adapted when humans arrived Humans also may have carried diseases with them o Megafauna bison deer elk Terrestrial Biomes Characterized by forms of dominant vegetation o Because plant don t move they can tell us about the physical environment b observing their growth forms See slide for example o Deciduous wet cold o Suvvulents dry hot o Evergreen moist warm fertile soil o Grasses deep rooted can withstand fire Convergence evolution of similar growth forms among distantly related species in response to similar selection pressures o Example cactus and euphorb Cactus is American and euphorb is African Similar growth forms but completely unrelated Both live in dry environments and adapted similarly Average annual temperature and precipitation can predict biome distributions quite well Note that at very low temperatures and very high mean precipitation there are no associated biomes o A constrain of the physical environment Global Biome Distribution affected by human activities change the landscape o Resource extraction o Urban development o Agriculture Biomes will discuss some know the others for extra credit on exam o Tropical rainforest 10 degrees N and S from equator South America to Mexico Brazil Precipitation around 200 centimeters annually and temperature of 25 degrees Very consistent Evergreen broad leaf tall trees Competing for light lots of water and solar radiation Layers of vegetation o Canopy mid canopy understory shrubs and small trees o Canopy blocks light for understory These plants have adaptations for this o Hot Desert 30 degrees latitude Very low precipitation High temperature but with lots of fluctuation Less vegetation less retention of heat o Less evapotranspiration and less capture of solar radiation Succulents short shrubs grasses Humans use deserts for agriculture and animal grazing Pump water out of soil Causes soil salinity to increase o Temperate grassland Warm summer precipitation Cold winters very little precipitation Fires Most fertile grasslands provide most agriculture in the world Initially large diversity of grasses but this has decreased significantly due to human impact o Temperate deciduous forest Fluctuation in temperature but normally fairly warm Ranges from 20 degrees to freezing freezing is rare Deciduous broadleaf trees Drop leaves during winter o Before dropping leaves the plant captures the chlorophyll from leaves and stores in trunk o recycled to use when regenerating leaves but still costly in energy for plants because other nutrients are also required for regeneration Fertile soils and temperate climate makes it good for agriculture Very little old growth in temperate forests remains Northern hemisphere o Boreal Forests 50 60 degrees latitude Northern hemisphere We have more land mass more continental climates that can lead to this type of vegetation Cold temperatures but can reach 20 degrees Celsius Frozen temperatures are frequent Precipitation is low 50 mm at the most Evergreen needle like leaves Good for cold dry Permafrost soil surface freezes with trapped water Can kill trees Composition is low in this area Low human impact o Tundra Lots of wind low temperature Vegetation grows close to ground to maintain higher temperature and protect from wind Low human impact but increased recently due to exploration and climate change Mountain biological zones different elevation temperatures etc o Lower montane Grasslands o Montane Deciduous o Subalpine Boreal o Alpine tundra