BIO 373 1st Edition Lecture 4 Outline of Last Lecture I. Regional Climatesa. Elevation and precipitationb. DeforestationII. Climate variationa. Intertropical convergence zoneb. El Nino Souther Oscillationc. La ninad. Pacific Decadal Oscillatione. Long term climate variationIII. The chemical environmenta. Salinityb. Oxygen availability Outline of Current Lecture I. Biospherea. Case Study—American SerengetII. Terrestrial Biomesa. Tropical rainforestb. Hot desertsc. Temperate grasslandd. Temperate deciduouse. Boreal forestsf. TundraIII. Mountain biological zonesCurrent LectureBiosphere- American Serengeto Large diversity of animalso 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 themo Megafauna= bison, deer, elkTerrestrial Biomes- Characterized by forms of dominant vegetationo Because plant don’t move, they can tell us about the physical environment b observing their growth forms- See slide for exampleo Deciduous- wet, coldo Suvvulents- dry, hoto Evergreen- moist, warm, fertile soilo Grasses- deep rooted, can withstand fire- Convergence= evolution of similar growth forms among distantly related species in response to similar selection pressureso 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 biomeso A constrain of the physical environment- Global Biome Distribution affected by human activities—change the landscapeo Resource extractiono Urban developmento 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 vegetationo Canopy, mid canopy, understory (shrubs and small trees)o Canopy blocks light for understory These plants have adaptations for thiso Hot Desert 30 degrees latitude Very low precipitation High temperature but with lots of fluctuation- Less vegetation, less retention of heato 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 increaseo 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 impacto 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 wintero Before dropping leaves the plant captures the chlorophyll from leaves and stores in trunko “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 hemisphereo 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 impacto 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 Grasslandso Montane Deciduouso Subalpine Borealo Alpine