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BS102 Environmental Biology1 Lecture Notes Packet #3 Daniel W. Ward
BS102 Environmental Biology2 Land Biomes u Connections between Climate and Vegetation u Climate u the average long term (30 years) weather of an area. u it determines the type of vegetation of that area. u factors which determine climate: u temperature u precipitation u Biome u a region of the world with a characteristic type of natural, undisturbed plant community.
BS102 Environmental Biology3 Land Biomes u Three Major Types of Land Biomes u Deserts / Semideserts u Grasslands u Forests
BS102 Environmental Biology4 Land Biomes u Deserts / Semideserts u General Characteristics u plants exhibit a slow rate of growth. u there is low species diversity. u there are periodic water shortages. u they take a long time to recover from any type of disruption.
BS102 Environmental Biology5 Land Biomes u Tropical Deserts u compose 1/5 of the world’s desert areas. u they are one of the most dry areas on the planet. u few plants can survive there. u characterized by hard, windblown surfaces strewn with rocks and some sand. u examples are the Sahara and Namib deserts.
BS102 Environmental Biology6 Land Biomes u Temperate Deserts u exhibit some seasonal temperature differences. u during the summer, the daytime temperatures are hot. u during the winter, the daytime temperatures are cool. u an example would be the Mojave desert. u Cold Desert u exhibit definite seasonal temperature differences. u summers are hot. u winters are cold. u an example would be the Gobi desert.
BS102 Environmental Biology7 Land Biomes u Semideserts u have a long dry season followed by a short, heavy rainy season. u dominated by thorn trees and shrubs. u located between true deserts and grasslands.
BS102 Environmental Biology8 Land Biomes u Grasslands u Tropical Grasslands u exhibit high average temperatures. u have low to moderate average precipitation. u they are located in a wide belt on each side of the equator beyond tropical rain forests. u they contain huge herds of grazing and browsing hoofed animals. u they often have fires in the dry season. u an example would be the savannas of Africa.
BS102 Environmental Biology9 Land Biomes u Temperate Grasslands u cover vast areas of the interiors of the major continents. u exhibit bitterly cold winters and hot, dry summers. u suffer from occasional fires. u experience frequent droughts. u Types: u Tall Grass Prairie - Midwest, western US and Canada. u Short Grass Prairie - Midwest, western US and Canada. u Pampas - South America. u Veld - Africa. u Steppe - central Europe and Asia.
BS102 Environmental Biology10 Land Biomes u Polar Grasslands / Arctic Tundra u bitterly cold and windy most of the year. u covered with snow and ice much of the year. u experience long, dark winter and short, long daylight summers. u covered with a thick, spongy mat of low growing plants. u located south of the polar ice cap (northern hemisphere). u low decomposition rate, shallow soil, slow growth rates make it very easy to disrupt.
BS102 Environmental Biology11 Land Biomes u Permafrost u thick layer of ice beneath the soil’s surface that remains frozen all year round. u prevents the establishment of trees. u the upper layer thaws during the summer but the moisture can’t seep into the ground.
BS102 Environmental Biology12 Land Biomes u Tropical Rain Forest u this is a type of evergreen broadleaf forest. u it is located near the equator. u it covers only 2% of the Earth’s surface. u characterized by warm annual mean temperatures, with little seasonal or daily variation. u also is characterized by high humidity and almost daily heavy rainfall. u contains the greatest number of species per unit of area of any biome. u soil nutrients are a limiting factor, not water and temperature.
BS102 Environmental Biology13 Land Biomes u Tropical Deciduous Forest u located between tropical rain forests and tropical savannas. u characterized by being warm all year round. u experiences alternating wet (monsoon) and dry seasons. u composed of a mixture of drought resistant tropical evergreens and deciduous trees (loose their leaves during the dry season). u Tropical Scrub Forest u similar to tropical deciduous forest, except it occurs where the dry season is longer. u mainly composed of small deciduous trees and shrubs.
BS102 Environmental Biology14 Land Biomes u Temperate Deciduous Forest u experiences moderate average temperatures. u characterized by 4 distinct seasons with long summers and mild short winters. u precipitation is abundant and spread over the entire year. u plants life is dominated by a few species which survive the winters by dropping their leaves and becoming dormant.
BS102 Environmental Biology15 Land Biomes u Evergreen Coniferous / Boreal Forest / Taiga u located just south of the arctic tundra. u experience a sub-arctic climate… u long, cold, dry winters with 6-8 hours of light per day. u short, mild summers with 19 hours of light. u dominated by a few species of conifers (fairly low plant diversity). u fallen “needles” cover the nutrient poor forest floor making the soil acidic and preventing the growth of most other plants. u during the summer the forest floor retains water and forms bogs.
BS102 Environmental Biology16 Water Environments u water covers over 70% of the Earth’s surface. u it plays a major role in regulating the Earth’s climate. u Types of Water Environments: u Ocean / Marine u Freshwater Lakes u Freshwater Streams u Inland Wetlands
BS102 Environmental Biology17 Water Environments u Ocean Zones u Coastal Zone u usually warm water rich in nutrients. u includes the shallow water extending from the high tide mark on the land to the edge of the continental shelf. u composes less then 10% of all oceans areas. u contains 90% of all marine species and it is the site of the major commercial fisheries. u has a high primary productivity per unit area. u most densely populated and intensely used of the ocean zones.
BS102 Environmental Biology18 Water Environments u Examples: u Coral Reefs u located in tropical and subtropical oceans. u composed of coral, algae, and other producers. u they provide habitats for many marine species. u protect 15% of all coastlines from erosion. u they grow very slowly and can be disrupted easily. u Estuaries u where fresh water and salt water mix (usually near the mouths of rivers).
BS102 Environmental Biology19 Water Environments u Coastal Wetlands u land which is covered all or part of the the year with salt water. u these areas provide breeding areas and habitat for a variety of wildlife. u these are being lost rapidly. u Beaches u Rocky Shores - rocks and tidal pools u Barrier Beaches - gentle slope to the ocean, sand dunes, they are prime development sites. u Barrier Islands u parallel running, long, thin, offshore islands. u protect mainland, estuaries, lagoons, and wetlands.
BS102 Environmental Biology20 Water Environments u Open Ocean u contains 10% of all marine species. u characterized by low primary productivity per unit area. u Subdivided based on light penetration. u Vertical Zones: u Eupohtic Zone u photosynthetic zone, high light penetration. u Bathyl Zone u twilight zone, moderate light penetration. u Abyssal Zone u darkness zone, little or no light penetration.
BS102 Environmental Biology21 Water Environments u Freshwater Lakes u large natural bodies of standing fresh water. u formed when rainfall, runoff, flowing groundwater fills depressions in the Earth. u these depressions are formed by… u placation. u crystal displacement. u volcanic activity.
BS102 Environmental Biology22 Water Environments u Types of Freshwater Lakes (based on nutrients) u Eutrophic Lake u have a large supply of nutrients. u Oligotrophic Lake u small supply of nutrients. u Mesotrophic Lake u moderate supply of nutrients.
BS102 Environmental Biology23 Water Environments u Lake Zones u Littoral Zone u the edge of the lake. u most submerged vegetation occurs here. u Limnetic Zone u upper zone of the lake. u considerable light penetration. u Profundal Zone u the lower zone of the lake. u moderate light penetration. u Benthic Zone u the bottom of the lake (mud).
BS102 Environmental Biology24 Water Environments u Thermal Stratification (deep lakes) u thermal stratification occurs due to the fact that water is densest as a liquid (4 degrees centigrade) rather than a solid (0 degrees centigrade). u Epilimnion u the upper layer of warm water and high levels of dissolved oxygen. u Hypolimnion u the lower layer of cold, denser water with low levels of dissolved oxygen.
BS102 Environmental Biology25 Water Environments u Thermocline u the middle layer where temperature change rapidly with depth increases. u acts as a barrier to the transfer of nutrients and dissolved oxygen between the upper and lower layers.
BS102 Environmental Biology26 Water Environments u Turnover u Fall Turnover u result of the cooling atmosphere. u the epilimnion sinks to the bottom when it cools to around 4 o C. u the thermocline disappears. u this brings nutrients from the bottom sediments to the top. u also brings dissolved O 2 from the top to the bottom. u Spring Turnover u due to the warming atmosphere. u warms the epilimnion to 4 o C, and it sinks to the bottom. u the result is the same as fall turnover.
BS102 Environmental Biology27 Water Environments u Freshwater Streams u flowing bodies of surface water. u Watershed / Drainage Basin u the land area that delivers water, sediment, and dissolved substances by small streams, to large streams, and eventually to the ocean.
BS102 Environmental Biology28 Water Environments u River System Zones u Headwater / Source Zone u composed of cold, clear water. u turbulent flow results in large amounts of O 2 being dissolved from the air. u Transition Zone u the merging of headwater streams to form wider, deeper streams. u flow is down gentle slopes with fewer obstacles.
BS102 Environmental Biology29 Water Environments u Flood Plain Zone u transition zone streams merge to form wide, deep rivers. u meander across broad, flat valleys. u main channels support a variety of species. u backwaters have species similar to lakes.
BS102 Environmental Biology30 Water Environments u Inland Wetlands u covered by freshwater at least part of the year. u located away from coastal areas. u includes… u bogs, marshes, prairie potholes, swamps, mud flats, flood plains, wet meadows. wet tundra. u provide habitats for wildlife. u improve the water quality by filtering, diluting, and degrading sediments and pollutants as water flows through them.
BS102 Environmental Biology31 Water Environments u regulate stream flow by storing water during periods of heavy rainfall - releases it slowly thus reducing erosion and damage. u recharges the groundwater supplies.