BS102 Environmental Biology

1. BS102 Environmental Biology Lecture Notes Packet #3 Daniel W. Ward BS102 Environmental Biology

2. Land Biomes • Connections between Climate and Vegetation • Climate • the average long term (30 years) weather of an area. • it determines the type of vegetation of that area. • factors which determine climate: • temperature • precipitation • Biome • a region of the world with a characteristic type of natural, undisturbed plant community. BS102 Environmental Biology

3. Land Biomes • Three Major Types of Land Biomes • Deserts / Semideserts • Grasslands • Forests BS102 Environmental Biology

4. Land Biomes • Deserts / Semideserts • General Characteristics • plants exhibit a slow rate of growth. • there is low species diversity. • there are periodic water shortages. • they take a long time to recover from any type of disruption. BS102 Environmental Biology

5. Land Biomes • Tropical Deserts • compose 1/5 of the world’s desert areas. • they are one of the most dry areas on the planet. • few plants can survive there. • characterized by hard, windblown surfaces strewn with rocks and some sand. • examples are the Sahara and Namib deserts. BS102 Environmental Biology

6. Land Biomes • Temperate Deserts • exhibit some seasonal temperature differences. • during the summer, the daytime temperatures are hot. • during the winter, the daytime temperatures are cool. • an example would be the Mojave desert. • Cold Desert • exhibit definite seasonal temperature differences. • summers are hot. • winters are cold. • an example would be the Gobi desert. BS102 Environmental Biology

7. Land Biomes • Semideserts • have a long dry season followed by a short, heavy rainy season. • dominated by thorn trees and shrubs. • located between true deserts and grasslands. BS102 Environmental Biology

8. Land Biomes • Grasslands • Tropical Grasslands • exhibit high average temperatures. • have low to moderate average precipitation. • they are located in a wide belt on each side of the equator beyond tropical rain forests. • they contain huge herds of grazing and browsing hoofed animals. • they often have fires in the dry season. • an example would be the savannas of Africa. BS102 Environmental Biology

9. Land Biomes • Temperate Grasslands • cover vast areas of the interiors of the major continents. • exhibit bitterly cold winters and hot, dry summers. • suffer from occasional fires. • experience frequent droughts. • Types: • Tall Grass Prairie - Midwest, western US and Canada. • Short Grass Prairie - Midwest, western US and Canada. • Pampas - South America. • Veld - Africa. • Steppe - central Europe and Asia. BS102 Environmental Biology

10. Land Biomes • Polar Grasslands / Arctic Tundra • bitterly cold and windy most of the year. • covered with snow and ice much of the year. • experience long, dark winter and short, long daylight summers. • covered with a thick, spongy mat of low growing plants. • located south of the polar ice cap (northern hemisphere). • low decomposition rate, shallow soil, slow growth rates make it very easy to disrupt. BS102 Environmental Biology

11. Land Biomes • Permafrost • thick layer of ice beneath the soil’s surface that remains frozen all year round. • prevents the establishment of trees. • the upper layer thaws during the summer but the moisture can’t seep into the ground. BS102 Environmental Biology

12. Land Biomes • Tropical Rain Forest • this is a type of evergreen broadleaf forest. • it is located near the equator. • it covers only 2% of the Earth’s surface. • characterized by warm annual mean temperatures, with little seasonal or daily variation. • also is characterized by high humidity and almost daily heavy rainfall. • contains the greatest number of species per unit of area of any biome. • soil nutrients are a limiting factor, not water and temperature. BS102 Environmental Biology

13. Land Biomes • Tropical Deciduous Forest • located between tropical rain forests and tropical savannas. • characterized by being warm all year round. • experiences alternating wet (monsoon) and dry seasons. • composed of a mixture of drought resistant tropical evergreens and deciduous trees (loose their leaves during the dry season). • Tropical Scrub Forest • similar to tropical deciduous forest, except it occurs where the dry season is longer. • mainly composed of small deciduous trees and shrubs. BS102 Environmental Biology

14. Land Biomes • Temperate Deciduous Forest • experiences moderate average temperatures. • characterized by 4 distinct seasons with long summers and mild short winters. • precipitation is abundant and spread over the entire year. • plants life is dominated by a few species which survive the winters by dropping their leaves and becoming dormant. BS102 Environmental Biology

15. Land Biomes • Evergreen Coniferous / Boreal Forest / Taiga • located just south of the arctic tundra. • experience a sub-arctic climate… • long, cold, dry winters with 6-8 hours of light per day. • short, mild summers with 19 hours of light. • dominated by a few species of conifers (fairly low plant diversity). • fallen “needles” cover the nutrient poor forest floor making the soil acidic and preventing the growth of most other plants. • during the summer the forest floor retains water and forms bogs. BS102 Environmental Biology

16. Water Environments • water covers over 70% of the Earth’s surface. • it plays a major role in regulating the Earth’s climate. • Types of Water Environments: • Ocean / Marine • Freshwater Lakes • Freshwater Streams • Inland Wetlands BS102 Environmental Biology

17. Water Environments • Ocean Zones • Coastal Zone • usually warm water rich in nutrients. • includes the shallow water extending from the high tide mark on the land to the edge of the continental shelf. • composes less then 10% of all oceans areas. • contains 90% of all marine species and it is the site of the major commercial fisheries. • has a high primary productivity per unit area. • most densely populated and intensely used of the ocean zones. BS102 Environmental Biology

18. Water Environments • Examples: • Coral Reefs • located in tropical and subtropical oceans. • composed of coral, algae, and other producers. • they provide habitats for many marine species. • protect 15% of all coastlines from erosion. • they grow very slowly and can be disrupted easily. • Estuaries • where fresh water and salt water mix (usually near the mouths of rivers). BS102 Environmental Biology

19. Water Environments • Coastal Wetlands • land which is covered all or part of the the year with salt water. • these areas provide breeding areas and habitat for a variety of wildlife. • these are being lost rapidly. • Beaches • Rocky Shores - rocks and tidal pools • Barrier Beaches - gentle slope to the ocean, sand dunes, they are prime development sites. • Barrier Islands • parallel running, long, thin, offshore islands. • protect mainland, estuaries, lagoons, and wetlands. BS102 Environmental Biology

20. Water Environments • Open Ocean • contains 10% of all marine species. • characterized by low primary productivity per unit area. • Subdivided based on light penetration. • Vertical Zones: • Eupohtic Zone • photosynthetic zone, high light penetration. • Bathyl Zone • twilight zone, moderate light penetration. • Abyssal Zone • darkness zone, little or no light penetration. BS102 Environmental Biology

21. Water Environments • Freshwater Lakes • large natural bodies of standing fresh water. • formed when rainfall, runoff, flowing groundwater fills depressions in the Earth. • these depressions are formed by… • placation. • crystal displacement. • volcanic activity. BS102 Environmental Biology

22. Water Environments • Types of Freshwater Lakes (based on nutrients) • Eutrophic Lake • have a large supply of nutrients. • Oligotrophic Lake • small supply of nutrients. • Mesotrophic Lake • moderate supply of nutrients. BS102 Environmental Biology

23. Water Environments • Lake Zones • Littoral Zone • the edge of the lake. • most submerged vegetation occurs here. • Limnetic Zone • upper zone of the lake. • considerable light penetration. • Profundal Zone • the lower zone of the lake. • moderate light penetration. • Benthic Zone • the bottom of the lake (mud). BS102 Environmental Biology

24. Water Environments • Thermal Stratification (deep lakes) • thermal stratification occurs due to the fact that water is densest as a liquid (4 degrees centigrade) rather than a solid (0 degrees centigrade). • Epilimnion • the upper layer of warm water and high levels of dissolved oxygen. • Hypolimnion • the lower layer of cold, denser water with low levels of dissolved oxygen. BS102 Environmental Biology

25. Water Environments • Thermocline • the middle layer where temperature change rapidly with depth increases. • acts as a barrier to the transfer of nutrients and dissolved oxygen between the upper and lower layers. BS102 Environmental Biology

26. Water Environments • Turnover • Fall Turnover • result of the cooling atmosphere. • the epilimnion sinks to the bottom when it cools to around 4o C. • the thermocline disappears. • this brings nutrients from the bottom sediments to the top. • also brings dissolved O2 from the top to the bottom. • Spring Turnover • due to the warming atmosphere. • warms the epilimnion to 4o C, and it sinks to the bottom. • the result is the same as fall turnover. BS102 Environmental Biology

27. Water Environments • Freshwater Streams • flowing bodies of surface water. • Watershed / Drainage Basin • the land area that delivers water, sediment, and dissolved substances by small streams, to large streams, and eventually to the ocean. BS102 Environmental Biology

28. Water Environments • River System Zones • Headwater / Source Zone • composed of cold, clear water. • turbulent flow results in large amounts of O2 being dissolved from the air. • Transition Zone • the merging of headwater streams to form wider, deeper streams. • flow is down gentle slopes with fewer obstacles. BS102 Environmental Biology

29. Water Environments • Flood Plain Zone • transition zone streams merge to form wide, deep rivers. • meander across broad, flat valleys. • main channels support a variety of species. • backwaters have species similar to lakes. BS102 Environmental Biology

30. Water Environments • Inland Wetlands • covered by freshwater at least part of the year. • located away from coastal areas. • includes… • bogs, marshes, prairie potholes, swamps, mud flats, flood plains, wet meadows. wet tundra. • provide habitats for wildlife. • improve the water quality by filtering, diluting, and degrading sediments and pollutants as water flows through them. BS102 Environmental Biology

31. Water Environments • regulate stream flow by storing water during periods of heavy rainfall - releases it slowly thus reducing erosion and damage. • recharges the groundwater supplies. BS102 Environmental Biology