BI 105A Environmental Biology

1. BI 105AEnvironmental Biology Professor Jill Nissen Montgomery College Fall 2006

2. Chapter 5 Ecosystems and The Physical Environment

3. Energy and Matter Living things depend on the abiotic environment to supply energy and essential materials Other aspects of the environment that affect organisms: • Solar radiation • Atmosphere • Ocean • Weather and climate • Internal planetary processes

4. Biogeochemical Cycles natural processes that involve the flow of matter from the nonliving environment (air, water, soil, rock) to living organisms, & back again Five representative types: • Carbon • Nitrogen • Phosphorus • Sulfur • Hydrologic

5. The Carbon Cycle Carbon is removed from the abiotic environment by: • photosynthesis Carbon is returned to the abiotic environment by: • cellular respiration • combustion • erosion

6. The Nitrogen Cycle Nitrogen cycles between the abiotic and biotic environment by a 5 step process: • Nitrogen fixation • Nitrification • Assimilation • Ammonification • Denitrification Mini-glossary page 107

7. The Phosphorous Cycle Recycling of phosphorous is slow because there is no gaseous form of phosphate that is biologically important • P erodes from rock and is absorbed from the soil by the roots of plants • P travels through the trophic levels and is released to the environment by the decomposers • Some P is deposited on the ocean floor and is out of the cycle for millions of years

8. The Sulfur Cycle Human activities have greatly increased sulfur emissions, which contribute to air pollution and acid deposition • Bacteria drive the sulfur cycle • Most sulfur occurs in rock or dissolved in the ocean • Atmospheric sulfur is minor and short-lived

9. The Hydrologic Cycle Water cycles from the ocean to the atmosphere to the land and back to the ocean main processes: • precipitation • evaporation • transpiration • condensation • percolation • runoff

10. Solar Radiation Most of the sun’s energy never reaches Earth. Of the energy that does reach earth: • 31% is reflected • 69% is absorbed and runs the hydrologic cycle, drives wind and ocean currents, and warms the planet, and drives photosynthesis • Less than 0.2% is captured by photosynthesis • Ultimately all the sun’s energy is lost as heat radiated back to space

11. Temperature Changes with Latitude Solar heating is uneven due to earth’s shape & tilt • Tropics are warmer than polar regions

12. Temperature Changes with Seasons Seasons are primarily caused by earth’s tilt • Axis tilted by 23.5 degrees

13. Global Air & Water Flow Circulation of the atmosphere and oceans is primarily caused by: • Differences in temperature • Coriolis Effect – the tendency of moving air or water to be deflected from its path, to the right in the N. Hemisphere and to the left in the S. Hemisphere

14. Surface Ocean Currents & Gyres

15. El Niño and La Niña El Niño is a periodic warming of the surface waters of the tropical east Pacific • every 3-7 years • currents slow or stop • fisheries’ production declines • unusual or disastrous weather can occur La Niña is a periodic cooling of the surface waters of the tropical east Pacific • also affects weather patterns

16. Weather vs. Climate Weather: The conditions in the atmosphere at a given place and time (short term) Climate: The average weather conditions that occur in a place over a period of years (long term)

17. Plate Tectonics The movement of the crustal plates that float on earth’s mantle Plate boundaries are sites of intense geological activity: • Mountain building • Earthquakes • Volcanoes

18. Plates and Boundary Locations Note the boundary types: Divergent, Convergent, Transform Environment, Fourth Edition/fig6.22

19. Plate Boundaries • Divergent boundary – area where new sea floor is created • Convergent boundary – subduction or mountain building • Transform boundary – fault lines, valleys, earthquakes Environment, Fifth Edition/fig5.23

20. Review Objectives • The Cycling of Materials within Ecosystems• Describe the main steps in each of these biogeochemical cycles: carbon, nitrogen, phosphorus, sulfur, and hydrologic cycles.• Describe how humans have influenced the carbon, nitrogen, phosphorus, sulfur, and hydrologic cycles. • Solar Radiation• Summarize the effects of solar energy on Earth’s temperature. • The Atmosphere• Discuss the roles of solar energy and the Coriolis effect in producing atmospheric circulation.• Define prevailing winds and distinguish among polar easterlies, westerlies, and trade winds. • The Global Ocean• Discuss the roles of solar energy and the Coriolis effect in producing global water flow patterns, including gyres.• Define El Niño–Southern Oscillation (ENSO ) and La Niña and describe some of their effects. • Weather and Climate • Distinguish between weather and climate. • Internal Planetary Processes• Define plate tectonics and explain its relationship to earthquakes and volcanic eruptions.