Terrestrial Biodiversity

1. Terrestrial Biodiversity AP Environmental Science

2. Climate and Life on Land • Different climates lead to different communities of organisms, especially vegetation. • Biomes – large terrestrial (land) regions characterized by similar climate, soil, plants, and animals. • Each biome contains many ecosystems whose communities have adapted to differences in climate, soil, and other environmental factors.

3. Introduction to Climate

4. Weather or Climate? • Weather: physical conditions of the lower atmosphere that occur over hours or days. • Temperature • Precipitation • Humidity • Cloud coverage • Etc. • Climate: long term differences in temperature and precipitation • 3 decades (30 years) to 1000s of years • This distinction is important when discussing climate change/global warming. Long term data should be used. Climate matters because it determines where humans and other species can survive.

5. Different Climates on Earth • Tropical – areas near the equator, receives the most intense sunlight • Polar – areas near the poles, receives the least intense sunlight • Temperate - between tropical and poles • Climate varies in different parts of Earth because of an uneven distribution of heat and precipitation around the world by air and ocean currents.

6. Factors That Determine How Air Circulates • Uneven heating of the Earth’s surface by the sun • Air is heated more at the equator where the sun strikes directly, strikes the poles at an angle and covers a larger area. • Tropical = hot • Polar = cold • Temperate = hot and cold seasons • More solar radiation = more evaporation = more condensation = more precipitation

7. Factors That Determine How Air Circulates • Rotation of Earth on its axis. • Spins faster at the equator than the poles • Hot air collects, rises and moves north & south to cooler areas • Cells- huge areas distinguished by direction of air movement • Prevailing Winds – different directions of air movement • Blow continuously, distribute heat & moisture around Earth, drive ocean currents

8. Factors That Determine How Air Circulates • Properties of air, water, & land • Sun evaporates water  transfer of heat from oceans to atmosphere  creation of convection cells  vertical circulation of air, heat, moisture

9. Ocean Currents • Mass movement of surface water in the oceans • Created by heat from the sun and changes in water density • Warm currents are shallow and less salty • Cold currents are deeper and salty • Driven by prevailing winds and Earth’s rotation • Interrupted by continents

10. Air, Water, & Climate • Air circulation patterns, prevailing winds, the configuration of continents, and ocean currents form 6 giant cells (3 above/3 below the equator) • These lead to the uneven distribution of heat & moisture, resulting in varying climates, and biomes • Deserts, grasslands, forests, etc.

11. Earth’s Surface & Microclimates • Climate near Large Bodies of Water • Water absorbs /releases heat slower than land • Oceans/Lakes moderate weather & climate of nearby land by absorbing solar radiation • Climates of Cities • Bricks, concrete, asphalt absorb & hold heat • Building block wind flow • Vehicles & heating/cooling systems release large amounts of heat & pollutants • All these cause more haze/smog  increase temperatures  decrease in wind speeds

12. Earth’s Surface & Microclimates • Climate near Mountains • Mountains interrupt the flow of prevailing winds/storms forcing them upwards • Upward = cooling moisture condenses/falls on the windward slope • Dry air passes over mountain and flows down the leeward slope & warms • Rain shadow effect formation of deserts (Death Valley)

13. Greenhouse Gases Keep Us Warm • Greenhouse gases: water, carbon dioxide, nitrous oxides, methane present in the lower atmosphere. • Natural Greenhouse effect: natural warming effect of the troposphere. • Allows life to be sustained on Earth • Human acts are increasing the amount of greenhouse gases in the atmosphere by: • Burning fossil fuels • Clearing forests (deforestation) • Growing crops/raising cattle

15. Introduction to Weather

16. Fronts • Front: a boundary between two air masses with different temperatures and densities. • Warm Front • Warm air advances on cool air  warm air is less dense at slide atop the cool air forms condensation (clouds)  clouds thicken & descend  precipitation • Causes cloudy skies and drizzle • Cold Front • Cold air advances on warm air  cold air is more dense and wedges below the warm air  produces tall thunderbolt clouds • Causes high winds and thunderstorms but leaves clear skies and cooler temps

18. Jet Streams • Jet streams: rapidly flowing air current (strong winds) that move east to west in a wavy pattern. • Located at the top of the troposphere • Strong influence on weather patterns

19. Atmospheric Pressure • Atmospheric Pressure- caused by the collision of high speed molecules in the air • Mostly oxygen & nitrogen • Greater at the Earth’s surface because they are squeezed under the air above them • High – air mass with high pressure • Cool dense air that slowly descends becoming warmer • Causes clear skies and fair weather • Low – air mass with low pressure • Warm air with low density rises and cools  condensation  clouds form  precipitation • Causes cloudy, stormy weather

20. Other Weather Terms • Dew point – temperature at which condensation takes place • Condensation nuclei – particles of dust, smoke, sea salts, or volcanic ash that serve as surfaces for rain to form on • Upwelling – upward movement of ocean water, mixes the upper levels and lower levels of sea water • Upper levels – warm, phytoplankton • Lower levels – nutrient rich

21. ENSO • El Nino – Southern Oscillation (ENSO) – the weakening or reversal of the tropical trade winds that normally blow east to west (Pacific Ocean) • Causes drought in Australia, S. East Asia & storms in W. United States • Can be tracked • La Nina – reverse of ENSO, normal conditions • More Atlantic hurricanes, colder winter in Canada and NE United States, rains SE Asia

22. Extreme Weather • Tornadoes – over land • Form when large, dry cold front runs into a mass of warm, humid air • Tropical Cyclones – over ocean • Hurricanes (Atlantic), Typhoons (Pacific) • Form when low pressure cells grow over warm tropical waters

23. Terrestrial Biomes

24. The most important factors in a biome are temperature and precipitation. • Biomes tend to converge around latitude lines on the globe.

25. Terrestrial Biomes

26. Deserts • The evaporation is greater than the precipitation (usually less than 25 cm/year). • Covers 30% of the earth.

27. Types of Desert Biomes • Variations in annual temperature (red) and precipitation (blue) in tropical, temperate and cold deserts.

28. Grasslands • The rainfall is erratic & fires are common. It has & shrubs that are good for grazing animals.

29. Types of Grassland Biomes • Variations in annual temperature (red) and precipitation (blue) in tropical, temperate and cold deserts.

30. Savanna • The tropical & subtropical grassland. • It is warm all year long with alternating wet & dry seasons.

31. Chaparral • Temperate Grasslands • These are coastal areas. Winters are mild & wet, w/ summers being long, hot, & dry. • Chaparral has a moderate climate but its dense thickets of spiny shrubs are subject to periodic fires

32. Prairies • Temperate Grassland • The cold winters and hot dry summers have deep and fertile soil that make them ideal for growing crops and grazing cattle.

33. Tundra • Polar Grassland • Covers 10% of earth’s land. Most of the year, these treeless plains are bitterly cold with ice & snow. It has a 6 to 8 week summer w/ sunlight nearly 24 hours a day. • covered with ice and snow except during a brief summer.

34. Forests • Forests have enough precipitation to support stands of trees and are found in tropical, temperate, and polar regions.

35. Taiga (evergreen coniferous forest) • Just south of the tundra (northern part of N. America), it covers 11% of earth’s land. Its winters are long, dry & cold. Some places have sunlight 6 to 8 hours a day. The summers are short and mild, w/ sunlight 19 hours a day.

36. Taiga (evergreen coniferous forest) • High-elevation islands of biodiversity • Often have snow-covered peaks that reflect solar radiation and gradually release water to lower-elevation streams and ecosystems.

37. Taiga (evergreen coniferous forest) • Consist mostly of cone-bearing evergreen trees that keep their needles year-round to help the trees survive long and cold winters

38. Tropical Rainforest • Near the equator. It has warm temperatures, high humidity & heavy rainfall. • Tropical rain forests have heavy rainfall and a rich diversity of species. • Found near the equator. • Have year-round uniformity warm temperatures and high humidity

39. Tropical Rainforest

40. Temperate Rain Forests • Coastal areas support huge cone-bearing evergreen trees such as redwoods and Douglas fir in a cool moist environment

41. Temperate Deciduous Forest • It has moderate temperatures, long, warm summers, cold winters &lots of rain. Trees include oaks, hickory, maple, and beech. • Most of the trees survive winter by dropping their leaves, which decay and produce a nutrient-rich soil.

42. Temperate Deciduous Forest

43. Threats to Major Biomes

44. Forest Ecosystems • Forests = ~ 30% of Earth’s land surface • Types of Forests: • Old-growth/Primary Forests: uncut or regenerated forest that has not been seriously disturbed • Very diverse • Second-growth Forests: resulting from secondary ecological succession • Tree plantation/tree farm/commercial forest: managed forests containing one or two species of trees, all the same age • Less diversity

45. Natural Capital of Forests Ecological Services Economic Services Fuel wood Lumber Pulp for paper Mining Livestock grazing Recreation Jobs • Support energy flow and chemical cycling • Reduce soil erosion • Absorb/release water • Purify water/air • Influence climate • Store atmospheric carbon • Provide wildlife habitats

46. Threats to Forests • Clearing for agriculture, livestock grazing, timber, and urban development • Conversion of diverse forests to tree plantations • Damage from off-road vehicles • Pollution of forest streams • Forest fires • Insects • Climate change

47. Clear-Cutting • Selective Cutting: older trees cut singularly or in small groups • Clear-Cutting: removing all trees from an area • Advantages: higher timber yields, maximum profits, reforest with fast growing trees, good for trees needing full/moderate sunlight • Disadvantages: reduces biodiversity, destroys/fragments habitats, increases water pollution, flooding, erosion, eliminates recreational value.

48. Forest Fires • Surface fires: burn undergrowth and leaf litter on forest floor • Kills seedlings, small trees, mature trees and most animals escape • Helps prevent more serious fires • Free up valuable nutrients • Release seeds from cones • Control disease & insects • Crown fire: extremely hot fire that goes from treetop to treetop, burning whole trees • Destroy most vegetation/wildlife, increase soil erosion, burn human structures • Not major long term threat, promotes secondary succession • Serious short term threats- habitat loss, increased CO2 & other pollutants

49. Deforestation • Temporary for permanent removal of large areas of forest • Decreased soil fertility from erosion • Runoff leads to more soil in aquatic ecosystems • Premature extinction of specialized species • Loss of habitat • Regional climate change • Increase of CO2 in atmosphere • Acceleration of flooding

50. Destruction of Tropical Forests • Roads • Fires • Settler Farming • Cash crops • Cattle ranching • Logging • Tree plantation