Notes Chapter 5: Climate and Terrestrial Biodiversity

1. Notes Chapter 5: Climate and Terrestrial Biodiversity Focus Questions: • What factors influence earth’s climate? • How does climate determine where the earth’s major biomes are found? • What are the major types of desert biomes? • What are the major types of grassland biomes? • What are the major types of forest and mountain biomes? • How have human activities affected, the world’s desert, grassland, forest, and mountain biomes?

2. Case StudyBlowing in the Wind: A Story of Connections • Wind • Vital part of planet’s circulatory system • Distributes heat • Transports heat (P and Fe in dust) • Bad News • Dust storms in Sahara increased 5 to 10-fold since 1950. • Climate change and overgrazing

3. SUV connection • Transports viruses, bacteria, fungi, and particles of long-lived pesticides and toxic metals. • More bad news • Some agents (perhaps fungi) may be killing corals, FL Keys and Caribbean • Increase in asthma in Caribbean since 1973 • Fe rich dust may trigger harmful algal blooms, FL • Pollution and dust form China and C. Asia blows across Pacific Ocean reduce air quality in W US

4. Mixed News • Particles from volcanic eruptions decrease global temp. • Add trace elements to soil. • Familiar Lesson • No away • Everything is connected • Wind: circulates heat, moisture, plant nutrients, long-lived air pollutants, and soil particles • Global air circulation patterns influence climate; climate influences plants and animals found in biomes.

5. I. Climate: A Brief Introduction • Weather – temp., precipitation, humidity, wind speed, cloud cover, and physical conditions over hours or days (see Suppl. 10). • Climate – region’s general weather patterns over a long period of time. • Average temperature and precipitation • Latitude and elevation

6. Earth’s Major Climate Zones (Fig. 5-2) Back to Ocean Currents

7. Solar Energy and Global Air Circulation: Distributing Heat • Factors that contribute to local climate: • Amount of solar radiation • Motion of the earth – rotation and revolution • Air circulation patterns • Distribution of land masses and seas • Ocean currents • Elevation of land masses

8. Four factors that determine global circulation patterns. • Uneven heating of the earth’s surface • Seasonal changes in temperature and precipitation (Fig. 5-3) • Rotation of earth on its axis • Coriolis effect (animation) • Cells – air movement in huge regions (Fig. 5-4) • Prevailing winds Coriolis Web Animation http://www.wiley.com/college/strahler/0471480533/animations/ch07_animations/animation2.html

9. Properties of air, water, and land • Cyclical convection cells circulate air, heat, and moisture vertically (Fig. 5-5). • Six giant cells, 3 in N hemisphere and 3 in S (Fig. 5-6) • Leads to irregular distribution of climate patterns and vegetation (or biomes).

10. Ocean Currents: Distributing Heat and Nutrients • Ocean currents affect climate of regions (Fig. 5-2) • Ocean absorbs heat, bulk near equator • Temperature differences influence vertical movements • Temperature and winds influence horizontal movements. • Distributes heat • Distributes nutrients – upwellings (see Fig. 5-2 and Suppl. 10) • Mix Water • Nutrients • Oxygen

11. Atmospheric Gases and Climate: The Natural Greenhouse Effect • Certain gases regulate earth’s average temp. • CO2, CH4, H2O, and N2O • Greenhouse gases cause greenhouse effect (Fig. 5-7). • Human activities increasing greenhouse effect • Evidence and climate models indicate anthropogenic climate change. • Alter precipitation • Shift areas where crops can grow • Raise sea levels • Change where plants and animals live (or cause extinctions)

12. Topography and Local Climate: Land Matters • Large bodies of water moderate climate of nearby lands • Sea breezes • Rainshadow effect (Fig. 5-8) • Monsoons – heavy rains experienced by land masses lying north and south of warm oceans. • Alternating wet and dry seasons • Heating of land  low pressure  draws moisture from warm ocean • Microclimates of cities – warmer than surrounding countryside. • Haze, smog, higher temp, lower wind speed

13. II. Biomes: Climate and Life on Land • Why Do Different Organisms Live in Different Places? • Difference in climate  different organisms, esp. plants. • Biomes – large terrestrial regions characterized by similar climate, soil, plants, and animals. • Locations of biomes have shifted  solar output, emissions from volcanic eruptions, and continental drift. • 5000 y.a. Sahara Desert was a fertile grassland • 15000 y.a. arid American SW was rainy and had many lakes. • Compare biomes locations w/ regional climates (Fig. 5-9 and 5-2). • Biomes at the 39th parallel in NA (Fig. 3-9, p. 56)

14. Influence of humans? • Major factors that determine type of biome (Fig. 3-10): • Average annual precipitation • Average annual temperature • Soil type • Biomes are not uniform • Communities vary, but have unique attributes • Patchiness  resources not uniformly distributed and humans remove or alter vegetation. • Climate and vegetation vary similarly with latitude and elevation (Fig. 5-11).

15. III. Desert Biomes • Deserts: Tropical, Temperate, and Polar. • General Attributes • Evaporation exceeds precipitation; annual precipitation is low and scattered unevenly throughout year. • Cover 30% of land surface, mostly subtropical and tropical regions. • Largest in interior of continents, other local due to rainshadow effect. • Little water in atmosphere, vegetation, and ground  broad temperature swings between night and daytime.

16. Low rainfall and different average temperatures determine type: • Tropical desert (Fig. 5-12a) – like Sahara and Namib of Africa • Hot and dry most of year • Few plants • Hard wind blown surface w/ rock and sand. • Temperate desert (Fig. 5-12b) – like Mojave and Chihuahuan in American SW. • Daytime temperatures in summer are high and low in winter. • More precipitation than in tropical deserts • Sparse vegetation, mostly shrubs, cacti, and succulent adapted to low water availability and temperature variation.

17. Polar Desert (Fig. 5-12c) – Gobi in China • Winters, cold; summers warm or hot • Precipitation is low • How do desert plants and animals survive? • General strategies • Adaptive strategies to reduce thermal stress • Conserve water • Desert plants • Drop leaves, as in mesquite and creosote • Succulent plants • No or reduced leaves • Store water and synthesize food in fleshy tissue • Open stomata only at night • Spines guard from being eaten by herbivores

18. Deep taproots as in mesquite • Widely spread, shallow roots to collect water when available. • Evergreens have waxy cuticle • Annuals, grasses and wildflowers store much biomass as dormant seed for next rainfall. • Desert Animals • Small, nocturnal (hiding in burrows or rocky crevices during day). • Aestivation • Concentrate urine • Thick cuticles in insects and reptiles • Water in food and metabolic water • Drink dew droplets that accumulate an night

19. Desert ecosystems are fragile (Fig. 5-13). • Soils take a long time to recover. Why? • Slow plant growth • Low species diversity • Slow nutrient cycling • Lack of water

20. IV. Grasslands and Chaparral Biomes • Types of Grasslands • Grasslands, or prairies, occur mostly in the interiors of continents too moist for deserts and too dry for forests. • Reason for occurrence • Seasonal drought • Grazing by large herbivores • Occasional fires • Three types of grasslands: tropical, temperate, and polar (tundra) • Results form combinations of low precipitation and various average temperatures

21. Tropical Grasslands: Savannas (Fig. 5-14a) • Savanna – tropical grassland w/ scattered clumped trees such as acacia. • Usu. Warm year-round w/ alternating wet and dry seasons (graph). • Lightning and heavy grazing inhibit growth of trees and shrubs. • It’s the birthplace of mankind • In dry locations of Africa, Australia, India, and S.A.

22. Fauna • Farsighted, swift, and stealthy • Examples: East Africa’s grazers and browsers (gazelles, zebras, giraffes, and antelope) and their predators (lions, hyenas, and humans). • Large herds migrate to find food and water. • Large herbivores have evolved specialized diets to minimize competition. • Giraffes eat leaves and shoots from tree tops. • Elephants eat leaves and branches from lower tree parts. • Wildebeests prefer short grass. • Zebra graze on longer grasses and stems.

23. Flora adapted to survive drought and extreme heat and cold. • Deep roots that can tap into ground water. • Savannas in Africa have rapidly growing human populations • Rapid conversion to rangeland for cattle • Overgrazing by domesticated grazers and use of trees for firewood  savanna to desert.

24. Temperate Grasslands: Fertile Soils (Fig. 5-15) • Once covered vast expanses of plains and gently rolling hills in the interiors of NA, SA, Europe, and Asia (Fig. 5-14b). • NA prairies • Steppes of Eurasia • Pampas of SA • Winters, bitterly cold; summers, hot and dry; precipitation is fairly sparse (graph). • Drought and occasional fires inhibit growth of trees and bushes, except along rivers and streams.

25. Above ground grass shoots die producing fertile soils. • Top soil is held in place by thick network of intertwined roots. • What effect does plowing have? • Native grasses, adapted to fires. • Temperate grasslands once covered large areas of earth. • Fertile soil used for crops (Fig. 5-16), cattle, and suburban- and urbanization.

26. Polar Grasslands: Arctic Tundra • Most of year, treeless plains are bitterly cold, swept by frigid winds, and covered with ice and snow. • Precipitation is scant and mostly in form of snow. • Sometimes referred to as polar desert (Fig. 5-14c). • Flora • Thick spongy mat of low-growing plants • Grasses • Moses • Lichens • Dwarf shrubs • Most growth occurs during 6-8 wk summer (Fig. 5-17).

27. Permafrost – underground soil in which captured water stays frozen for more than two consecutive. • During brief summer the permafrost layer keeps the melted snow and ice from soaking into the ground. • Waterlogged tundra forms large number of shallow lakes, marshes, bogs, ponds, and seasonal wetlands. • Abundant “sqeeters” and other insects serve as food for migrating birds. • Fauna • Adaptations such as thick fur (wolf, arctic fox, musk oxen), feathers (snowy owl), and arctic lemmings.

28. Global warming  melting permafrost  release of CH4 from soil. • Fragile because of short growing season  long time for tundra soil to recover. • Oil drilling, pipelines, mines, and military bases leave scars that persist for centuries. • Alpine tundra – occur between snowline and treeline. • Vegetation similar, but more sunlight and no permafrost. • During brief summer alpine tundra can be covered w/ wildflowers.

29. Temperate Shrublands: Chaparral (Fig. 5-18) • Coastal areas on land that borders deserts  longer winter rainy season than nearby desert. • Fogs during spring and fall reduce evaporation. • Geography: S. CA, USA; Mediterranean; C Chile; S Australia; and SW Africa • Flora • Dense growth • Low-growing evergreen shrubs and occasional small trees w/ leathery leaves (reduces evaporation)

30. Fauna • Mule deer • Chipmunks • Jackrabbits • Lizards • Various birds • Long, warm and dry summer  highly flammable veg. • Fire resistant root and seed that need to be heated to germinate. • Big ecological footprint – folks like homes in nice climate • Mild, wet winters and warm, dry summers • Fires and mudslides make these areas a risky place to live.

31. V. Forest Biomes • Forest biomes • Moderate to high precipitation • Trees, shrubs, and herbs • Three types result from combinations of amount of precipitation and average temperatures. • Tropical forests • Temperate forests • Polar (or boreal) forests

32. Tropical Rainforests: Threatened Centers of Biodiversity with Poor Soils (Fig. 5-20) • Description • Near equator • Uniformly warm temperatures year-round (Fig. 5-19a) • High humidity • Heavy rainfall almost daily • High biodiversity

33. Biota • 2% of the earth’s surface, but an estimated half of the planet’s terrestrial species. • Dominated by lush broadleaf evergreen plants • No single tree dominates • Trees huge w/ shallow roots and wide bases (buttresses) • Tree tops form a dense canopy  Low light intensity on forest floor. • Ground level w/ little vegetation, but those plants found on bottom have enormous leaves • Vines reach tree tops and form bridges between trees • Stratification of specialized plant and animal niches (Fig. 5-21) • Much of the animal life including insects, bats, and birds live in the sunny canopy layer  abundant shelter, leaves, flowers and fruits

34. Ecosystem Dynamics • High NPP • Little wind so plants rely on pollinators and seed dispersion by animals • Decomposition of dead organic matter is rapid • Nutrients rapidly taken up and stored in plants  low nutrients in soil

35. Conservation • At least 40% of rainforests have been cleared for logging, crops, grazing, and mineral extraction. • Rate is increasing • Reduces biodiversity and accelerates global warming • Clear for crop or grazing results in: • Only a year or two of crops • Few nutrients in soil, leached during heavy rains. • Areas become shrublands

36. Tropical Dry Forests • Warm temperatures and wet and dry season • Trees height lower and canopies less dense • Much have been cleared for grazing and growing cops • Heavy rains cause severe erosion  few years of productivity, then land is abandoned.

37. Temperate Deciduous Forest: Changing with the Seasons (Fig. 5-22) • Description • Moderate average temperatures, change significantly w/ season. • Long, warm summers; cold but not too severe winters • Abundant precipitation spread evenly throughout year (Fig. 5-19b) • Dominated by broadleaf deciduous trees, drop leaves in fall and become dormant over winter; grow ‘em back in spring

38. Biota • Broadleaf deciduous trees – oak, hickory, maple, poplar, and beech. • Fewer species than tropical rain forests, but richer ground layer diversity • Once home for large predators such as bears, wolves, foxes, wildcats, and mountain lions. • Dominants mammals: white-tailed deer, squirrels, rabbits, opossums, raccoons and rodents. • Warblers, robins and other birds migrate to these forests during summer for the breeding season

39. Ecosystem Dynamics • Slower decomposition produces a storehouse of nutrients in leaf litter. • Production occurs in warmer months when photoperiod is longer.

40. Conservation • Large predators have been killed or displaced because of habitat destruction. • Many migratory birds are declining because of habitat fragmentation and destruction • These forests once covered eastern half of the US and western Europe • This biome has been disturbed by humans more than any other • Agriculture, industrialization and urbanization

41. Evergreen Coniferous Forests: Cold Winters, Wet Summers, and Conifers (Fig. 5-23) • Description • Also called boreal forests pf taigas • Just south of arctic tundra • Subarctic: Winters are long, dry and extremely cold with six to eight hours of daylight; summers are short, cool to warm and up to 19 hours of photoperiod (Fig. 5-19c). • Plant diversity low

42. Biota • Spruce, fir, cedar, hemlock, and pine that keep some of their narrow-pointed (needles) leaves year-round • Needle-shaped, waxy-coated leaved withstand intense cold and drought of winter when snow blankets ground. • Bears, wolves, moose, lynx, and burrowing rodents • Warblers and other insectivorous birds migrate there form tropics to feed on hordes of flies, mosquitoes, and caterpillars

43. Ecosystem Dynamics • Keeping needles allows advantage during brief summers, no time needed to grow new leaves. • Decomposition is slow because of low temp and high soil acidity  lead to deep layer of leaf litter and needles. • During brief summer, soil becomes waterlog forming acidic bogs, or muskegs • Southern Pine Forests • Regions of moderate climates • Economically important

44. Conservation • Tar sands being exploited in Canadian boreal forests • In southern pine forests, forests grow rapidly, cleared for wood and converted to pine plantations  reduces plant and animal diversity.

45. Temperate Rain Forests: Biodiversity Near Some Coastal Areas (Fig. 5-24) • Also called coastal coniferous forests • Scattered in coastal temperate areas w/ ample rainfall or moisture from dense ocean fogs. • Ocean moderates temp  winters mild, summers cool • Dense stands of large conifers (Sitka spruce, Douglas fir, and redwoods) once dominated undisturbed areas of along west coast of NA from n. CA to Canada • Little light reaches forest floor • Ground level frequently covered w/ mosses and ferns

46. VI. Mountain Biomes • Mountains: Islands in the Sky • Cover about ¼ of the lands surface • Dramatic changes in altitude, climate, soil, and vegetation over a short distance (Fig. 5-25) • Steep slope • Islands of biodiversity surrounded by lower-elevation landscapes transformed by human activities. • Contain the majority of world’s forests • Regulate earth’s climate • 75% of world’s freshwater stored in glaciers • Mountain tops reflect solar radiation

47. Biota • Many species are endemic • Ecosystem dynamics • Critical role in hydrologic cycle • Conservation • Prone to erosion when veg. holding soil is removed by natural disturbances (landslides and avalanches) or human activities (timber cutting and agriculture). • Serve as sanctuaries for animals driven from lowland areas. • Fate of mountain ecosystems has not been a high priority despite coming under increasing pressure from human activities.

48. VII. Human Impacts on Terrestrial Biomes • Increasing Human Disturbance • 10-55% of NPP is used, wasted, or destroyed. • Important lesson: NPP ultimately limits the number of consumers (including humans) that earth can support. • 60% of world’s major terrestrial ecosystems are being degraded or used unsustainably. • Destruction and degradation is increasing • A Survey of Our Harmful Ecological Impacts • Humans have had a number of specific harmful effects on the world’s terrestrial biomes (Figs. 5-26, 5-27, 5-28, and 5-29).

49. Seasonal Changes in Temp Back

50. Prevailing Winds Back