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Chapter 50

Chapter 50. An Introduction to Ecology and the Biosphere (cont’d). RECALL:. Concept 50.1: Ecology is the study of interactions between organisms and the environment Concept 50.2: Interactions between organisms and the environment limit the distribution of species

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Chapter 50

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  1. Chapter 50 An Introduction to Ecology and the Biosphere (cont’d)

  2. RECALL: • Concept 50.1: Ecology is the study of interactions between organisms and the environment • Concept 50.2: Interactions between organisms and the environment limit the distribution of species • Concept 50.3: Abiotic and biotic factors influence the structure and dynamics of aquatic biomes

  3. Aquatic Biomes Lakes Wetlands Streams Rivers Estuaries Intertidal biomes Oceanic pelagic biomes Coral reefs Marine benthic biomes Terrestrial Biomes Tropical Forests Deserts Savanna Chaparrals Temperate Grasslands Coniferous Forest Temperate Broadleaf Forests Tundra TODAY:

  4. Concept 50.3: Abiotic and biotic factors influence the structure and dynamics of aquatic biomes • Varying combinations of both biotic and abiotic factors • determine the nature of Earth’s many biomes • Biomes • are the major types of ecological associations that occupy broad geographic regions of land or water

  5. Intertidal zone Neritic zone Oceanic zone Littoralzone Limneticzone 0 Photic zone 200 m Continentalshelf Pelagic zone Benthiczone Aphoticzone Photiczone Pelagiczone Benthiczone Aphoticzone (a) Zonation in a lake. The lake environment is generally classified on the basis of three physical criteria: light penetration (photic and aphotic zones), distance from shore and water depth (littoral and limnetic zones), and whether it is open water (pelagic zone) or bottom (benthic zone). 2,500–6,000 m Abyssal zone(deepest regions of ocean floor) (b) Marine zonation. Like lakes, the marine environment is generally classified on the basis of light penetration (photic and aphotic zones), distance from shore and water depth (intertidal, neritic, and oceanic zones), and whether it is open water (pelagic zone) or bottom (benthic and abyssal zones). Aquatic zones • Many aquatic biomes • are stratified into zones or layers defined by light penetration, temperature, and depth Figure 50.16a, b

  6. LAKES An oligotrophic lake in Grand Teton, Wyoming A eutrophic lake in Okavango delta, Botswana Lakes • physical environment: standing body of water; can be stratified; seasonal thermocline • chemical environment:oligotrophic = deep, nutrient-poor, oxygen rich; eutrophic lakes = shallower, increased nutrients, oxygen depleted in winter; mesotrophic = moderate amount of nutrients, phytoplankton productivity • geologic features: oligotrophic lakes have less surface area compared to depth; oligotrophic lake can become eutrophic over time • photosynthetic organisms: ps. rates higher in eutrophic lakes; plants in littoral zone; phytoplankton + cyanobacteria in limnetic zone • animals: zooplankton in limnetic zone; invertebrates in benthic zone; fish present throughout if O2 present • human impact: runoff from fertilizers, dumping of municipal waste = nutrient enrichment – algal blooms, O2 depletion Figure 50.17

  7. Wetlands • physical environment: area covered with water for long enough period to support aquatic life • chemical environment: high organic production, decomposition;low dissolved O2 • geologic features: basin wl.= shallow basin; riverine wl. = shallow, flooded banks of rivers, streams; fringe wl. = along coasts of lakes, seas depending on tides • photosynthetic organisms: plants with adaptations to grow in water with low O2 • animals: invetebrates – birds; herbivores, carnivores • human impact: draining & filling destroyed up to 90% of wl. in some regions WETLANDS Okefenokee National Wetland Reserve in Georgia

  8. STREAMS AND RIVERS A headwater stream in theGreat Smoky Mountains The Mississippi River farform its headwaters Streams and Rivers • physical environment: current; headwater streams = cold, clear, turbulent; downstream = warmer, more turbid; stratified • chemical environment: salt, nutrient content increases from headwater to mouth; headwater O2 rich • geologic features: headwater narrow, rocky bottom; downstream – wider, bottom silty • photosynthetic organisms: streams through grassland or dessert are rich in algae or rooted plants; in forests leaves etc. from terrestrial plants primary food source for consumers • animals: fishes, invertebrates • human impact: municipal, agricultural, industrial pollution, damming

  9. ESTUARIES An estuary in a low coastal plain of Georgia Estuaries • physical environment: transition area between river & sea; complex flow patterns; higher density sea water bottom of estuary channel • chemical composition: salinity variable; nutrient from river make estuaries very productive • geologic features: tidal channels, islands, levees, mudflats • photosynthetic organisms: grasses, algae including phytoplankton • animals: invertebrates, fishes; important breeding grounds for marine species; feeding area for waterfowl • human impact: pollution from upstream, filling, dredging

  10. INTERTIDAL ZONES Rocky intertidal zone on the Oregon coast Intertidal Zones • physical environment: periodically submerged & exposed by tides; upper zones greater exposure to air, more variation in environment (temp., salinity, wave action) • chemical environment: O2, nutrient levels high • geologic features: rocky or sandy substrate; variable influence of tides depending on coastline • photosynthetic organisms: attached marine algae • animals: invertebrates with special adaptations to attach to substrate • human impact: oil pollution, recreational use

  11. OCEANIC PELAGIC BIOME Open ocean off the island of Hawaii Ocean pelagic biome • physical environment: open water, mixed by ocean currents; higher clarity that coastal zones, photic zone is deeper • chemical environment: O2 high; nutrient levels low; temperate regions there is surface turn over • geologic features: vast, deep waters; 70% of Earth’s surface • photosynthetic organisms: phytoplankton • animals: zooplankton, free swimming invertebrates, vertebrates • human impact: overfishing, pollution (oil spills, waste dumping)

  12. CORAL REEFS A coral reef in the Red Sea Coral reefs • physical environment: limited to photic zones of stable tropical environments with high water clarity • chemical environment: high O2, stable salinity, stable nutrient levels • geologic features: coral reef formed from calcium carbonate of corals; needs solid substrate • photosynthetic organisms: dinoflagellate algae within tissues of corals; red, green marine algae • animals: cnidarians predominant animals; fish, invertebrates • human impact: poisons, explosives for aquarium trade, global warming, pollution

  13. MARINE BENTHIC ZONE A deep-sea hydrothermal vent community Marine benthic • physical environment: seafloor below neritic zone (WATER THAT IS ABOVE THE CONTINETIAL SHELF & pelagic zone; no sunlight in benthos beneath pelagic; deep benthic = abyssal zone (cold 3ºC, high pressure) • chemical environment: O2 sufficient for diversity of animals • geologic features: soft sediments; some rocky substrate; submarine mountains; volcanoes • food producing organisms: ps organisms only in shallow benthos; some organisms associated with deep-sea hydrothermal vents- chemoautotrophic prokaryotes • animals: neritic benthic – invertebrates, fishes; deep water tube worms; arthropods, echinoderms • human impact: overfishing, dumping

  14. Concept 50.4: Climate largely determines the distribution and structure of terrestrial biomes • Climate • is particularly important in determining why particular terrestrial biomes are found in certain areas

  15. Temperate grassland Desert Tropical forest 30 Temperate broadleaf forest 15 Annual mean temperature (ºC) Coniferous forest 0 Arctic and alpine tundra 15 100 200 300 400 Annual mean precipitation (cm) Climate and Terrestrial Biomes • Climate has a great impact on the distribution of organisms, as seen on a climograph Figure 50.18

  16. 30N Tropic of Cancer Equator Tropic of Capricorn 30S Chaparral Tundra Key Temperate grassland High mountains Tropical forest Temperate broadleaf forest Polar ice Savanna Coniferous forest Desert The distribution of major terrestrial biomes Figure 50.19

  17. General Features of Terrestrial Biomes • Terrestrial biomes • are often named for major physical or climatic factors and for their predominant vegetation • Stratification • is an important feature of terrestrial biomes

  18. TROPICAL FOREST A tropical rain forest in Borneo Tropical forest • distribution: equatorial, subequatorial • precipitation: tropical rain forests -relatively constant, 200-400 cm annually; tropical dry forests – 150-200 cm annually (6-7 month dry season) • temperature: 25-29ºC • plants: stratified – canopy, subcanopy trees; rain forest -broadleaf evergreen dominant; deciduous broadleaf in tropical dry forest • animals: most animal diversity than any other terrestrial biome • humanimpact: destruction for agriculture, development

  19. DESERT The Sonoran Desert in southern Arizona Desert • distribution: in band near 30º N & S latitude or interior of continents • precipitation: low, highly variable; less than 30 cm per year • temperature: variable; can exceed 50ºC; some cold deserts -30ºC • plants: low, scattered vegetation; high proportion of bare ground; succulents, shrubs • animals: reptiles, rodents, insects; many species nocturnal; adaptations to deal with scarce water • humanimpact: conversion to irrigated land, urbanization

  20. SAVANNA A typical savanna in Kenya Savanna • distribution: equatorial, subequatorial • precipitation: 30-50 cm per year; dry season 8-9 months • temperature: 24-29ºC • plants: scattered trees; adapted for seasonal drought; grasses + forbs dominant • animals: large herbivores; insects • humanimpact: cattle ranching, overhunting

  21. CHAPARRAL An area of chaparral in California Chaparral • distribution: midlatitude coastal regions • precipitation: rainy winters, dry summers; 30-50 cm annual • temperature: fall, winter, spring 10-12ºC; summer 30-40ºC • plants: shrubs, small trees; high plant diversity; adaptations to drought • animals: browsing herbivores, high diversity of small animals (amphibians, birds, reptiles) • humanimpact: agriculture,urbanization

  22. TEMPERATE GRASSLAND Sheyenne National Grassland in North Dakota Temperate grasslands • distribution: throughout various regions • precipitation: dry winters, wet summers; 30-100 cm • temperature: cold winters -10ºC; hot summers 30ºC • plants: grasses & forbs; adapted to drought, fire • animals: large grazers, burrowing animals • humanimpact: agriculture

  23. CONIFEROUS FOREST Rocky Mountain National Park in Colorado Coniferous forest • distribution: broad band across northern N America & Erasia to edge of arctic tundra • precipitation: 30-70 cm, periodic droughts; coastal coniferous forests 300 cm • temperature: winters cold, long; summers may be hot • plants: cone-bearing trees • animals: large herbivores, carnivores • humanimpact: logging

  24. TEMPERATE BROADLEAF FOREST Great Smoky Mountains National Park in North Carolina Temperate broadleaf forest • distribution: midlatitude in northern hemisphere • precipitation: 70-200 cm annually • temperature: winter 0ºC; summers 30ºC • plants: high diversity; deciduous trees dominant • animals: mammals, birds, insects • humanimpacts: logging, agriculture, urban developement Figure 50.20

  25. TUNDRA Tundra • distribution: arctic (20% of surface) • precipitation: 20-60 cm; some areas 100 cm • temperature: winters long, cold -30ºC; summers short cool 10ºC • plants: herbaceous (lichens, mosses, grasses, forbs, dwarf trees); permafrost prevents water infiltration into soil • animals: large grazing herbivores, large carnivores, migratory birds • humanimpact: mineral, oil extraction Denali National Park, Alaska, in autumn

  26. Take home questions: Which of the following statements best describes the effect of climate on biome distribution? • Knowledge of annual temperature and precipitation is sufficient to predict which biome will be found in an area. • Fluctuation of environmental variables is not important if areas have the same annual temperature and precipitation means. • It is not only the average climate that is important in determining biome distribution, but also the pattern of climatic variation. On final Test. • Temperate forests, coniferous forests, and grasslands all have the same mean annual temperatures and precipitation. • Correlation of climate with biome distribution is sufficient to determine the cause of biome patterns.

  27. Imagine some cosmic catastrophe that jolts Earth so that it is no longer tilted. Instead, its axis is perpendicular to the line between the Sun and Earth. The most predictable effect of this change would be: • No more night and day. • A big change in the length of the year. • A cooling of the equator. • A loss of seasonal variations at northern and southern latitudes. In the textbook. • The elimination of ocean currents.

  28. Which of the following events might you predict to occur if the tilt of Earth's axis relative to its plane of orbit was increased beyond 23.5 degrees? • Summers in the United States might become warmer. • Winters in Australia might become more severe. • Seasonal variation at the equator might decrease. • Both A and B are correct. • A, B, and C are all correct.

  29. If a meteor impact or volcanic eruption injected a lot of dust into the atmosphere and reduced sunlight reaching Earth's surface by 70% for one year, all of the following marine communities would be greatly affected except a • deep-sea vent community. • coral reef community. • benthic community. • pelagic community. • estuary community.

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