Presentation on theme: "Chapter 50 An Introduction to Ecology and the Biosphere (contd)"— Presentation transcript:
Chapter 50 An Introduction to Ecology and the Biosphere (contd)
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
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 Earths many biomes Biomes – are the major types of ecological associations that occupy broad geographic regions of land or water
Aquatic zones Many aquatic biomes – are stratified into zones or layers defined by light penetration, temperature, and depth 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). 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). (a) Littoral zone Limnetic zone Photic zone Benthic zone Aphotic zone Pelagic zone Intertidal zone Neritic zone Oceanic zone m Continental shelf Photic zone Pelagic zone Aphotic zone Benthic zone 2,500–6,000 m Abyssal zone (deepest regions of ocean floor) (b) Figure 50.16a, b
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 An oligotrophic lake in Grand Teton, Wyoming A eutrophic lake in Okavango delta, Botswana LAKES
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
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 STREAMS AND RIVERS A headwater stream in the Great Smoky Mountains The Mississippi River far form its headwaters
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 An estuary in a low coastal plain of Georgia ESTUARIES
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 INTERTIDAL ZONES Rocky intertidal zone on the Oregon coast
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 Earths surface photosynthetic organisms: phytoplankton animals: zooplankton, free swimming invertebrates, vertebrates human impact: overfishing, pollution (oil spills, waste dumping) Open ocean off the island of Hawaii OCEANIC PELAGIC BIOME
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 A coral reef in the Red Sea CORAL REEFS
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 A deep-sea hydrothermal vent community MARINE BENTHIC ZONE
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
Climate and Terrestrial Biomes Climate has a great impact on the distribution of organisms, as seen on a climograph Figure Desert Temperate grassland Tropical forest Temperate broadleaf forest Coniferous forest Arctic and alpine tundra Annual mean precipitation (cm) Annual mean temperature (ºC)
The distribution of major terrestrial biomes 30 N Tropic of Cancer Equator Tropic of Capricorn 30 S Key Tropical forest Savanna Desert Chaparral Temperate grassland Temperate broadleaf forest Coniferous forest Tundra High mountains Polar ice Figure 50.19
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
Tropical forest distribution: equatorial, subequatorial precipitation: tropical rain forests -relatively constant, cm annually; tropical dry forests – 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 human impact: destruction for agriculture, development TROPICAL FOREST A tropical rain forest in Borneo
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 human impact: conversion to irrigated land, urbanization DESERT The Sonoran Desert in southern Arizona
Savanna distribution: equatorial, subequatorial precipitation: cm per year; dry season 8-9 months temperature: º C plants: scattered trees; adapted for seasonal drought; grasses + forbs dominant animals: large herbivores; insects human impact: cattle ranching, overhunting SAVANNA A typical savanna in Kenya
Chaparral distribution: midlatitude coastal regions precipitation: rainy winters, dry summers; cm annual temperature: fall, winter, spring º C; summer º C plants: shrubs, small trees; high plant diversity; adaptations to drought animals: browsing herbivores, high diversity of small animals (amphibians, birds, reptiles) human impact: agriculture,urbanization CHAPARRAL An area of chaparral in California
Temperate grasslands distribution: throughout various regions precipitation: dry winters, wet summers; cm temperature: cold winters -10 º C; hot summers 30 º C plants: grasses & forbs; adapted to drought, fire animals: large grazers, burrowing animals human impact: agriculture Sheyenne National Grassland in North Dakota TEMPERATE GRASSLAND
Coniferous forest distribution: broad band across northern N America & Erasia to edge of arctic tundra precipitation: cm, periodic droughts; coastal coniferous forests 300 cm temperature: winters cold, long; summers may be hot plants: cone-bearing trees animals: large herbivores, carnivores human impact: logging Rocky Mountain National Park in Colorado CONIFEROUS FOREST
Temperate broadleaf forest distribution: midlatitude in northern hemisphere precipitation: cm annually temperature: winter 0 º C; summers 30 º C plants: high diversity; deciduous trees dominant animals: mammals, birds, insects human impacts: logging, agriculture, urban developement Figure TEMPERATE BROADLEAF FOREST Great Smoky Mountains National Park in North Carolina
Tundra distribution: arctic (20% of surface) precipitation: cm; some areas 100 cm temperature: winters long, cold -30 º C; summers short cool 10 º C plants: herbaceous (lichens, mosses, grasses, forbs, dwarf trees); permafrost prevents water infiltration into soil animals: large grazing herbivores, large carnivores, migratory birds human impact: mineral, oil extraction TUNDRA Denali National Park, Alaska, in autumn
Take home questions: Which of the following statements best describes the effect of climate on biome distribution? A)Knowledge of annual temperature and precipitation is sufficient to predict which biome will be found in an area. B)Fluctuation of environmental variables is not important if areas have the same annual temperature and precipitation means. C)It is not only the average climate that is important in determining biome distribution, but also the pattern of climatic variation. On final Test. D)Temperate forests, coniferous forests, and grasslands all have the same mean annual temperatures and precipitation. E)Correlation of climate with biome distribution is sufficient to determine the cause of biome patterns.
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: A)No more night and day. B)A big change in the length of the year. C)A cooling of the equator. D)A loss of seasonal variations at northern and southern latitudes. In the textbook. E)The elimination of ocean currents.
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? A)Summers in the United States might become warmer. B)Winters in Australia might become more severe. C)Seasonal variation at the equator might decrease. D)Both A and B are correct. E)A, B, and C are all correct.
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 A)deep-sea vent community. B)coral reef community. C)benthic community. D)pelagic community. E)estuary community.