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

5. TODAY: Aquatic Biomes Terrestrial 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

6. Varying combinations of both biotic and abiotic factors
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

7. 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
200 m
Continental shelf
Pelagic
zone
2,500–6,000 m
Abyssal zone (deepest regions of ocean floor)
(b)
Figure 50.16a, b

8. 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
An oligotrophic lake in Grand Teton, Wyoming
A eutrophic lake in Okavango delta, Botswana
LAKES
Figure 50.17

9. 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

10. 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

11. 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

12. Rocky intertidal zone on the Oregon coast
Intertidal Zones
INTERTIDAL ZONES
Rocky intertidal zone on the Oregon coast
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

13. 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)
Open ocean off the island of Hawaii
OCEANIC PELAGIC BIOME

14. 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
A coral reef in the Red Sea
CORAL REEFS

15. A deep-sea hydrothermal vent community
Marine benthic
A deep-sea hydrothermal vent community
MARINE BENTHIC ZONE
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

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

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

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

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

20. A tropical rain forest in Borneo
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

21. The Sonoran Desert in southern Arizona
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

22. A typical savanna in Kenya
distribution: equatorial, subequatorial
precipitation: 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
human impact: cattle ranching, overhunting
SAVANNA
A typical savanna in Kenya

23. An area of chaparral in California
distribution: midlatitude coastal regions
precipitation: rainy winters, dry summers; 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)
human impact: agriculture,urbanization
CHAPARRAL
An area of chaparral in California

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

25. Rocky Mountain National Park in Colorado
Coniferous forest
Rocky Mountain National Park in Colorado
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

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

27. Denali National Park, Alaska, in autumn
Tundra
distribution: arctic (20% of surface)
precipitation: 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
human impact: mineral, oil extraction
TUNDRA
Denali National Park, Alaska, in autumn

28. 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.

29. 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.

30. 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.

31. 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.