1. An Introduction to Ecology and the Biosphere
Chapter 52
An Introduction to Ecology and the Biosphere

2. Overview: The Scope of Ecology
Ecology is the scientific study of the interactions between organisms and the environment
These interactions determine distribution of organisms and their abundance
The Scope of Ecological Research
Ecologists work at levels ranging from individual organisms to the planet

3. Fig. 52-2a
Organismal ecology studies how an organism’s structure, physiology, and (for animals) behavior meet environmental challenges (Chapter 51)
Figure 52.2 The scope of ecological research

4. Fig. 52-2b
A population is a group of individuals of the same species living in an area
Population ecology focuses on factors affecting how many individuals of a species live in an area
Chapter 53
Figure 52.2 The scope of ecological research

5. A community is a group of populations of different species in an area
Fig. 52-2c
A community is a group of populations of different species in an area
Community ecology deals with the whole array of interacting species in a community
Chapter 54
Figure 52.2 The scope of ecological research

6. Fig. 52-2d
An ecosystem is the community of organisms in an area and the physical factors with which they interact
Ecosystem ecology emphasizes energy flow and chemical cycling among the various biotic and abiotic components
Chapter 55
Figure 52.2 The scope of ecological research

7. Northern Coniferous Forest
Fig. 52-2d
Biomes are on of the worlds’ major communities classified according to the predominant vegetation and characterized bv adaptations of organisms to that particular environment
Northern Coniferous Forest
Figure 52.2 The scope of ecological research
Coral Reef

8. A landscape is a mosaic of connected ecosystems
Fig. 52-2e
A landscape is a mosaic of connected ecosystems
Landscape ecology deals with arrays of ecosystems and how they are arranged in a geographic region
Figure 52.2 The scope of ecological research

9. The biosphere is the global ecosystem, the sum of all the planet’s ecosystems
Global ecology examines the influence of energy and materials on organisms across the biosphere
Figure 52.2 The scope of ecological research

10. Concept 52.2: Interactions between organisms and the environment limit the distribution of species
Ecologists have long recognized global and regional patterns of distribution of organisms within the biosphere
Biogeography is a good starting point for understanding what limits geographic distribution of species
Ecologists recognize two kinds of factors that determine distribution: biotic, or living factors, and abiotic, or nonliving factors

11. Kangaroos/km2 0–0.1 0.1–1 1–5 5–10 10–20 > 20 Limits of
Fig. 52-5
Kangaroos/km2
0–0.1
0.1–1
1–5
5–10
10–20
> 20
Limits of
distribution
Figure 52.5 Distribution and abundance of the red kangaroo in Australia, based on aerial surveys

12. Fig. 52-6
Ecologists consider multiple factors when attempting to explain the distribution of species
Why is species X absent
from an area?
Yes
Area inaccessible
or insufficient time
Yes
Does dispersal
limit its
distribution?
Habitat selection
Yes
Predation, parasitism,
competition, disease
Does behavior
limit its
distribution?
Chemical
factors No
Do biotic factors
(other species)
limit its
distribution?
Water
Oxygen
Salinity pH
Soil nutrients, etc. No
Do abiotic factors
limit its
distribution? No
Temperature
Light
Soil structure
Fire
Moisture, etc.
Physical
factors
Figure 52.6 Flowchart of factors limiting geographic distribution

13. Dispersal contributes to global distribution of organisms
Fig. 52-7
Current
Dispersal is movement of individuals away from centers of high population density or from their area of origin
Dispersal contributes to global distribution of organisms
1970
1966
1965
1960
1961
1958
1943
1937
1951
1956
Figure 52.7 Dispersal of the cattle egret in the Americas
1970

14. Behavior and Habitat Selection
Some organisms do not occupy all of their potential range
Species distribution may be limited by habitat selection behavior
Biotic Factors
Biotic factors that affect the distribution of organisms may include:
Interactions with other species
Predation
Competition

15. Does feeding by sea urchins limit seaweed distribution?
Fig. 52-8
Does feeding by sea urchins limit seaweed distribution?
RESULTS
100
Both limpets and urchins
removed 80
Sea urchin
Only urchins
removed 60
Seaweed cover (%)
Limpet 40
Figure 52.8 Does feeding by sea urchins limit seaweed distribution?
Only limpets removed 20
Control (both urchins
and limpets present)
August
1982
February
1983
August
1983
February
1984

16. Abiotic Factors
Abiotic factors affecting distribution of organisms include:
Temperature
Water
Sunlight
Wind
Rocks and soil
Most abiotic factors vary in space and time

17. Temperature
Environmental temperature is an important factor in distribution of organisms because of its effects on biological processes
Cells may freeze and rupture below 0°C, while most proteins denature above 45°C
Mammals and birds expend energy to regulate their internal temperature
Water
Water availability in habitats is another important factor in species distribution
Desert organisms exhibit adaptations for water conservation

18. Salinity
Salt concentration affects water balance of organisms through osmosis
Few terrestrial organisms are adapted to high-salinity habitats
Sunlight
Light intensity and quality affect photosynthesis
Water absorbs light, thus in aquatic environments most photosynthesis occurs near the surface
In deserts, high light levels increase temperature and can stress plants and animals

19. Fig. 52-9
Organisms living at high elevations are exposed to high levels of ultraviolet radiation. They face other challenges as well, including freezing temperatures and strong winds, which increase water loss and inhibit the growth of limbs on the windward side of trees
Figure 52.9 Alpine tree

20. Rocks and Soil
Many characteristics of soil limit distribution of plants and thus the animals that feed upon them:
Physical structure pH
Mineral composition
Climate
Four major abiotic components of climate are temperature, water, sunlight, and wind
The long-term prevailing weather conditions in an area constitute its climate
Macroclimate consists of patterns on the global, regional, and local level
Microclimate consists of very fine patterns, such as those encountered by the community of organisms underneath a fallen log

21. Bodies of Water
The Gulf Stream carries warm water from the equator to the North Atlantic
Oceans and their currents and large lakes moderate the climate of nearby terrestrial environments
During the day, air rises over warm land and draws a cool breeze from the water across the land
As the land cools at night, air rises over the warmer water and draws cooler air from land back over the water, which is replaced by warm air from offshore

22. Labrador current Gulf stream Equator water Warm Cold water Fig. 52-11
Figure The great ocean conveyor belt
Cold water

23. Warm air over land rises.
Fig
Air cools at
high elevation. 2
Cooler
air sinks
over water. 3
Warm air
over land rises. 1
Cool air over water
moves inland, replacing
rising warm air over land. 4
Figure Moderating effects of a large body of water on climate

24. Concept 52.3: Aquatic biomes are diverse and dynamic systems that cover most of Earth
Biomes are the major ecological associations that occupy broad geographic regions of land or water
Varying combinations of biotic and abiotic factors determine the nature of biomes
Aquatic biomes account for the largest part of the biosphere in terms of area
They can contain fresh water or salt water (marine)
Oceans cover about 75% of Earth’s surface and have an enormous impact on the biosphere

25. Tropic of Cancer Equator Tropic of Capricorn
Fig
Lakes
Coral reefs
Rivers
Oceanic
pelagic and
benthic zones
Estuaries
30ºN
Intertidal zones
Tropic of
Cancer
Equator
Tropic of
Capricorn
30ºS
Figure The distribution of major aquatic biomes

26. Stratification of Aquatic Biomes
Fig
Stratification of Aquatic Biomes
Many aquatic biomes are stratified into zones or layers defined by light penetration, temperature, and depth
Intertidal zone
Neritic zone
Oceanic zone
Littoral
zone
Limnetic
zone
Photic zone
200 m
Continental
shelf
Pelagic
zone
Benthic
zone
Aphotic
zone
Photic
zone
Pelagic
zone
Benthic
zone
Aphotic
zone
Figure Zonation in aquatic environments
2,000–6,000 m
Abyssal zone
(a) Zonation in a lake
(b) Marine zonation

27. The upper photic zone has sufficient light for photosynthesis while the lower aphotic zone receives little light
The organic and inorganic sediment at the bottom of all aquatic zones is called the benthic zone
The communities of organisms in the benthic zone are collectively called the benthos
Detritus, dead organic matter, falls from the productive surface water and is an important source of food
The most extensive part of the ocean is the abyssal zone with a depth of 2,000 to 6,000 m

28. Aquatic Biomes
Major aquatic biomes can be characterized by their physical environment, chemical environment, geological features, photosynthetic organisms, and heterotrophs

29. Oligotrophic lakes are nutrient-poor and generally oxygen-rich
Eutrophic lakes are nutrient-rich and often depleted of oxygen if ice covered in winter
Figure Aquatic biomes
An oligotrophic lake in Grand
Teton National Park, Wyoming
A eutrophic lake in the
Okavango Delta, Botswana

30. Okefenokee National Wetland Reserve in Georgia
Wetlands
A wetland is a habitat that is inundated by water at least some of the time and that supports plants adapted to water-saturated soil
Wetlands can develop in shallow basins, along flooded river banks, or on the coasts of large lakes and seas
Wetlands are among the most productive biomes on earth and are home to diverse invertebrates and birds!!!!!!!
Figure Aquatic biomes
Okefenokee National Wetland Reserve in Georgia

31. A fast current causes an increase in oxygen levels!!!!
Fig d
Streams and Rivers
The most prominent physical characteristic of streams and rivers is current
A fast current causes an increase in oxygen levels!!!!
Figure Aquatic biomes
A headwater stream in the Great
Smoky Mountains
The Mississippi River far from
its headwaters

32. An estuary is a transition area between river and sea
Fig f
Estuaries
An estuary is a transition area between river and sea
Salinity varies with the rise and fall of the tides
Estuaries are nutrient rich and highly productive
An abundant supply of food attracts marine invertebrates and fish
Figure Aquatic biomes
An estuary in a low coastal plain of Georgia

33. Fig
Concept 52.4: The structure and distribution of terrestrial biomes are controlled by climate and disturbance
Tropical forest
Savanna
Desert
Chaparral
30ºN
Tropic of
Cancer
Temperate
grassland
Equator
Temperate
broadleaf forest
Tropic of
Capricorn
Northern
coniferous forest
30ºS
Tundra
Figure The distribution of major terrestrial biomes
High mountains
Polar ice
Climate is very important in determining why terrestrial biomes are found in certain areas
Biome patterns can be modified by disturbance such as a storm, fire, or human activity

34. General Features of Terrestrial Biomes and the Role of Disturbance
Terrestrial biomes are often named for major physical or climatic factors and for vegetation
Terrestrial biomes can be characterized by distribution, precipitation, temperature, plants, and animals
Terrestrial biomes usually grade into each other, without sharp boundaries
Vertical layering is an important feature of terrestrial biomes, and in a forest it might consist of an upper canopy, low-tree layer, shrub understory, ground layer of herbaceous plants, forest floor, and root layer
Layering of vegetation in all biomes provides diverse habitats for animals
Biomes are dynamic and usually exhibit extensive patchiness

35. Tropical Forest
In tropical rain forests, rainfall is relatively constant, while in tropical dry forests precipitation is highly seasonal
Tropical forests are vertically layered and competition for light is intense
Tropical forests are home to millions of animal species, including an estimated 5–30 million still undescribed species of insects, spiders, and other arthropods. (Highest biodiversity of terrestrial biomes)
Soil is very poor in nutrients because nutrients are “tied up” in vegetation

36. A tropical rain forest in Borneo
Fig a
Figure Terrestrial biomes
For the Discovery Video Trees, go to Animation and Video Files.
A tropical rain forest in Borneo

37. Desert
Precipitation is low and highly variable, generally less than 30 cm per year; deserts may be hot or cold
Desert plants are adapted for heat and desiccation tolerance, water storage, and reduced leaf surface area
Common desert animals include many kinds of snakes and lizards, scorpions, ants, beetles, migratory and resident birds, and seed-eating rodents; many are nocturnal

38. A desert in the southwestern United States
Fig b
Figure Terrestrial biomes
A desert in the southwestern
United States

39. Savanna (have not seen on ap)
Savanna precipitation and temperature are seasonal
Grasses and forbs make up most of the ground cover
Common inhabitants include insects and mammals such as wildebeests, zebras, lions, and hyenas
Chaparral (have not seen on ap)
Chaparral climate is highly seasonal, with cool and rainy winters and hot dry summers
The chaparral is dominated by shrubs, small trees, grasses, and herbs; many plants are adapted to fire and drought
Animals include amphibians, birds and other reptiles, insects, small mammals and browsing mammals

40. Fig c
Figure Terrestrial biomes
A savanna in Kenya

41. An area of chaparral in California Fig. 52-21d
Figure Terrestrial biomes
An area of chaparral
in California

42. Temperate Grassland (have not seen on ap)
Temperate grasslands are found on many continents (key word is temperate)
Winters are cold and dry, while summers are wet and hot
The dominant plants, grasses and forbs, are adapted to droughts and fire
Native mammals include large grazers and small burrowers

43. Sheyenne National Grassland in North Dakota
Fig e
Sheyenne National Grassland
in North Dakota
Figure Terrestrial biomes

44. Northern Coniferous Forest (also known as Taiga or Boreal Forest)
The northern coniferous forest, or taiga, extends across northern North America and Eurasia and is the largest terrestrial biome on Earth
Winters are cold and long while summers may be hot
The conical shape of conifers prevents too much snow from accumulating and breaking their branches
Animals include migratory and resident birds, and large mammals

45. Rocky Mountain National Park in Colorado
Fig f
Figure Terrestrial biomes
Rocky Mountain National Park
in Colorado

46. Temperate Broadleaf Forest (have not seen on ap)
Winters are cool, while summers are hot and humid; significant precipitation falls year round as rain and snow
A mature temperate broadleaf forest has vertical layers dominated by deciduous trees in the Northern Hemisphere and evergreen eucalyptus in Australia
Mammals, birds, and insects make use of all vertical layers in the forest
In the Northern Hemisphere, many mammals hibernate in the winter

47. National Park in North Carolina
Fig g
Great Smoky Mountains
National Park in North Carolina
Figure Terrestrial biomes

48. Tundra
Tundra covers expansive areas of the Arctic; alpine tundra exists on high mountaintops at all latitudes
Winters are long and cold while summers are relatively cool; precipitation varies
Permafrost, a permanently frozen layer of soil, prevents water infiltration
Vegetation is herbaceous (mosses, grasses, forbs, dwarf shrubs and trees, and lichen) and supports birds, grazers, and their predators

49. Denali National Park, Alaska, in autumn
Fig h
Figure Terrestrial biomes
Denali National Park, Alaska,
in autumn

50. Fig. 52-T1

51. Fig. 52-UN3

52. 100 Mean height (cm) 50 3,000 Altitude (m) 2,000 Sierra Nevada
Fig. 52-UN2
100
Mean height (cm) 50
3,000
Altitude (m)
2,000
Sierra Nevada
1,000
Great Basin
Plateau
Seed collection sites

53. You should now be able to:
Distinguish among the following types of ecology: organismal, population, community, ecosystem, and landscape
Explain how dispersal may contribute to a species’ distribution
Distinguish between the following pair of terms: biotic and abiotic factors
Explain how a body of water might affect regional climatic conditions
Define the following terms: photic zone, aphotic zone, benthic zone, abyssal zone,
List and describe the characteristics of the major aquatic biomes
List and describe the characteristics of the major terrestrial biomes
Compare the vertical layering of a forest and grassland