Ecosystems: What Are They and How Do They Work?

1
Ecosystems What Are They and How Do They Work?

• Chapter 3

2
Importance of Insects

• Pollination
• Pest control
• Important roles in biological community

Fig. 4-A, p. 64
3
Nature of Ecology

• What is ecology?
• Organisms
• Cells
• Species
• Microbes rule!

Fig. 3-2, p. 37
4
Populations, Communities, and Ecosystems

• Populations
• Genetic diversity
• Biological community
• Ecosystems
• Biosphere

5
Population of Monarch Butterflies
Fig. 4-3, p. 63
6
Genetic Diversity in One Snail Species
Fig. 4-3, p. 63
7
What Sustains Life on Earth?

• Troposphere
• Stratosphere
• Hydrosphere
• Lithosphere
• Biosphere

Fig. 3-2, p. 42
8
Earths Life-Support Systems

• One way flow of high-quality energy
• Cycling of matter
• Gravity

Fig. 3-6, p. 39
9
Flow of Solar Energy to and from the Earth

• Greenhouse gases
• Greenhouse effect

Fig. 3-3, p. 42
10
Flow of Solar Energy to and from the Earth
Fig. 3-3, p. 42
11
Why is the Earth so Favorable for Life?

• Liquid water
• Temperature
• Gravity
• Atmosphere

12
Ecosystem Components

• Biomes
• Aquatic life zones
• Freshwater life zones
• Ocean or marine life zones
• Abiotic and biotic components
• Range of tolerance
• Law of tolerance

13
Major Biomes
Average annual precipitation
100125 cm (4050 in.) 75100 cm (3040
in.) 5075 cm (2030 in.) 2550 cm (1020
in.) below 25 cm (010 in.)
4,600 m (15,000 ft.) 3,000 m (10,000 ft.) 1,500 m
(5,000 ft.)
Sierra Nevada Mountains
Great American Desert
Rocky Mountains
Great Plains
Mississippi River Valley
Appalachian Mountains
Coastal mountain ranges
Coniferous forest Desert Coniferous forest
Prairie grassland Deciduous forest
Coastal chaparral and scrub
Fig. 3-8, p. 41
14
Major Components of Freshwater Ecosystems
Sun
Producers (rooted plants)
Producers (phytoplankton)
Primary consumers (zooplankton)
Tertiary consumers (turtles)
Secondary consumers (fish)
Dissolved chemicals
Sediment
Decomposers (bacteria and fungi)
Fig. 3-9, p. 42
15
Major Components of a Field Ecosystem
Sun
Oxygen (O2)
Producer
Carbon dioxide (CO2)
Secondary consumer (fox)
Primary consumer (rabbit)
Producers
Falling leaves and twigs
Precipitation
Soil decomposers
Water
Soluble mineral nutrients
Fig. 3-10, p. 42
16
Range of Tolerance
Lower limit of tolerance
Upper limit of tolerance
Few organisms
Few organisms
No organisms
No organisms
Abundance of organisms
Population Size
Zone of intolerance
Zone of intolerance
Optimum range
Zone of physiological stress
Zone of physiological stress
Temperature
Low
High
Fig. 3-11, p. 43
17
Factors Limiting Population Growth

• Limiting factors
• Limiting factor principle
• Excess water or water shortages for terrestrial
  organisms
• Excess or lack of soil nutrients
• Dissolved oxygen for aquatic organisms
• Salinity for aquatic organisms

18
Major Biological Components of Ecosystems

• Producers (autotrophs)
• Photosynthesis
• Chemosynthesis
• Consumers (heterotrophs)

19
Consumers Feeding and Respiration

• Decomposers
• Omnivores
• Detritivores
• Aerobic respiration

20
Detritivores
Detritus feeders
Decomposers
Termite and carpenter ant work
Carpenter ant galleries
Bark beetle engraving
Long-horned beetle holes
Dry rot fungus
Wood reduced to powder
Mushroom
Time progression
Powder broken down by decomposers into plant
nutrients in soil
Fig. 3-8, p. 45
21
Main Structural Components of an Ecosystem
Abiotic chemicals (carbon dioxide, oxygen,
nitrogen, minerals)
Heat
Solar energy
Heat
Heat
Producers (plants)
Decomposers bacteria, fungi)
Consumers (herbivores, carnivores)
Heat
Heat
Fig. 3-9, p. 46
22
Biodiversity
Fig. 3-14, p. 45
23
Examples of Biodiversity
Fig. 3-15, p. 46
24
Food Chains and Food Webs

• Food chain
• Trophic level
• Food web

25
Model of a Food Chain
First Trophic Level
Second Trophic Level
Third Trophic Level
Fourth Trophic Level
Producers (plants)
Primary consumers (herbivores)
Secondary consumers (carnivores)
Tertiary consumers (top carnivores)
Heat
Heat
Heat
Solar energy
Heat
Heat
Heat
Heat
Detritivores decomposers and detritus feeders)
Heat
Fig. 3-10, p. 47
26
Food Web in the Antarctic
Humans
Sperm whale
Blue whale
Elephant seal
Killer whale
Crabeater seal
Leopard seal
Adélie penguins
Emperor penguin
Petrel
Fish
Squid
Carnivorous plankton
Herbivorous zooplankton
Krill
Phytoplankton
Fig. 3-11, p. 48
27
Energy Flow in an Ecosystem

• Biomass
• Ecological efficiency
• Pyramid of energy flow

28
Pyramid of Energy Flow
Heat
Heat
Decomposers
Tertiary consumers (human)
Heat
10 100 1,000 10,000 Usable
energy available at each tropic level (in
kilocalories)
Secondary consumers (perch)
Heat
Primary consumers (zooplankton)
Heat
Producers (phytoplankton)
Fig. 3-12, p. 49
29
Biomass Productivity

• Gross primary productivity (GPP)
• Net primary productivity (NPP)
• NPP and populations

30
Differences between GPP and NPP
Sun
Photosynthesis
Energy lost and unavailable to consumers
Respiration
Gross primary production
Net primary production (energy available
to consumers)
Growth and reproduction
Fig. 3-19, p. 49
31
Net Primary Productivity in Major Life Zones and
Ecosystems
Terrestrial Ecosystems
Swamps and marshes Tropical rain forest Temperate
forest Northern coniferous forest (taiga) Savanna
Agricultural land Woodland and shrubland Temperate
grassland Tundra (arctic and alpine) Desert
scrub Extreme desert Aquatic Ecosystems Estuaries
Lakes and streams Continental shelf Open ocean
800 1,600 2,400 3,200 4,000 4,800 5,600
6,400 7,200 8,000 8,800 9,600
Average net primary productivity (kcal/m2/yr)
Fig. 3-13 p. 49
32
Soils

• Origins of soils
• Soil horizons O, A, B, and C
• Soil profiles
• Infiltration and leaching

33
Soil Formation and Horizons
Woodsorrel
Lords and ladies
Oak tree
Dog violet
Organic debris builds up
Earthworm
Grasses and small shrubs
Rock fragments
Millipede
Moss and lichen
Mole
Fern
Honey fungus
O horizon Leaf litter
A horizon Topsoil
Bedrock
B horizon Subsoil
Immature soil
Regolith
Young soil
Pseudoscorpion
C horizon Parent material
Mite
Nematode
Actinomycetes
Root system
Red earth mite
Springtail
Fungus
Fig.10-A, p. 209
Mature soil
Bacteria
34
Soil Profiles from Different Ecosystems
Fig. 3-22, p. 52
35
Soil Profiles from Different Ecosystems
Mosaic of closely packed pebbles, boulders
Alkaline, dark, and rich in humus
Weak humus- mineral mixture
Dry, brown to reddish-brown, with variable
accumulations of clay, calcium carbonate,
and soluble salts
Clay, calcium compounds
Desert Soil (hot, dry climate)
Grassland Soil (semiarid climate)
Fig. 3-22a, p. 52
36
Soil Profiles from Different Ecosystems
Forest litter leaf mold
Acid litter and humus
Acidic light- colored humus
Humus-mineral mixture
Light-colored and acidic
Light, grayish- brown, silt loam
Iron and aluminum compounds mixed with clay
Humus and iron and aluminum compounds
Dark brown Firm clay
Tropical Rain Forest Soil (humid, tropical
climate)
Deciduous Forest Soil (humid, mild climate)
Coniferous Forest Soil (humid, cold climate)
Fig. 3-22b, p. 52
37
pH

• Acidity or alkalinity of water or water-bearing
  samples
• Scale 0-14
• Acidic pH 0-6.9
• Neutral pH 7.0
• Alkaline (basic) pH 7.1-14

38
The pH Scale
Fig. 3-23, p. 192
39
Matter Cycling in Ecosystems Biogeochemical
Cycles

• Nutrient (biogeochemical) cycles
• Hydrologic (water) cycle
• Carbon cycle
• Nitrogen cycle
• Phosphorus cycle
• Sulfur cycle

40
Simplified Hydrologic (Water) Cycle
Condensation
Rain clouds
Transpiration
Evaporation
Precipitation to land
Transpiration from plants
Precipitation
Precipitation
Evaporation From land
Evaporation From ocean
Surface runoff (rapid)
Rapid
Precipitationto ocean
Surface runoff (rapid)
Infiltration and percolation
Groundwater movement (slow)
Ocean storage
Fig. 3-14, p. 51
41
Human Intervention in the Hydrologic Cycle

• Large withdraw of surface and ground waters
• Clearing vegetation
• Pollution

42
The Carbon Cycle (Marine)
Diffusion between atmosphere and ocean
Combustion of fossil fuels
Carbon dioxide dissolved in ocean water
aerobic respiration
photosynthesis
Marine food webs Producers, consumers, decomposers
, detritivores
incorporation into sediments
uplifting over geologic time
death, sedimentation
sedimentation
Marine sediments, including formations with
fossil fuels
Fig. 3-15 p. 53
43
The Carbon Cycle (Terrestrial)
Atmosphere (most carbon is in carbon dioxide)
Combustion of fossil fuels
volcanic action
combustion of wood (for clearing land or fuel)
aerobic respiration
photosynthesis
Terrestrial rocks
deforestaion
Land food webs Producers, consumers, decomposers,
detritivores
weathering
Soil water (dissolved carbon)
Peat, fossil fuels
death, burial, compaction over geologic time
leaching, runoff
Fig. 3-15, p. 53
44
Human Interference in the Global Carbon Cycle
Fig. 3-26, p. 56
45
The Nitrogen Cycle
Fig. 3-16 p. 54
46
Human Interference in the Global Nitrogen Cycle
Nitrogen fixation by natural processes
processes
human
by
fixation
Nitrogen
Fig. 3-28, p. 58
47
The Phosphorus Cycle
mining
Fertilizer
Guano
excretion
agriculture
uptake by autotrophs
uptake by autotrophs
Land Food Webs
Dissolved in Soil Water, Lakes, Rivers
leaching, runoff
Dissolved in Ocean Water
Marine Food Webs
death, decomposition
weathering
weathering
settling out
sedimentation
uplifting over geologic time
Rocks
Marine Sediments
Fig. 3-17, p. 55
48
The Sulfur Cycle
Water
Ammonia
Sulfur trioxide
Sulfuric acid
Acidic fog and precipitation
Ammonium sulfate
Oxygen
Hydrogen sulfide
Sulfur dioxide
Plants
Volcano
Dimethyl sulfide
Animals
Industries
Ocean
Sulfate salts
Metallic Sulfide deposits
Decaying matter
Sulfur
Hydrogen sulfide
Fig. 3-18, p. 56
49
How Do Ecologists Learn about Ecosystems?

• Field research
• Remote sensing
• Geographic information system (GIS)
• Laboratory research
• Systems analysis

50
Geographic Information System (GIS)
Critical nesting site locations
USDA Forest Service
USDA Forest Service
Private owner 1
Private owner 2
Topography
Forest
Habitat type
Wetland Lake
Grassland
Real world
Fig. 3-31, p. 61
51
Stages of Systems Analysis
Construct mathematical model describing
interactions among variables
Run the model on a computer, with values entered
for different variables
Evaluate best ways to achieve objectives
Stepped Art
Fig. 3-32, p. 61
52
Importance of Baseline Ecological Data

• To understand nature, current conditions must be
  known
• Baseline data are lacking
• Long-term sustainability