Title: Ecosystems: What Are They and How Do They Work?
1Ecosystems What Are They and How Do They Work?
23-1 What Is Ecology?
- Concept 3-1 Ecology is the study of how
organisms interact with one another and with
their physical environment of matter and energy.
33-1 What Is Ecology?
- Ecology is a study of connections in nature.
- How organisms interact with one another and with
their nonliving environment.
4Species Make Up the Encyclopedia of Life
- Organisms individual forms of life
- Classified into species based on certain
characteristics - Species a set of individuals that can mate and
produce viable, fertile offspring
- 1.75 Million species identified
- Up to 1014 million species not yet identified??
- Insects make up most of the known species
5Science Focus Have You Thanked the Insects
Today?
- Many times we classify insects as pests
- Compete with us for food
- Spread human diseases
- Bite or sting us
- Can be a nuisance
- However, they are VERY beneficial
- Pollinators
- Eat other insects
- Loosen and renew soil
- Estimated 57 billion/yr in ecological services
6Species Make Up the Encyclopedia of Life
- A population is a group of interacting
individuals of the same species occupying a
specific area. - The space an individual or population normally
occupies is its habitat.
7Species Make Up the Encyclopedia of Life
- Genetic diversity
- In most natural populations individuals vary
slightly in their genetic makeup. - These genetic diversity is crucial to the
survival of the population.
8Levels of Organization of Matter in Nature
- Populations of different species living and
interacting in an area form a community. - A community interacting with its physical
environment of matter and energy is an ecosystem. - The biosphere is where all of the Earths life is
found - A global ecosystem
93-2 What Keeps Us and Other Organisms Alive?
- Concept 3-2 Life is sustained by the flow of
energy from the sun through the biosphere, the
cycling of nutrients within the biosphere, and
gravity.
10Natural Capital General Structure of the Earth
- The biosphere consists of several physical layers
that contain - Air
- Water
- Soil
- Minerals
- Life
11The Earths Life-Support System Has Four Major
Components
- Biosphere All of the life on the planet
- Atmosphere Membrane of air around the planet.
- Troposphere lowest layer - most gas of any
layer - where weather occurs
- Stratosphere contains ozone to filter out most
of the suns harmful UV radiation. - Hydrosphere All the earths water liquid, ice,
water vapor - Geosphere The earths crust and upper mantle
- Lithosphere hard outer crust
- Asthenosphere molten interior
12Three Factors Sustain Life on Earth
- One-way flow of energy beginning with the sun
- Follows the laws of thermodynamics
- Most is lost as heat
- Cycling of matter or nutrients
- Nutrients exist in a fixed amount
- Follows the law of conservation of matter
- Gravity
-
13Flow of Energy to and from the Earth
- Solar energy flowing through the biosphere warms
the atmosphere, evaporates and recycles water,
generates winds and supports plant growth.
- Natural greenhouse effect natural process that
keeps the Earth warmer than it would otherwise be
14Life Exists on Land and in Water
- Life exists on land systems called biomes and in
freshwater and ocean aquatic life zones.
153-3 What Are the Major Components of an
Ecosystem?
- Concept 3-3A Ecosystems contain living (biotic)
and nonliving (abiotic) components. - Concept 3-3B Some organisms produce the
nutrients they need, others get their nutrients
by consuming other organisms, and some recycle
nutrients back to producers by decomposing the
wastes and remains of organisms.
16Ecosystems Have Living and Nonliving Components
- Ecosystems consist of living (biotic) and
nonliving (abiotic) components.
- Biotic or Abiotic?
- Plants
- Water
- Animals
- Temperature
- Rocks/Minerals
- Bacteria
- Solar Energy
- Landforms
- Soil
17Several Abiotic Factors Can Limit Population
Growth
- Populations have a range of tolerance to
variations in their physical and chemical
environments.
18Several Abiotic Factors Can Limit Population
Growth
- Availability of matter and energy resources can
limit the number of organisms in a population. - Limiting factor principle
- Too much or too little of any abiotic factor can
limit or prevent growth of a population, even if
all other factors are at or near the optimal
range of tolerance
19Several Abiotic Factors Can Limit Population
Growth
- The physical conditions of the environment can
limit the distribution (range) of a species.
20Producers and Consumers Are the Living Components
of Ecosystems
- Producers, or autotrophs, make their own food
from nutrients/energy obtained from the
environment - Most producers capture sunlight to produce
carbohydrates by photosynthesis
You must memorize this equation if you havent
already. It will come up throughout the year.
21Photosynthesis
- Chlorophyll molecules in the chloroplasts of
plant cells absorb solar energy. - This initiates a complex series of chemical
reactions in which carbon dioxide and water are
converted to sugars and oxygen.
22Producers and Consumers Are the Living Components
of Ecosystems
- Some organisms can obtain energy from inorganic
compounds in their environment WITHOUT sunlight
through a process called chemosynthesis. - Deep ocean bacteria draw energy from hydrothermal
vents and produce carbohydrates from hydrogen
sulfide (H2S) gas.
23Producers and Consumers Are the Living Components
of Ecosystems
- Consumers, or heterotroph, cannot produce their
own food and, therefore, must obtain their
nutrients by feeding on other organisms. - Herbivores
- Primary consumers that eat producers
- Carnivores
- Secondary consumers eat primary consumers
- Third- and higher-level consumers carnivores
that eat carnivores - Omnivores
- Feed on both plant and animals
24Producers and Consumers Are the Living Components
of Ecosystems
- Detritivores Insects or other scavengers that
feed on wastes or dead bodies (detritus)
physically break down - Decomposers Bacteria and/or fungi that use
enzymes to recycle nutrients in ecosystems
chemically break down
25Producers and Consumers Are the Living Components
of Ecosystems
- Organisms break down carbohydrates and other
organic compounds in their cells to obtain the
energy they need. - This is usually done through
aerobic respiration. - Aerobic means with oxygen
You must memorize this equation if you havent
already. It will come up throughout the year.
26Producers and Consumers Are the Living Components
of Ecosystems
- Some decomposers get energy by breaking down
glucose (or other organic compounds) WITHOUT
oxygen through a process called anaerobic
respiration, or fermentation - Anaerobic means without oxygen
- The end products vary based
on the chemical reaction - Methane gas
- Ethyl alcohol
- Acetic acid
- Hydrogen sulfide
27Energy Flow and Nutrient Cycling Sustain
Ecosystems and the Biosphere
- An ecosystem is sustained by a combination of a
one-way flow of energy and the cycling of key
nutrients.
28Science Focus Many of the Worlds Most
Important Species Are Invisible to Us
- Multitudes of tiny microbes such as bacteria,
protozoa, fungi, and yeast help keep us alive. - Harmful microbes are the minority
- Soil bacteria (nitrogen fixing bacteria) convert
nitrogen gas to a usable form for plants - They help produce foods bread, cheese, yogurt,
beer, wine - Make up 90 of all living mass on Earth
- Help purify water, provide oxygen, breakdown
waste - Live beneficially in your body (intestines, nose)
293-4 What Happens to Energy in an Ecosystem?
- Concept 3-4A Energy flows through ecosystems in
food chains and webs. - Concept 3-4B As energy flows through ecosystems
in food chains and webs, the amount of chemical
energy available to organisms at each succeeding
feeding level decreases.
30Energy Flows Through Ecosystems in Food Chains
and Food Webs
- Food chains and webs show how eaters, the eaten,
and the decomposed are connected to one another
in an ecosystem.
- The arrows point in the direction of the energy
flow.
31Energy Flows Through Ecosystems in Food Chains
and Food Webs
- A food web shows the connections of all organisms
within an ecosystem.
32Usable Energy Decreases with Each Link in a Food
Chain or Web
- Biomass the dry weight of all organic matter
contained in an organism(s). - Chemical energy in biomass is transferred from
one trophic level to another.
33Pyramid of Energy Flow
- Ecological efficiency percentage of useable
energy transferred as biomass from one trophic
level to the next. - Typically, only 10 efficient (90 lost as heat)
34Usable Energy Decreases with Each Link in a Food
Chain or Web
- Food chains rarely have more than 4 steps or 3
trophic levels. Why?
35Usable Energy Decreases with Each Link in a Food
Chain or Web
- In accordance with the 2nd law of thermodynamics,
there is a decrease in the amount of energy
available to each succeeding organism in a food
chain or web.
- Cellular respiration - the breakdown of glucose
to release energy is only 38 efficient - Energy is lost as heat
- Energy is also used for growth, reproduction,
movement
- Ultimately, only about 10 of the original energy
is available for the next trophic level (90 lost
as heat)
36Some Ecosystems Produce Plant Matter Faster Than
Others Do
- Gross primary production (GPP)
- Rate at which an ecosystems producers convert
solar energy into chemical energy
(photosynthesis) as biomass.
37Some Ecosystems Produce Plant Matter Faster Than
Others Do
- Net Primary Production (NPP)
- Rate at which producers use photosynthesis to
store energy minus the rate at which they use
some of this energy through respiration (R).
38Estimated Annual Average NPP in Major Life Zones
and Ecosystems
- What are natures most productive/least
productive systems?
39Info from notes handout
40Info from notes handout
- Pyramid of Numbers
- Pyramid of Biomass
- Pyramid of Energy
413-5 What Happens to Matter in an Ecosystem?
- Concept 3-5 Matter, in the form of nutrients,
cycles within and among ecosystems and the
biosphere, and human activities are altering
these chemical cycles.
42Nutrients Cycle in the Biosphere
- Biogeochemical Cycles recycle nutrients through
the earths air, land, water, and living
organisms. - Nutrients are the elements and compounds that
organisms need to live, grow, and reproduce. - Biogeochemical cycles move these substances
through air, water, soil, rock and living
organisms. - Connect past, present , and future forms of life
43The Water Cycle
44The Water Cycle
45Effects of Human Activities on Water Cycle
- Humans alter the water cycle by
- Withdrawal of large amounts of freshwater at
rates faster than nature can replace it - Clearing vegetation and eroding soils.
- Increased flooding when wetlands are drained
- Polluting surface and underground water.
- Contributing to climate change.
- Increases melting, evaporation, precipitation,
etc.
46The Carbon Cycle
47The Carbon Cycle
48Effects of Human Activities on Carbon Cycle
- Humans alter the carbon cycle by adding excess
CO2 to the atmosphere through - Burning fossil fuels
- Clearing/burning vegetation faster than it is
replaced
49The Nitrogen Cycle
50The Nitrogen Cycle
51Nitrogen Cycles through the Biosphere Bacteria
in Action
- Nitrogen fixation converting atmospheric N2
into ammonia (NH3) or ammonium (NH4) that can be
used by plants - Lightning ammonia falls to the ground with the
rain - Nitrogen-fixing bacteria
- Nitrification Nitrifying bacteria convert
ammonium (NH4) to nitrates (NO3) and/or nitrites
(NO2) - Denitrification Denitrifying bacteria convert
ammonia, nitrates, or nitrites back into
atmospheric N2. - Ammonification Decomposers convert ditritus
into ammonia or ammonium.
52Nitrogen Fixation A Closer Look
53Effects of Human Activities on the Nitrogen Cycle
- Humans alter the nitrogen cycle by
- Adding gases that contribute to acid rain
- NO and N2O
- Contaminating bodies of water with excess
nitrates from inorganic fertilizers - Humans fix more nitrogen than all natural sources
combined - Adding nitrogen to the troposphere through
deforestation - Remove nitrogen from topsoil
54The Phosphorous Cycle
55The Phosphorous Cycle
56Effects of Human Activities on the Phosphorous
Cycle
- Cycles through water, the earths crust, and
living organisms (NOT the atmosphere like the
others) - May be limiting factor for plant growth
- Humans alter the phosphorus cycle by
- We remove large amounts of phosphate from the
earth to make fertilizer. - We reduce phosphorous in tropical soils by
clearing forests. - We add excess phosphates to aquatic systems from
runoff of animal wastes and fertilizers.
57The Sulfur Cycle
58The Sulfur Cycle
59Effects of Human Activities on the Sulfur Cycle
- Sulfur found in organisms, ocean sediments, soil,
rocks, and fossil fuels. - Sulfur dioxide (SO2) in the atmosphere
- Humans alter the sulfur cycle by adding sulfur
dioxide to the atmosphere through - Burning sulfur-containing coal and oil
- Refining sulfur-containing petroleum
- Smelting sulfur-containing metallic mineral ores
- These can all lead to acid rain
- Sulfuric acid (H2SO4) when SO4 mixes with H2O