Ecology

ECOLOGY•The study of living organisms and their interaction with the nonliving environment

Historical Background•Ecology

•Eco = “house”

ology = “study of”

•BIOTIC ABIOTIC

Realms of Ecology•Organisms

•Populations

•Communities

•Ecosystems

•Biome

•Biosphere

What Ecologists Study

•Concerned with levels of organization ABOVE population

The Biosphere

• The portion of the earth where living organisms exist– If the earth were an apple, the

biosphere would be no thicker than the skin

Atmosphere

• The troposphere– Surface to 17 km (11 miles) up– Contains most of the oxygen and nitrogen

• The stratosphere– 17 to 48 km up– Contains most of the O3

– Screens out all UV-C– Screens out most UV-B– Screens out some UV-A

Hydrosphere

• All the water on the earth– Liquid water• Surface• underground

– Ice• Polar ice• Icebergs• Ice in frozen soil

–Water vapor in the atmosphere

Lithosphere

• Crust and upper mantle– Contains all fossil fuels– Contains all usable minerals– Contains all nutrients for plant life

What Sustains Life on Earth?

Life on Earth depends on three interconnecting factors

• One way flow of energy– From the sun– Through plants and animals

• Cycling of matter– All nutrients must be recycled repeatedly

• Gravity– Allows the planet to hold its atmosphere– Causes downward movement of chemicals in

cycles

How the Sun Helps Sustain Life

• Lights and warms the planet

• Supports photosynthesis

• Powers matter cycling

• Drives climate and weather systems


• Lights and warms the planet

– Earth receives about 1/1,000,000,000 of the suns energy output

– 34% reflected back into space

– The remaining 66%• Warms the troposphere and land• Evaporates water• Generates winds


• Supports photosynthesis– Creates carbohydrates – Creates oxygen– Speeds decomposition


• Powers matter cycling– Carbon cycle– Nitrogen cycle–Water cycle– Oxygen cycle– Phosphorous cycle


• Drives climate and weather systems– Distributes heat– Distributes fresh water

Natural Greenhouse Effect

• Most solar radiation is degraded into heat

• Greenhouse gasses keep the heat around the planet– Water vapor– Carbon dioxide– Methane– Nitrous oxide– ozone

• Without the greenhouse effect, Earth would be as cold as Mars

Ecosystem Concepts

• Biomes – large regions of land characterized by a distinct climate and specific animal and especially plant species– Forests– Desserts– Grasslands– Jungles

Ecosystem Concepts

• Biomes - consist of two components– abiotic • Water• Air• Solar energy• nutrients

– Biotic (biota)• Animals• Plants• microorganisms

Ecosystem Concepts

• Ecotones – biomes do not have clear-cut edges. They blend into one another

– Ecotones contain a mixture of organisms from each biome and frequently species found nowhere else

– Ecotones are more biologically diverse than either of the bordering biomes

Deciduous Forest/River Ecotone

Aquatic/Marine life Zones

• Fresh water life zones– Lakes & ponds– Streams & rivers

• Marine life zones– Estuaries– Coastlines– Coral reefs– Deep oceans

Abiotic Limitations

• Abiotic

• Water – how much or how little

• Solar energy – shade or sun

• Nutrients – rich or poor

Range of Tolerance

• There is an optimum range of each abiotic component of a biome for each species

• Individuals in a population may have slightly different tolerances

Law of Tolerance

The levels, abundance and distribution of a species in an ecosystem are determined by whether the levels of one or more physical or chemical factors fall within the ranger tolerated by that species.

Translation: Don’t expect to find polar bears in Tahiti

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 optimum range of tolerance.

Translation: If the restaurant serves really spicy food, don’t look for Anglos


• Too much of a particular abiotic factor can also be a limiting factor

• Limiting factors can change


• Aquatic or marine life zones also have limiting factors

– Sunlight– Dissolved oxygen– Nutrient availability– Salinity

Living Components of the Biome

• Metabolism – all living creatures capture and transform matter and energy from their environment to supply their needs for survival, growth and reproduction

Living Components of the Biome

All living things are divided into two groups

• Producers – make their own food from components obtained from the environment

• Consumers – obtain nutrients and energy by consuming other organisms or their remains

ProducersAutotrophs

Most producers capture sunlight and abiotic nutrients to produce carbohydrates (such as glucose (C6H12O6) in a process called Photosynthesis

Photosynthesis

Carbon dioxide + water + solar energy glucose + oxygen

CO2 + 6 H2O + solar energy C6H12O6+ 6 O2

Chemosynthesis

Hydrogen sulfide + carbon dioxide + geothermal heat nutrients

H2S + CO2 + geothermal heat nutrients

ConsumersHeterotrophs

Obtain their energy and nutrients by consuming other organisms or their remains

ConsumersHeterotrophs

All these organisms consume living prey• Herbivores – (primary consumers) feed

directly on producers• Carnivores – (meat eaters) feed on other

consumers– Secondary consumers – feed only on primary

consumers– Tertiary consumers – (higher level consumers)

feed on other carnivores

• Omnivores – feed on both plants and animals

HerbivoresPrimary Consumers

CarnivoresSecondary Consumers

Heterotrophssome feed on the dead or dying

• Scavengers – feed on dead animal carcasses

• Detritivores – feed on waste, parts of carcasses or cast off parts

• Detritus feeders – feed on partially decomposed organic matter

• Decomposers – (mostly bacteria and fungi) break down dead organic materials to simpler inorganic compounds

Aerobic Respiration and Photosynthesis

• Photosynthesis Energy + Carbon Dioxide + water glucose +

oxygensunlight + CO2 + H2O C6H12O6 + O2

• Aerobic Respiration glucose + oxygen carbon dioxide + water +

Energy C6H12O6 + O2 CO2 + H2O + Energy

Energy Cycling

• Solar energy is collected by plants (producers)

– Most of the energy from the sun is lost as heat

• Primary consumers (herbivores) eat the plants– Most of the energy is lost as

heat

• Secondary consumers (carnivores) eat the primary consumers– Most of the energy is lost as

heat

Energy Cycling

• Tertiary consumers eat the secondary consumers– Most of the energy is lost as

heat

• Detritivores consume the dead and dying– Most of the energy is lost as

heat

Energy Cycling

As you pass up the energy pyramid, the number of organisms decreases.

At each step in the pyramid, ~90% of the energy is lost as heat

Food Chains

• Simplified constructs used to show energy flow in the ecosystem

• Food chains do not exist in nature

Food Webs

• Food webs are more realistic representations of nature

• Organisms rarely feed at only one trophic level

Available Energy

• How many trophic levels are present depends on how much energy is available in an ecosystem– There are rarely more than four or five

trophic levels in an ecosystem• The amount of energy an ecosystem

produces is called the Net Primary Productivity

• Measured in kcal/m2/yr or g/m2/yr

Net Primary ProductivityEquals

Rate at which producers store chemical energy as biomass

Minus

(produced by photosynthesis)

Rate at which producers use chemical energy stored as biomass

(through aerobic respiration)

Net Primary Productivity

Different EcosystemsProduce Different Biomass

Most Productive

• Estuaries• Swamps/marshes• Tropical rainforests

Least Productive

• Open ocean• Tundra• Desert

Human Biomass Usage

• Humans have taken over, disturbed or degraded ~73% of the earths’ land surface

• Humans use, waste or destroy ~27% of the earths’ total potential net primary productivity and ~40% of the total potential net primary productivity of terrestrial ecosystems

Matter Cycling

• Energy is an open system– Energy enters the system as sunlight

(low entropy) and is degraded and dispersed (high entropy) as organisms use it

• Matter is a closed system– All matter is recycled in one of three

ways

Matter Cycles

There are three major types of nutrient recycling

1. Hydraulic cycle (ex. Water cycle)2. Atmospheric cycle (ex. Carbon

cycle)3. Sedimentary cycle ( ex.

Phosphorous)

Hydraulic Cycle

• Water evaporates and cycles through the biosphere– Local– Regional– global

Atmospheric Cycle

• A large portion of the nutrient exist in the atmosphere and cycle rapidly through soil, organisms and back to the atmosphere– Local– Regional– Global

Sedimentary Cycle

Earths’ crust is the main storehouse. Elements move from the land to the seabed then back to land through geological uplift and volcanic action

– global

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