Basic Ecology

Four Levels of Investigation

1. Organism2. Population– An interbreeding group belonging to the same

species

3. Community– All the populations of different species in an area

4. Ecosystem– The community and all non living factors of an

area

Ecosystem examples:

Ponds

Pastures

Coral reefs

Woodlots

Aquariums

EcosystemsEcosystems: involve exchange of matter and energy : involve exchange of matter and energy between living and nonliving elements in a manner that between living and nonliving elements in a manner that sustains lifesustains life

- includes plants, animals, air, soil, and water- includes plants, animals, air, soil, and water

Living part of the ecosystem: biotic community – plants, animals, insects, etc.

Nonliving part: abiotic (physical environment) – temperature, light, substrates, altitude, etc.

- biotic and abiotic exchange energy and material

Ecosystems consist of several communities

ex.: wetland communities

- great blue herons, egrets, ducks, geese, etc. = bird community

- dragonflies, mosquitoes, damselflies, spiders, etc. = insect community

- cottonmouth, garter snake, water snake, copperhead, etc. = snake community

The Macrocosm and Microcosm

• Cosmos – Everything that exists anywhere

• Macro – Large

• Micro – Small

• Macrocosm – The universe without

• Microcosm – The universe within

Primary Abiotic Factors

1. Solar Energy

2. Water

3. Temperature

4. Wind

The Atmosphere

The Origins of the Atmosphere

• Molten metals solidify within the frost line of the early solar system

• They become planetary seeds, and continue to grow as gravitational attraction brings them together

• As they approach planetary size the force of gravity causes a density distribution, with denser materials sinking and lighter ones rising

• Volcanic activity begins to spew trapped gasses into the air– H2O, CO2, CO, H2

• Earth is only massive enough to keep heavier gasses, H2 and He escape into space

• Oxygen is never released in this manner, and had to arrive through biological processing

Atmospheric Composition

Parts of the Atmosphere

Atmospheric Purpose

• It creates pressure which allows water to exist in liquid form

• It absorbs and scatter light making daytime skies bright• Absorption allows them to protect from dangerous

radiation• They cause wind and weather patterns• Interactions between atmospheric gasses and the solar

wind can create a protective magneto sphere around planets with a strong magnetic field

• Greenhouse gasses cause planetary temperatures to be warmer than they normally would be (H2O, CO2, CH4)

Greenhouse Gasses

Climate

•Curvature of the earth induces temperature variation•Temperature patterns induce wind•Evaporation and condensation patterns cause rainfall

Wind Induction

Water

The Origins of Terrestrial Oceans

• H2O was emitted by early volcanic activity.

• The major abundance of water on earth is still a mystery.

• Scientists speculate large amounts of water were brought to earth after it cooled by comets from the Kuiper Belt and Oort Cloud.

Water Ecosystems

1. Estuary: A freshwater stream or river merging with an ocean

2. Wetland: Inbetween an aquatic and terrestrial region where soil is saturated with water permanently or periodically

3. Intertidal zone: A wetland at the edge of an estuary or ocean which is sequentially covered by the tides

4. Pelagic Zone: Open ocean

Pelagic Regions

• Photic Zone: Oceanic region where light penetrates

• Aphotic Zone: Oceanic region where light does not penetrate sufficiently for photosynthesis

• Benthic Zone: The ocean floor

Primary Ecosystems

Biomes – worldwide grouping of similar communities, commonly described by dominant vegetation

Temperate GrasslandTemperate Grassland::

- Big bluestem, Little bluestem, Grama grass- Big bluestem, Little bluestem, Grama grass

- prairie chicken, western meadowlark, prairie - prairie chicken, western meadowlark, prairie dog, coyotedog, coyote

Temperate Deciduous ForestTemperate Deciduous Forest::

- Oaks, Maples- Oaks, Maples

- ruffed grouse, black-capped chickadee, blue jay, - ruffed grouse, black-capped chickadee, blue jay, white-tailed deer, fox squirrel, white-footed mousewhite-tailed deer, fox squirrel, white-footed mouse

DesertDesert::

- Sagebrush, Creosote bush, Cacti- Sagebrush, Creosote bush, Cacti

- sage grouse, burrowing owl, roadrunner, desert - sage grouse, burrowing owl, roadrunner, desert bighorn sheep, desert jackrabbitbighorn sheep, desert jackrabbit

TundraTundra::

- Sedges, Lichens, Cranberries- Sedges, Lichens, Cranberries

- snowy owl, golden plover, caribou, musk ox, brown - snowy owl, golden plover, caribou, musk ox, brown lemminglemming

Boreal ForestBoreal Forest::

- Spruce, Firs- Spruce, Firs

- gray jay, moose, lynx, snowshoe hare- gray jay, moose, lynx, snowshoe hare

Mediterranean Scrub Forest Mediterranean Scrub Forest ::

- Coffee-berry, Scrub oaks (fire-resistant)- Coffee-berry, Scrub oaks (fire-resistant)

- California quail, anna’s hummingbird, mule - California quail, anna’s hummingbird, mule deer, bobcat, brush rabbitdeer, bobcat, brush rabbit

Density and Dispersion Patterns

Dispersion Patterns

1. Clumped: Often results from unequal distributions of resources

2. Uniform: Often results from interactions between individuals of a population

3. Random: Quite rare. Occurs in the tropics.

Idealized Growth Models

Exponential Growth: G = rN

• G: Growth Rate

• r: Intrinsic rate of increase – An organism’s maximum capacity to reproduce. It can be estimated by subtracting the death rate from the birth rate.

• N: Population size

Population Limiting Factors

• K = Carrying Capacity: the maximum population size that an environment can support

What causes non-ideality?

• Declining birth rates

• Rising death rates

• Competition for limited resources

Boom and Bust Cycles

The Lynx and the Hare

Thermodynamics

History• The study of energy• Arose from the need to

increase the efficiency of steam engines

• Fluidic theory of heat disproved by Boyle

• 1824 Carnot publishes, “Reflections on the Motive Power of Fire.”

• The term, Thermodynamics, coined in 1849 by William Thomson (the Lord Kelvin).

Sadi Carnot

The Laws

1. Conservation of Energy – The change in the internal energy of a closed thermodynamic system is equal to the sum of the amount of heat energy supplied to the system and the work done on the system

2. Entropy – The total entropy of any isolated thermodynamic system tends to increase over time, approaching a maximum value.

3. Absolute Zero Temperature – As a system asymptotically approaches absolute zero all processes virtually cease and the entropy of the system goes to a minimum value.

The Laws - simplified

1. Conservation of Energy – The stuff is always there: you can’t get stuff from nothing, and stuff can’t disappear.

2. Entropy – The universe is lazy: stuff always take the path of least resistance. Entropy is a measurement of the chaos of the stuff.

3. Absolute Zero – Heat is actually movement of the stuff. If stuff is completely cold, it’s not moving at all.

Implications

• Disorder is Natural• Order is unnatural – specified

complexity is extremely rare.• Many processes are

irreversible– Can’t burn something twice– Eggs shatter, but they don’t

reassemble

• The universe is running down• Processes are always losing

energy

Dealing with Entopy

• Entropy is one of the most important scientific understandings of the behavior of matter.

• It has serious implications in philosophy as well.– Entropy makes rivers crooked– People do what is easiest to do

• Ancient people described this as the law of disintegration or decay. It was often represented by a serpent eating its tail.– Ezekiel’s valley of dry bones– Mummification is a defense

against it– Gold wasso admired for its

resistance to decay

Wisdom Schools and Entropy

• The Gods and the Fates

• Greek Tragedy – Man can’t win because he doesn’t know what’s coming.

Their Solution

1. No day is like any other; you can’t know the details of tomorrow.

2. Despite that, there is a pattern: Everything moves.3. Does it move in every way? No: everything is going

down.4. Since everything is going down, why didn’t

everything end a long time ago?5. Something is working the other way.– The sun goes down each year, but it comes back.

6. Though we can’t know the specifics of tomorrow, we can learn its patterns.

How Modern Science Uses Entropy

• We use equations to model the future.– If we can describe the trajectory of a cannon ball with an equation, we know its

future in that case.– The more repeatable the results, the more confident we are in our model.

• We understand that we have to put thought directed work into matter to order it for our purposes.– Example: We don’t wait around for a football stadium to organize itself, we

cause it to happen by putting work into the environment. – Example: Even though there is a chance that dust will fall on a table in the attic

in a perfect checkerboard pattern, we know it won’t. • Many times we don’t know the specifics of one particular thing, but we

know it for a group of them very well: statistics.– Example: the behavior of a fan at a football game as opposed to the entire

stadium.– Example: radioactive decay - the behavior of one atom as opposed to billions

of them in an object.– Implication: Stereotypes exist because they are mostly correct.

Energy Flow

The Origin of Energy

• All energy ultimately comes from mass

• E = mc2

• The Big Bang• As far as we are concerned,

from an ecological standpoint, almost all energy important to life comes from the sun.

• A small portion comes from deep oceanic thermal vents.

The Direction of Energy

• Energy is not recycled in ecosystems.• It must be imported from the sun.• Implication of the 2nd Law:–When energy is converted some is always lost as

heat. – Recall, this also means, ultimately, that the

universe is running down.– Ecosystems have limits placed on them due to loss

of energy.

Purpose of Energy in Organisms

• Entropy (ie chaos) is always breaking organisms down.

• The only way to counteract this trend is with energy applied in very specific ways.

• Organisms use energy in several ways:– builds cells, tissues, and organs (growth)

– thermoregulation

– digestion

– muscle activity

Trophic Structures•Sacrifice: The Law of Life•Trophic – Of, or relating to nutrition.•Everywhere along this chain energy is lost.

Plants are Producers – First trophic level

Photosynthesis starts the energy flow

Energy assimilated in photosynthesis = Gross Primary Productivity (GPP)

Plants use energy for maintenance needs

The leftover energy is stored as organic matter in green plants = Net Primary Productivity (NPP)

Primary consumers – Second trophic level

Herbivores (ex.: mouse, grasshopper, caterpillar, deer)

- eat plants and obtain NPP energy - some energy is used for maintenance, growth, or reproduction

- some energy is passed out of the body as waste

- some is lost as heat

Secondary consumers – Third trophic level

Carnivores and omnivores; predators (ex.: snake, frog, coyote, etc.)

- eat primary consumers

- energy is used for maintenance, growth, or reproduction

-some energy is passed out of the body as waste

- some energy is lost as heat

Tertiary consumers – Fourth trophic levelCarnivores; top predator (ex.: hawk, wolf, bear, etc.)

- eat secondary consumers

- energy is used for maintenance, growth, or reproduction

- some energy is passed out of the body as waste

- energy lost as heat

Decomposers – fungi and bacteria

- break down organic molecules from the ecosystem to obtain energy

- some is lost as heat

Limits• Between each level energy is lost• This puts limits on the possible levels an ecosystem can have• Consuming meat is simply less efficient than consuming plants

Matter Cycling

The Origins of Matter

• The first Law informs us that matter and energy are related: we may think of matter as frozen energy.

• The most prevalent elements in the universe:– Hydrogen 98%

– Helium 2%

– Others (fraction of a percent)

• The Stars are Matter Mill Houses

The Supernova – Stellar Alchemy

• Nearly all the matter present on earth came from super nova remnants

Earth – A Closed System

• Matter, essentially, does not enter or leave the earth

• A miniscule amount enters from meteors.

• Matter must be recycled by ecosystems.

• Chemicals are cycled between organic matter and abiotic reservoirs.

Water Cycling

The Carbon Cycle

The Nitrogen Cycle

The Phosphorus Cycle

Finis