Introduction to APES Chapter 1-2 notes. HOW DO ECOLOGISTS LEARN ABOUT ECOSYSTEMS? Ecologist go into ecosystems to observe, but also use remote sensors.

Introduction to APES

Chapter 1-2 notes

HOW DO ECOLOGISTS LEARN ABOUT ECOSYSTEMS?

• Ecologist go into ecosystems to observe, but also use remote sensors on aircraft and satellites to collect data and analyze geographic data in large databases.– Geographic Information Systems– Remote Sensing

• Ecologists also use controlled indoor and outdoor chambers to study ecosystems

Geographic Information Systems (GIS)

• A GIS organizes, stores, and analyzes complex data collected over broad geographic areas.

• Allows the simultaneous overlay of many layers of data.

Figure 3-33Figure 3-33

Systems Analysis

• Ecologists develop mathematical and other models to simulate the behavior of ecosystems.

Figure 3-34Figure 3-34

Populations Grow

• Linear growth– Growth by a fixed

amount

• Exponential growth– Growth by a percentage

• Like a bank account

J-Curves

A special kind of exponential growth in which the % changes over time.The human population growth forms a “J” curve:*0.002% for most of human history*2.06% in 1970*1.8% in 1980*1.35% in 2000

Measuring WealthGNP- measurement of economic growth Problem- doesn’t take into account the depletion of resources

GNP per capita- How we measure the wealth of a nationProblem- doesn’t tell how the wealth is distributed

Comparing Countries

More Developed Countries• US, Canada, Japan,

Australia, New Zealand and Western Europe

• --20% of world population; have 85% of wealth

• --Use 88% of resources; make 75% of waste and pollution

Less Developed Countries• All other countries of the

world • --80% of world population;

have 15% of wealth • --use 12% of resources

• Sustainability, is the ability of earth’s various systems to survive and adapt to environmental conditions indefinitely.

• The steps to sustainability must be supported by sound science.

Figure 1-3Figure 1-3

Sustainability: The Integrative Theme

• Environmentally Sustainable Societies

• … meets basic needs of its people in a just and equitable manner without degrading the natural capital that supplies these resources.

Figure 1-4Figure 1-4

Resources• Anything we use to obtain our

needs --renewable or non renewable--recyclable or non recyclable

Resource Scarcity

• Resource scarcity– Absolute- insufficient

or too costly to harvest

– Relative- distribution is unbalanced

i.e.: 1973-1979 Oil not processed and shipped in large enough quantity to meet the needs of MDCs.

POLLUTION

• Found at high enough levels in the environment to cause harm to organisms.– Point source– Nonpoint source

Figure 1-9Figure 1-9

Pollution• Some is caused by natural occurrences, most

is caused by MDCs when developing or using certain resources.

• Effects of pollution– damage to plants– damage to health– disruption of life

World Views

• Whom should we believe?• Controversy over how serious our

environmental problems are.

World ViewsPlanetary Management

• We are the most important species.

• We understand and control the earth.

• Technology will solve problems.

• All economic growth is good & potential is limitless.

Environmental Wisdom

• Nature exists for all species.• We are not in charge of the

rest of nature. • Some growth is

environmentally beneficial, some is harmful. Resources are limited.

• Our success depends on learning to cooperate w/ each other and nature.

Aldo Leopold’s Environmental Ethics

• Individuals matter.• … land is to be loved

and respected is an extension of ethics.

• We abuse land because we regard it as a commodity…

Figure 1-AFigure 1-A

The 7 Steps of the Scientific Method

Step• Observe• Question• Hypothesis

• Test hypothesis• Record results• Form conclusions• Report

Example:• I have a lot of clothes• What should I wear?• If I wear a sleeveless shirt,

then I will be more comfortable.

• Wear a sleeveless shirt• (In my mind)• I am more comfortable. I

accept my hypothesis• To myself

Testing Hypotheses

• Scientists test hypotheses using controlled experiments and constructing mathematical models.– Variables or factors influence natural processes– Single-variable experiments involve a control and

an experimental group.– Most environmental phenomena are multivariable and are hard to control in an experiment.

• Models are used to analyze interactions of variables.

Scientific Reasoning and Creativity

• Inductive reasoning– Involves using specific observations and

measurements to arrive at a general conclusion or hypothesis.

– Bottom-up reasoning going from specific to general.

• Deductive reasoning– Uses logic to arrive at a specific conclusion.– Top-down approach that goes from general to

specific.

MODELS AND BEHAVIOR OF SYSTEMS

• Usefulness of models– Complex systems are predicted by developing a

model of its inputs, throughputs (flows), and outputs of matter, energy and information.

– Models are simplifications of “real-life”.– Models can be used to predict if-then scenarios.

THE NATURE OF ECOLOGY

• Ecology is a study of connections in nature.– How organisms

interact with one another and with their nonliving environment.

Figure 3-2Figure 3-2

What Sustains Life on Earth?

• Solar energy, the cycling of matter, and gravity sustain the earth’s life.

Figure 3-7Figure 3-7

EcologyEco- = interactions between organisms-ology = study

Biosphere- where living things exist Living and non-living component

- thin layer of soil, air and water 8 km deep into ocean and 8 km in atm

Biome = geographical area defined by environmental conditions

i.e.: desert, aquatic, grassland

Ecology Terms

Ecology TermsEcosystem- unit of the biosphere where matter and energy are transferred as organisms interact with their living and nonliving environment.

-Natural boundary-

i.e.: pond, log in forest, forest as whole*Size depends on what is being discussed

Population- group of same species(able to mate and produce fertile offspring)

Community- many species interacting

Habitat- part of ecosystem where the animal lives

niche- specific role the organism plays

Ecology Terms

Homeostasis

• “Steady state”- leads to stability– in a living system– in an ecosystem

• “Steady state”- leads to stability• -in a living system• -in an ecosystem

3 Elements Control Homeostasis• 1. receptor or sensor-detects condition• 2. comparator- evaluates information• 3. effectors- executes command

– Coupled positive and negative feedback (like a thermostat)

3 Elements Control Homeostasis

Negative feedbackEx: temperature rises, air cooler comes on

temperature drops, air cooler goes off

Positive feedbackEx: Increased body temperature, body sweats•Continued rise in temperature overloads system until sweating can’t cool down, death from heat stroke

Feedback Loops: How Systems Respond to Change

• Outputs of matter, energy, or information fed back into a system can cause the system to do more or less of what it was doing.– Positive feedback loop causes a system to change

further in the same direction (e.g. erosion)– Negative (corrective) feedback loop causes a system

to change in the opposite direction (e.g. seeking shade from sun to reduce stress).

Feedback Loops:

• Negative feedback can take so long that a system reaches a threshold and changes.– Prolonged delays may prevent a negative

feedback loop from occurring.

• Processes and feedbacks in a system can (synergistically) interact to amplify the results.– E.g. smoking exacerbates the effect of asbestos

exposure on lung cancer.

SynergismThe effect of 2 or more stimuli is more than the additive effect

Ex 1: smoking & asbestos cause lung cancerWhen a person is exposed to both, he has 10X more

chance of getting lung cancer than a simple additive effect.

Ex 2: Chlorofluorocarbons destroy ozone & enhance the Greenhouse Effect

More UVb rays enter atmosphere, killing phytoplankton so less CO2 is absorbed by ocean•Theory* Results in intense acceleration of global warming