1 INTRODUCTION TO

ECOLOGY and ECOSYSTEM CONCEPTS

Case Study: Deformity and Decline in Amphibian Populations

•  High incidence of deformities in amphibians

•  Declining populations of amphibians worldwide

•  ECOLOGISTS’ ROL E IS TO FIND ANSWERS:  Amphibian population declines

were recent.  Many declining populations

were in pristine or protected areas.

 Amphibians are “biological indicators” of environmental problems

Figure 1.1 Deformed Leopard Frogs

faculty.sxu.edu/~cochran/ecoweb09/ecointro.ppt

HUMANS & ECOLOGY…

• Humans have enormous impact on the planet.

• Humans are part of global environment.

• We must understand how natural systems work.

• Ecology is the field of Biological Science that studies the functions of natural systems.

WHAT ECOLOGY IS….AND IS NOT • Ecology is not “Environmentalism” • Ecology is not “Natural History”

• Ecology is a Science

 “The study of the patterns and processes that determine the distribution and abundance of organisms.”

 Based on observations, hypotheses, empirical tests, theory, models and more tests!

ECOLOGISTS VS NATURALIST VS ENVIRONMENTALISTS

Example: Consider the American Robin, Turdus migratorius

• Naturalist: Observes robins and paints/photographs/ writes/composes music about robins. Provides valuable “Natural History.”

• Ecologist: Asks, “What causes the robin’s singing behavior? Seeks to explain the Natural History.

• Environmentalist: Seeks action to preserve the habitat of the robin.

faculty.sxu.edu/~cochran/ecoweb09/ecointro.ppt

Ecology is a branch of biology.

Environmental science incorporates concepts from the natural sciences (including ecology) and the social sciences, and focuses on solutions to environmental problems.

Ecology is the scientific study of interactions between organisms and their environment.

Ernst Haeckel (1869) & ECOLOGY • The scientific study of the interactions

between organisms and their environments

•  “By ecology we mean the body of knowledge concerning the economy of Nature - the investigation of the total relations of the animal to its inorganic and organic environment.”

• The leading German disciple of Charles Darwin

• Originally used the Greek spelling Oecologie, and defined it as “the science of the relations of living organisms to the external world, their habitat, customs, energies, parasites, etc.”

faculty.sxu.edu/~cochran/ecoweb09/ecointro.ppt

FROM OECOLOGIE TO ECOLOGY…

• Haeckel derived the new label from the same root found in the older word “economy” (“Oekonomie”):  the Greek oikos, referring originally to the

family household and its daily operations and maintenance

• The reason was that at that time, people thought that national economic affairs could be understood as an extension of the housekeeper’s budget.

 Haeckel thought that the Earth constituted a single economic unit

COINING THE TERM…

• Burdon-Sanderson (1890s): Elevated Ecology to one of the three natural divisions of Biology: Physiology - Morphology – Ecology Andrewartha (1961): “The scientific study of the distribution and abundance of organisms.”

• Odum (1963): “The structure and function of Nature.”

TO STANDARDIZE OUR DEFINITION…

• Charles Krebs. Studies migration and population dynamics in lemmings and other small mammals.

• (1972) Ecology is the scientific study of the interactions that determine the distribution and abundance of organisms.

THUS… • the study of the interactions between organisms and

their environment

• the study of the distribution and abundance of organisms

• KEY POINTS: • Interactions - between everyone and everything

• Organisms - all taxa are fair game

• Environment - includes ABIOTIC and BIOTIC factors outside the organism

• Abundance - population sizes • Distribution - where we find organisms?

Official ESA Definition*

• Ecology is “The scientific discipline that is concerned with the relationships between organisms and their past, present and future environments, both living and non-living.”  Understanding these relationships will

explain the patterns of distribution and abundance

* August 2000 Annual Meeting of the Ecological Society of America

WHY STUDY ECOLOGY? • Curiosity – How does the world around us work? How are we

shaped by our surroundings?

• Responsibility – How do our actions change our environment? How do we minimize the detrimental effects of our actions? Overfishing, habitat destruction, loss of biodiversity, climate change.

• Nature as a guide – The living world has been around much longer than we have and has solved many problems with creative solutions. Ecological systems are models for sustainability. How can we feed our growing population? Where will we live?

• Sustainability – a property of human society in which ecosystems (including humans) are managed such that the conditions supporting present day life on earth can continue.

• Ecology helps us understand complex problems.

1 ECOSYSTEM CONCEPTS

The Earth environment is the home (habitat) of all forms of life including humans. All life forms depend on the proper functioning of our environment!

ECOSYSTEM – basic unit and probably the most important concept in ecology

Two Types of System:

1. Open system – presence of inputs and outputs (matter and energy)

2. Closed system – no exchange of matter and energy (usually artificially made, e.g. terrarium)

ECOSYSTEM

• an ecosystem consists of all the organisms and the abiotic pools with which they interact (Chapin)

• an ecosystem is the sum of all of the biological and nonbiological parts of an area that interact to cause plants to grow and decay, soil or sediments to form, and the chemistry of water to change (John Aber and Jerry Melillo)

EXAMPLE OF ECOSYSTEMS (CLOSED AND OPEN)

Controls over ecosystem processes: state factors, interactive controls, and feedbacks

STATE FACTORS

• State factors set boundary conditions – Hans Jenny (1941)  Climate – broad geographic influence

on biome distribution  Parent material – local influence on soil

type  Potential biota – what organisms can

occupy a site  Topography – microclimate  Time – evolution, weathering

INTERACTIVE FACTORS

• Interactive controls: factors that both control and are controlled by ecosystem characteristics.  Resources: energy and materials used to

support organisms’ growth and maintenance  Modulators: physical and chemical

properties that affect organisms’ activity, but are neither ‘consumed’ nor depleted

 Disturbance, Biotic Community, Human Activities

FEEDBACKS

•  negative feedbacks – homeostasis – when two components of a system have opposite effects on one another

 predator – prey  Thermostat

•  positive feedbacks – when two components of a system have the same effect (positive or negative) on each other

  runaway greenhouse effect – rising CO2 increases temperature, increasing respiration, increasing CO2

  legumes and Rhizobium in nitrogen-fixing mutualisms – each provides key resource to the other

•  IN GENERAL:  Negative feedbacks are key to maintaining ecosystems in a

given state, because they resist change  Positive feedbacks, if unchecked, have the potential to shift

ecosystems from one state to another

BIOTIC COMPONENTS ABIOTIC COMPONENTS   Producers

  Green Plants   Algae (Phytoplankton)

  Consumers   Herbivores   Carnivores   Omnivores

  Decomposers   Detritivores   True decomposers   Bacteria and fungi

  Climatic Factors   Light   Temperature   Precipitation   Wind   Humidity

  Edaphic Factors   Soil Nutrients   Soil Moisture   Soil Ph

  Hydrological Factors   Physicochemical factor

FOUR LAWS OF ECOLOGY

1.  EVERYTHING IS CONNECTED TO EVERYTHING ELSE

2.  EVERYTHING MUST GO SOMEWHERE

3.  NATURE KNOWS BEST

4.  THERE IS NO FREE LUNCH

1 NEXT MEETING: ENERGY FLOWS IN AN ECOSYSTEM

MINI SKIT TIME….