Basic Ecology I

• Energy• Types of Ecosystems• Productivity• Energy Flow• Trophic levels• Food webs/chains

Energy: the ability to do work

• Moving matter over a distance/ a heat transfer between two objects• Kinetic energy: energy contained in moving objects• Potential energy: stored energy• Heat: energy transferred between objects• High and Low quality energy: concentrated versus diffused• Ie, wind compared to oil

Thermodynamics

• 1st law: energy is conserved

• 2nd law: with energy transfer, less energy becomes available

Potential and kinetic energy

Energy and EcosystemsChemosynthesis

Ecosystems

Productivity

• Limits to Primary production

• Light• Nutrients• Water• Temperature

Energy Source for Ecosystem

• Energy flows through ecosystem

• Not recycled like matter

• Continuous supply• Solar energy

• Enters ecosystem through photosynthesis

Equations for production

• Biomass 1 = biomass 2 – NP (net production)• Three currencies of energy flow: biomass,

energy content, carbon content

Trophic levels

• Autotrophs (Producers)

• Heterotrophs (Consumers)

• Detritivores (Decomposers)

Trophic levels

• Autotrophs (Producers)

• Heterotrophs (Consumers)

• Detritivores (Decomposers)

Chemosynthetic

Light is not the source of energy

Energy & Biomass

Energy and Biomass

Food Chains/Webs

Aquatic Food webs

Limits to Food Chain Length

• Energetic Hypothesis

• Inefficiency of energy transfer

• 10% rule

• Dynamic stability hypothesis (length of chain)

Applications

Human trophic Level

Dependent of where weEat in the food chain.

Should Humans eat lower on theFood Chain?

Biomagnification

Toxic materials: DDT, Hg, Pb

Summary

• Energy determines the limits of the food supply

• Energy is fixed by autotrophs

• Energy flow between levels depends on the efficiency of energy transfer