Chapter 3 Ecosystems and Energy Ecology o Ecology

Chapter 3 Ecosystems and Energy

Ecology o Ecology • • • “eco” house & “logy” study of The study of interactions among and between organisms in their abiotic environment Broadest field in biology o Biotic- living environment o Abiotic- non living or physical environment

Ecology o o Biology is very organized Ecologists are interested in the levels of life above that of organism

Ecology Definitions o Population o Community o Ecosystem

Ecology o Biosphere contains earth’s communities, ecosystems and landscapes, and includes: • Atmosphere- • Hydrosphere- • Lithosphere-

Energy o The ability or capacity to do work • o Chemical, radiant, thermal, mechanical, nuclear, electrical Energy exists as: • • Stored energy (potential energy) Kinetic energy (energy of motion)

Thermodynamics o o Study of energy and its transformations System- the object being studied • • Closed System- Does not exchange energy with surroundings (rare in nature) Open Systemexchanges energy with surroundings

Laws of Thermodynamics o First Law of Thermodynamics • Energy cannot be created or destroyed; it can change from one form to another • o Ex: organisms cannot create energy they need to survive- they must capture it from another source Second Law of Thermodynamics • Systems tend towards disorder- Entropy • When energy is converted form one form to another, some of it is lost. Much of it as heat.

Photosynthesis o Biological process by which energy from the sun (radiant energy) is transformed into chemical energy of sugar molecules 6 CO 2 + 12 H 2 O + radiant energy C 6 H 12 O 6 + 6 H 2 O + 6 O 2 o Energy captured by plants via photosynthesis is transferred to the organisms that eat the plants

Cellular Respiration o The process where the chemical energy captured in photosynthesis is released within cells of plants and animals C 6 H 12 O 6 + 6 O 2 + 6 H 2 O 6 CO 2 + 12 H 2 O + energy o This energy is then used for biological work • Creating new cells, reproduction, movement, etc.

Photosynthesis and Respiration

o Energy Flow Passage of energy in a one-way direction through an ecosystem • • • Producers Primary consumers Secondary consumers Tertiary and Quaternary consumers Decomposers

Food Chains- The Path of Energy Flow o Energy from food passes from one organisms to another • Each “link” is called a trophic level

Food webs represent interlocking food chains that connect all organisms in an ecosystem

Ecological Pyramids o Graphically represent the relative energy value of each trophic level • o Important feature is that large amount of energy are lost between trophic levels to heat Three main types • • • Pyramid of numbers Pyramid of biomass Pyramid of energy

Pyramid of Numbers o Illustrates the number of organisms at each trophic level • • o Usually, organisms at the base of the pyramid are more numerous Fewer organisms occupy each successive level Do not indicate the biomass of the organisms at each level or the amount of energy transferred between levels

Pyramid of Biomass o Illustrates the total biomass at each successive trophic level • • o Biomass: measure of the total amt of living material Biomass indicates the amount of fixed energy at a given time Illustrates a progressive reduction in biomass through trophic levels

Pyramid of Energy o Illustrates how much energy is present at each trophic level and how much is transferred to the next level • o Most energy dissipates between trophic levels Explains why there are so few trophic levels • Energy levels get too low to support life

Ecosystem Productivity o Gross Primary Productivity (GPP) • o Net Primary Productivity (NPP) • • o Total amount of energy that plants capture and assimilate in a given period of time Plant growth per unit area per time Represents the rate at which organic material is actually incorporated into the plant tissue for growth GPP – cellular respiration = NPP • Only NPP is available as food to organisms

Variation in NPP by Ecosystem

Human Impact on NPP o Humans consume more of earth’s resources that any other animal • • o o Humans represent 0. 5% of land-based biomass Humans use 32% of land-based NPP! This may contribute to loss of species (extinction) Humans’ high consumption represents a threat to planet’s ability to support both human and non-human inhabitants