The bioenergetics of habitat refers to the amount of
energy or food available to organisms. This energy is based upon
the primary productivity through photosynthesis of the autotrophic organisms
(plants) which reside in the habitat.
There is great variability in the productivity of
different systems - rain forests are high, deserts low. Key factors
which limit productivity are temperature, water, light and availability
of nutrients. Your students may want to measure these factors, or
the productivity itself. Productivity is usually measured
as some byproduct of photosynthesis, such as the uptake of carbon dioxide,
release of oxygen, harvest of biomass or even the concentration of chlorophyll.
The primary productivity makes it possible for the
heterotrophic animals and decomposers to exist. The amount of energy
stored at this level is the secondary productivity of the habitat.
It is made possible because of the relationships which create the
food chains and webs existing in the habitat.
The second law of thermodynamics describes the
total amount of usable energy as decreasing as it goes through these chains
and webs. This energy is the loss through respiration. Students will
find interesting the delicate balance and complexity of the relationships
between organisms to maintain the energy flow necessary for a healthy habitat.
They will also have an opportunity to see the role biodiversity plays in
this balance.
Autotrophic
Biodiversity
Biomass
Carnivore
Consumer
Decomposer
Detrital food chain
First law of thermodynamics
Food chain
Food web
Grazing food chain
Herbivores
Hetertrophic
Omnivore
Photosynthesis
Primary productivity
Respiration
Secondary productivity
Second law of thermodynamics
Trophic levels
1. Light and dark bottle: a method of measuring primary productivity of water systems.
2. Chlorophyll concentration: by measuring the chlorophyll concentrations of plankton samples and indirect measure of primary productivity can be obtained.
3. Factors effecting elodea productivity: the uptake of carbon dioxide is measured using bromothymel blue to study the effects of differing intensities and wave lengths of light on elodea productivity.
4. Biomass harvesting: the amount of biomass produced is measured by harvesting both above ground and below ground portions of plants.
5. Dimension analysis: the girth of trees is measures to measure forest productivity.
6. Food web construction: a classroom activity using string to simulate the construction of a food web.