A population is a group of potentially interbreeding
individuals in a given area at a specific point in time. Populations
are dynamic, and their size is the result of a balance of their biotic
potential, and their maximum growth rate assuming ideal conditions and
the limits placed on it by the environment (i.e., food, space, etc.).
Habitats have a carrying capacity, or a maximum number
of individuals of a species the area will support. Some populations
are density dependent, which means that they respond to the carrying capacity
of the habitat by slowing their rate of increase as their numbers
approach the carrying capacity.
There are a number of environmental factors
which can be limiti the size of a given population: availability
of nutrients, light, and competition with other species, which can be measured
by your class in a study of population dynamics.
There also are a number of factors which are
components of the population itself which can effect how the
population will respond to its habitat,which might be of interest to your
students. The age structure, size structure, density, frequency,
cover, and periodicity, as one would find with migratory organisms such
as birds, all influence a population's response to its habitat.
Age structure
Biotic potential
Carrying capacity
Clumped distribution
Cover
Density
Emigration
Environmental resistance
Exponential growth
Frequency
Growth rate
Immigration
Limiting factor
Population
Random distribution
Size structure
Uniform distribution
1. Guadrant sampling plots: plots used to measure the density, frequency and cover of vegetation or in some cases animals. If more than one species is measured relative or percent values for density, frequency and cover can be calculated.
2. Line transacts: a plotless sampling technique to measure density, frequency and cover of vegetation.
3. Tree coring: a method of determining the age structure, fire and hydrological history of trees.
4. Fish scale ring counts: a method for determining the age of fish.
5. Point center quarter method: a plotless method to determine the density, cover and frequency in trees.
6. Soda straw method of determining tree height: a triangulation method of determining the height of trees.
7. Mark and recapture: a method for estimating the size of animal populations in the field - this is accompanied by an in class simulation.
8. Burlazy funnel: a method for sampling invertebrate populations in leaf litter.
9. Simpson's diversity index: a method of calculating the diversity of animal populations.
10. Comparative values: a method of calculating a similarity index for both animal and plant populations for which you have sample plot data.
11. Daubenmire Frames: a mini-plot method for sampling both plant and animal populations from which density and cover can be calculated.
12. Migratory species counts: a method of censusing species which occur in an area periodically.