ENVS 1100 Lecture Notes - Lecture 7: Environmental Impact Assessment, Population Ecology, Logistic Function
3 May 2018
School
Department
Course
Professor
Population Ecology
September 30, 2014
Population ecology examines how populations interact with their abiotic and biotic
environment.
Population – all the individuals of a species that live in the same geographic area
and are able to interact and interbreed
Population Dynamics – the changes over time of population size and composition
Populations fluctuate in size and have varied distributions.
Every population has a minimal viable population, the smallest number of
individuals that would still allow a population to be able to persist or grow, ensuing
long-term survival. This is an important concept when considering how to conserve
endangered or threatened species. A population that is too small may never be able
to recover and is also subject to inbreeding, which allows harmful genetic traits to
spread and weaken the population.
Environmental impact assessment is an evaluation of the positive and negative
impacts of a proposed environmental action, including alternative actions that could
be pursued. These assessments can be conducted to see whether or not a species
should be reintroduced in areas.
Population density – the number of individuals per unit area
• If too low, individuals may have difficultly finding mates (can lead to
inbreeding)
• If too high, can cause increased competition, fighting and spread of disease
Population distribution – the location and spacing of individuals within their
range
• Affected by topography, species characteristics, and habitat makeup
Clumped distribution – individuals are found in groups or patches within the
habitat (deer traveling in herds)
Random distribution – individuals are spread out over the environment
irregularly with no discernible pattern (seed dispersal)
Uniform distribution – individuals are spaced evenly, perhaps due to territorial
behavior or mechanisms for suppressing the growth of nearby individuals (rare in
nature)
Populations display various patterns of growth.
Population growth rate - change in population size over time (births – deaths in a
specific time period)
Determined by:
• Birth rate – number of births per 1000 individuals per year
• Death rate – number of deaths per 1000 individuals per year
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Population ecology examines how populations interact with their abiotic and biotic environment. Population all the individuals of a species that live in the same geographic area. Population dynamics the changes over time of population size and composition. Populations fluctuate in size and have varied distributions. Every population has a minimal viable population, the smallest number of individuals that would still allow a population to be able to persist or grow, ensuing long-term survival. This is an important concept when considering how to conserve endangered or threatened species. A population that is too small may never be able to recover and is also subject to inbreeding, which allows harmful genetic traits to spread and weaken the population. Environmental impact assessment is an evaluation of the positive and negative impacts of a proposed environmental action, including alternative actions that could be pursued.
