ENVS 130 Exam 2

The number of children born in a year per 1,000 women within an age group.

A graphical illustration of a population distrubted by age and gender.

One who studies the factors influencing the size, density, and distrubution of human populations.

Illustrates the transition between the 4 stages in birth rates, death rates, and growth rate of human populations associated with economic development.

3rd stage of demographic transition in which continued economic development leads to lower birth rates.

The percentage of infants who die in an population before age 1.

The average age that a infant born at a given time, will be likely to live. Provides a summary of differences in survivorship.

2nd demographic stage where improved economic conditions relieves stress on resources. As a result, mortality rate decreases while birth rate stay relatively high or even increases.

A calculation between the difference between immigration and emigration per 1,000 individuals in the population.

Also known as "Pre-Industrial", stage 1 of the demographic model in which mortality and fertility rates are high. The population is stable.

4th stage of demographic model that is characterized by low birth, death, and population growth rates.

Energy contained in living or dead organic matter.

Assemblages of plants and animals that are able to perpetuate themselves generation after generation.

A relationship where one organism benefits and the other doesn't but is unharmed.

A postulate that 2 species that compete for a resource cannot coexist. One species will eventually displace the other.

In refrence to the food web, a species that feeds on another organism.

An organism that feeds on non-living organic matter.

Species that interact in a given area.

Events such as fires, hurricanes, etc. that could result in the loss of many or all species in an ecological community.

The transfer and transformation of high-energy organic molecules within ecological communities.

In the competition for resources, the ability to gain resources more quickly or efficently.

Species alter the enviornment in a way that makes it more habitable for other species. This is important in the early events of succession.

Feeding relationships among species is depiced on a food chain. One species in a trophic level is eaten by another, and this one by another, and so on.

Feeding interactions between species in an community.

The total amount of CO2 that photosynthetic organisms can convert to organic carbon each year.

An organism that consumes only plants.

In the comp. for resources, fending off would-be competitiors using agressive tactics, for plants this could be using toxic chemicals.

Interactions between different species as they compete for shared resources.

Where members of the same species compete for resources.

Species that play a significant role in the abundance of other species and considered essential to the health of the ecosystem.

A relationship in which two organisms benefit from an interaction.

GPP minus the total amount of carbon from green plants.

The dividing up of resources that make up a fundamental niche by potential competitors; so that they may coexist.

The reforestation of old farmland.

A organism that lives in or on another, without killing them directly.

The early colonists of a new enviornment. They are widely dispersed and able to grow in very harsh and resource poor conditions. As they grow, they alter the enviornment to make other plants grow as well.

A organism that hunts another.

A organism that's hunted by a predator.

An organism that feeds on plants. (10% of energy is transfered after consuming plants.)

An organism that gains energy from the sun and photosynthesis to produce it's own energy. (100% of energy transfered from the sun.)

After a disturbance has removed virtually all ecological legacies, plants, animals, and micorscopic organsims slowly colonize the disturbed area. This occurs slowly, often over years or potentially milennia.

The process of change following disturbances that leave behind legacies such as soil, woody debris, or plant seeds.

The process of post-disturbance change in an ecological community.

Intimate interdependencies between species.

Classifications of organisms based on their food source; for ex. primary producers, herbivores, and carnivores.

The fraction of energy that the organisms in one trophic level store as biomass and make avaliable to the next trophic level.

The influence carnivores across multiple trophic levels. For ex. loss of carnivores may result in the increase of herbivores and their overpopulation.