Environmental Science - Chapter 5: Section 5-3 Page 3

What are LIMITING FACTORS?

A number of physical or chemical factors that can help to determine the number of organisms in a population, sometimes one or more factors are more important than others in regulating population growth.

What is another limiting factor in aquatic life zones?

SALINITY, the amounts of various inorganic minerals or salts dissolved in a given volume of water.

A higher population density can help what?

Sexually reproducing individuals to find mates more easily in order to produce offspring and increase the size of a population.

What is another limiting factor on land?

Soil nutrients.

What is the ecological principle is called the LIMITING FACTOR PRINCIPLE?

TOO MUCH OR TOO LITTLE OF ANY PHYSICAL OR CHEMICAL FACTOR CAN LIMIT OR PREVENT THE GROWTH OF A POPULATION, EVEN IF ALL OTHER FACTORS ARE AT OR NEAR THE OPTIMAL RANGE OF TOLERANCE.

What are important limiting physical factors for populations in AQUATIC LIFE ZONES, or water-filled areas that support life?

Temperature, sunlight, nutrient availability, acidity, and the low levels of oxygen gas in the water (DISSOLVED OXYGEN CONTENT).

What is a population in an ecosystem's RANGE OF TOLERANCE?

Tolerance range to variations in its physical and chemical environment. Individuals within a population may also have slightly different tolerance ranges for temperature or other physical or chemical factors because of small differences in their genetic makeup, health, and age.

How can too much of a physical or chemical factor can also be limiting?

Too much water or fertilizer can kill plants.

What is an example of tolerance range?

A trout population may do best within a narrow band of temperatures (OPTIMUM LEVEL OR RANGE), but a few individuals can survive above and below that band. Of course, if the water becomes much too hot or too cold, none of the trout can survive.

How is temperature a limiting factor?

Both high and low temperatures can limit the survival and population sizes of various terrestrial species, especially plants and many insect species.

What is an example of soil nutrients serving as a limiting factor on land?

If a farmer plants corn in phosphorus-poor soil, even if water, nitrogen, potassium, and other nutrients are at optimal levels, the corn will stop growing when it uses up the available phosphorus.

What is an example of how some limiting factors become more important as a population's density increases?

In a dense population, parasites and diseases can spread more easily and have the effect of controlling population growth.

What is an example of precipitation serving as a limiting factor?

Low precipitation levels in desert ecosystems limit desert plant growth.

What is another factor that can limit the sizes of some populations?

POPULATION DENSITY, the number of individuals in a population found within a defined area or volume.

Different species and their populations thrive under different what?

Physical and chemical conditions.

What is often the limiting factor on land?

Precipitation.

What are some examples of different condition needs?

Some need bright sunlight; others flourish in shade. Some need a hot environment; others prefer a cool or cold one. Some do best under wet conditions; others thrive in dry conditions.