- Conditions vs. resources
- Growth and survival
- Law of Limiting Factors
- Habitats and niches


[SLIDE 1]

Conditions are factors that vary in space and time but that are not made unavailable by other species. These include temperature, wind, fire, salinity and pH.

Resources are any factors that are consumed by organisms. These include water, chemical nutrients, oxygen, food and space.


[SLIDE 2]

Optimum levels are the best levels at which organisms grow and survive. These levels involve a variety of factors such as temperature, salinity and more.

The range of tolerance includes the entire span within which growth occurs.

The points at the high and low ends of the range are called limits of tolerance.

Stress happens beyond these levels. When there is too much stress, the organism cannot survive.


[SLIDE 3]

Every species has an optimal range, zones of stress and limits of tolerance. These vary between species. Some plants can tolerate cold temperatures, others cannot. Some require freezing temperatures to complete their life cycles.


[SLIDE 4]

In 1840, Justus von Liebig studied the effects of chemical nutrients on plant growth. He noticed that restricting any nutrient limited plant growth. He formulated the Law of Limiting Factors. 

Limiting factor is any factor that limits growth. It can also be a problem of too much instead of too little.


[SLIDE 5]

Habitat refers to the kind of place defined by the plant community and the physical environment where a species is biologically adapted to live. Different types of forests have different habitats.

A niche is the sum of all the conditions and resources under which a species lives. This includes what and where it feeds, what it feeds on, where it finds shelter and nests, and how it responds to abiotic factors.