Unit 6 Test
Abiotic factors: are non-living. They include the physical and chemical factors that affect the
ability of organisms to survive and reproduce; some examples of abiotic factors are light,
temperature (heat), chemical products, water and atmosphere.
Light constitutes the main supply of energy for organisms. Plants with chlorophyll can change
the light energy into chemical energy via the process known as photosynthesis. This chemical
energy is stored in complex organic substances that are used for growth, development of
flowers and the production of fruit/seeds. Many plants have adapted to high or low light
conditions; shade tolerant plants can dominate the understory of dense forest canopies. Light
also regulates many biological rhythms of a large amount of species of both plants and animals.
Plants use a photoreceptor protein (e.g., phytochrome or cryptochrome) to sense seasonal
changes in photoperiod. This signals anthesis, which is the development of flowers.
Niche: species occurring in “environmental space”;
the space that an organism occupies, which is
confined by environmental variables to which the
Hutchinson (1957) provides a basic definition: “niche
is the set of biotic and abiotic conditions in which a
species is able to persist and maintain stable
The fundamental niche is defined by the
environmental conditions in which a species can
survive and persist; however the species may not be
present within all of this space. The realized niche
includes the environmental and ecological conditions
under which a species actually exists and persists.
Habitat: the environment in which a species is known to occur. Which is influenced by biotic
and/or abiotic environmental variables. Higher habitat diversity is often correlated with higher
species richness in ecosystems.
Functional traits: define species in terms of their ecological roles within an ecosystem. These
traits determine how a species will interact with other species and the environment.
Functional diversity: it accounts for the diversity of functional traits of all the the species in a
Trait: is a measurable property of an organism that influences its performance and species
have functional traits that are uniquely adapted to the ecological niche.
Competitive exclusion principle: EX - The shade tolerant species are at an advantage in the
woodlot understory because they are able to competitively exclude other species of tree
seedlings from establishing that are not shade tolerant.
Ecosystem engineering: Some organisms can control