Ecology

2 Pages 485 Words

Ecosystems
An ecosystem is the simplest entity that can sustain life. At its most basic, an ecosystem consists of several species and a fluid medium (air, water, or both); it sustains two processes, the cycling of chemical elements and the flow of energy.

Ecology: Scientific study of relationships between organisms and their environment
The living part of an ecosystem is the ecological community, which is a set of species connected by food webs and trophic levels.
A trophic level: Group of organisms with the same relative position within the food chain.
(troph = nourishment)

Trophic levels
1st Trophic Level referred to as Producers or autotrophs (auto = self).
are organisms which make their own food from inorganic chemicals and a source of energy.
E.g. green plants blue-green algae and bacteriu
2nd Trophic Level: Consumers = Heterotrophs (hetero = other, different). Primary consumers = herbivores E.g. grasshoppers, cows
3rd Trophic level:
Carnivore (secondary) Consumers: lynx, meadowlarks.
4th Trophic level:
a. Omnivores: (eat plant and animals) e.g. humans, black bears.
b. Tertiary consumers E.g. carnivores which eat carnivores (hawks, bass)
c. Decomposers/scavengers: E.g. live off the dead biotic remains and wastes (earthworms, beetles).

Dominance: refers to the species that are most abundant or otherwise most important within the community.
In the hotsprings certain bacteria survive better at some temperatures than others. Therefore the springs are coloured by the dominant bacteria according to temperature

Terrestrial Food Web
1st Trophic: grasses, herbs, trees
2nd Trophic: herbivores that graze upon the grasses (mice, pine borers, deer)
3rd Trophic: Carnivores (spiders, hawks [3 & 4 level]
4th Trophic: Omnivores (black bears, people)

Oceanic Food Web
more complex than terrestrial food webs
1st Trophic: phytoplankton live on the surface environment of the ocean. Algae.
2nd Trophic: h...