Ecology
Chp. 17 pp. 361-379
I.
What is an ecosystem?
a. Can be as large as the whole universe or as small as a drop of water.
b. Boundaries depend on the interest of the observer.
c. Ecosystem- a community and all the physical aspects of its habitat, such as the soil, water, and
weather.
d. Ecology- the study of the interactions of living organisms with one another and with their
physical environment (soil, water, climate…)
e. Habitat- the place where a particular population of a species lives.
f. Community- the many different species that live together in a habitat.
g. The physical aspects of a ecosystem are abiotic factors
h. The living organisms in the habitat are called biotic factors
II.
Diversity within ecosystems
a. Biodiversity- the number of species living within an ecosystem
b. The biodiversity of different ecosystems varies
III.
Ecosystems Change over time.
a. Pioneer Species- the first organism to live in a new habitat.
i. Usually small, fast-growing plants
b. Succession-the progression of species replacing one another
i. Primary succession-succession where there has been no previous growth
1. ex: plants growing in the cracks of dried lake bed
ii. Secondary succession- occurs where plants have previously grown
1. ex: a bush growing in a grassy meadow
IV.
Energy flow within ecosystems
a. Trophic Levels- the level that an organism belongs to in energy movement
i. Producer- capture energy using photosynthesis
1. Plants
2. Bacteria
3. Algae
ii. Consumer- consume plants or other organisms to obtain energy necessary to build their
molecules
b. Food Chain- the path of energy through the trophic levels
i. Producers
ii. Herbivores-animals that eat plants and primary producers
iii. Carnivores-animals that eat herbivores
iv. Omnivores-consume producers, herbivores and carnivores
v. Detritivores-obtain energy from organic waste and dead bodies that is produced at all
trophic levels.
vi. Decomposers- cause decay releasing nutrients back into the environment
vii. Food Web- interconnected group of food chains
c. Energy is lost to the environment at each level
i. Only about 10% of energy is stored in the animal.
ii. Some lost as heat and some used to do work
iii. Biomass-dry weight of tissue and other organic matter found in an ecosystem
iv. More biomass at lower trophic levels
Cycle of materials within ecosystems
V.
a. Biochemical Cycles- closed circles or cycles of materials from nonliving to living organisms
and back to nonliving.
i. Examples of some cycles are:
1. Water, carbon, nitrogen and phosphorus