Notes: Unit 1
Ecosystems and Biomes
1. Environmental Science is the interdisciplinary field of
study of human impact on the world.
2. The term environment is used to describe the total
surroundings of an organism including other plants and
animals that affect the organism during its lifetime.
3. Ecology is the study of the interactions among all
organisms and their environment.
4. An Ecosystem is a community of living organisms and their
environment, both abiotic and biotic. Ecosystems may be
small (e.g., log) or large (e.g., forest).
5. Similar organisms that can interbreed and produce fertile
offspring are called Species.
6. Populations are groups of similar species living in the same
area at the same time.
7. A Community is an assembly of different populations that
live together in a defined area. A community includes
producers, consumers, decomposers, saprophytes, and
detritovores.
8. Biomes are large areas made up of several ecosystems
that share the same climate and dominant plant communities.
9. Major Biomes include:
1. Tundra
2. Taiga
3. Temperate Forests
4. Grasslands
5. Chaparral
6. Deserts
7. Rainforests
10. Climate is the prevailing weather conditions in an area
over time. Climate plays a major role in determining the
distribution of organisms on our biosphere. The major
components of climate are temperature, precipitation, light
and wind. (Abiotic factors)
11. Temperature is mainly determined by Latitude (degrees
North or south of the equator) and Altitude. Temperature is
also greatly influenced by proximate to large bodies of
water, such as oceans. For every 1000 meter increase in
altitude there is a temperature decrease of 10oC.
12. Windward sides of mountains are often wet due to
orographic precipitation. Leeward sides are dry
(rainshadow). Deserts are often found on leeward sides of
mountain ranges.
13. Mountain sides with Southern exposures receive more
light in northern latitudes and therefore they often have
different vegetative characteristics then mountainsides with
northern exposures. The reverse is true in the southern
hemisphere.
14. Limiting Factors are any conditions that limit a
population’s growth. Factors include the amount of food,
water and shelter, the number of predators, and disease.
15. Limiting factors can be Density dependent (competition,
predation, parasitism or disease) or density independent
(weather, fire, clear cutting, etc)
16. An organism's niche is the conditions under which it can
successful survive and reproduce. These conditions include,
temperature, amount of water, available nutrients, pH range,
etc. Each organism has a range of tolerance within which it
can live. (ex. A certain temperature range, the amount of
water it can tolerate, the amount of saltwater in can live in,
etc.)
17. Ecological Succession is a community change in which new
populations of organisms gradually replace existing ones.
18. Primary succession begins in an area where there was no
existing community, such as a volcanic island. This rarely
occurs.
19. Secondary succession occurs in an area where the
existing community is only partially destroyed. (e.g., light
fires, wind damage, etc.). Very common.
20. Pioneer species are the first group of organisms to
occupy an area undergoing primary succession. Pioneer
species tend to be short lived, reproduce rapidly and have
minimal requirements (e.g., mice, weeds, insects, etc.)
Sometimes referred to as r-selected.
21. Climax communities are stable and well established and
have high diversity. Climax species are long lived, and have
low reproductive rates (deer, cougar, eagle, oak tree etc).
They are sometimes referred to as K-selective.
22. Adaptations in plants and animals occur as living
conditions change over long periods of time. The process of
developing adaptations is called Natural Selection.
23. Natural selection is driven by selection pressures such
as availability of water, sunlight, food, and predator prey
relationships.
Aquatic Ecosystems/Biomes:
24. Two important aquatic ecosystems are Marine and
freshwater.
25. Salt water (35/1000 ppt) covers 75 % of the Earth’s
surface. This marine environment is made up of several
zones:
1. Intertidal zone (Littoral) – the area along coastlines
between high and low tides. Experiences extreme
variations in temperature, moisture and salinity.
2. Coastal zone (Neretic) – the region of water over the
continental shelf. Highly productive due to the rich
supply of nutrients and warmer temperatures.
3. Oceanic zone (Pelagic) – vast open ocean.
Unproductive. Benthic communities are sparse due to
lack of sunlight.
26. The intertidal zone (Littoral) include three subzones:
upper, middle and lower. The upper is only submerged during
spring tides and the lower exposed only during spring tides.
27. Estuaries are shallow marine areas where salt water and
fresh water mix. The richest estuary in the world is the
Chesapeake Bay.
28. Fresh water makes up less than 3 % of the Earth’s
biosphere. Yet fresh water is vital to nearly half of the
Earth’s organisms.
29. The study of fresh water lakes and ponds is called
Liminology.
30. Four important freshwater ecosystems include: rivers,
lakes wetlands and vernal pools.
31. Wetlands are among the richest and most valuable
terrestrial biomes. They serve as vital nurseries to a variety
of wildlife, especially birds. Wetlands also act to filter
pollution, reduce siltation, and reduce flooding by acting as a
natural sponge to store water. Coastal wetlands protect the
mainland from erosion caused by storms and hurricanes.
32. A type of vital terrestrial wetland ecosystem for
amphibians and some other organisms are Vernal pools.
These pools dry out during the summer and therefore do not
contain predator fish that would eat larval amphibians. Most
are small and over looked. [Vernal = spring]