I. Definitions/terms (overview fig. 3-2)
A. ecology
B. organisms
C. species
D. population
E. community, ecosystem, biosphere
II. Ecosystem basics and components
A. major ecosystem types are also called biomes. We will survey the major types later. See overview fig. 3-9
B. Two ecosytems meet at an “edge” or ecotone. These zones have a higher diversity of life because life from both zones mix here
C. Living creatures are called the biotic components of the ecosystem
D. Non-living elements are the abiotic components. Examples listed in your text.
- limiting factors
- range of tolerance
E. Biodiversity can be described at four levels: ecological, species, genetic, and functional (see p. 62)
III. How it all works: energy flow (check out some definitions and diagrams of food webs) (more examples)
A. With a few exceptions, all energy comes from the sun and is captured by producers
- more on hydrothermal vents
- journey to deep sea vents
- another vents page -- black smokers
- learn more about phytoplankton - the producers of the ocean
B. Other creatures are consumers of various types – see definitions p. 60-61
C. Constant energy inputs from the sun are required; materials are recycled (fig 3-14)
D. Energy flow is often described as a food chain (fig. 3-17) but is better depicted as a food web (fig.3-18). Note that even the web in 3-18 is simplified!!
- Other unusual feeding relationships: squirrels have been known to eat quails and chipmunks; chimpanzees hunt and eat small monkeys
- Predators sometimes eat other predators when the going gets tough as well
- check out examples
- Walking with ghosts - a research project into boreal forest food webs
- Animal migrations are often linked to food availability - check out the top 10 amazing animal journeys
- Video of a fox feeding on a moose carcass
- wolves in Yellowstone (includes video)
E. Food webs can be arranged in trophic levels and are described as pyramids:
1. pyramid of energy – 10% flows to the next level – fig. 3-19
2. pyramid of biomass (lots of details here)
3. pyramid of numbers
F. Primary productivity – see description and calculation p. 66 and fig. 3-21
1. satellite measurement of GPP – fig. 3-20 | more details here
2. comparison of NPP in various ecosystems – fig. 3-22
A. water – fig. 3-26 – note contrast between surface runoff and groundwater (another link)
- water cycle animation
- This animation connects the water cycle with the rock cycle and the tectonic cycle
- more info - NASA Earth Observatory
B. carbon – fig. 3-27 | another diagram | animation/tutorial | another animation
1. photosynthesis and respiration are the primary biological processes that affect carbon levels (compare to GPP and NPP)
2. chemical and geological processes are an important factor as well
- creation of fossil fuels
- "sequestration" of carbon in the ocean and marine sediments
3. human effects on the cycle (deforestation, burning of fossil fuels) will be discussed later. Also see fig.3-28.
C. Nitrogen – fig. 3-29(another diagram)
1. nitrogen fixation by bacteria is the key process (N2 and NH3)
2. human alterations (fertilizer production, excess nutrients, acid rain) will be discussed later (see also fig. 3-30)
D. phosphorus – fig. 3-31 (animation/tutorial) - note importance of guano
E. sulfur – fig. 3-32 - note importance of volcanoes and H2S
V. The notion of ecosystem services has become an important way to quantify the benefits of ecosystems to humans and to a natural environment (more info) (and more from American Forests on the value of trees)