1. Ecological Succession
Ecological Succession: Secondary
Disturbances (fire, flood, windstorms) can disrupt a community.
After a disturbance, new species of plants and animals might occupy the habitat.

2. Secondary Succession
Begins in a place that already has soil and was once the home of living organisms
Occurs faster and has different pioneer species than primary succession
Example: after forest fires

4. Climax community
A community that has reached a stable stage of ecological succession
Grasses in prairies
Cacti in deserts

5. Extinction Rates
The gradual process of becoming extinct is known as background extinction.
Mass extinctions: When a large percentage of all living species become extinct in a relatively short period of time.

6. Estimated number of Extinctions since 1600
Group
Main-land
Island
Ocean
Total
Approximate Number of Species
Percent of Group Extinct
Mammals 30 51 4 85
4000
2.1
Birds 21 92
113
9000
1.3
Reptiles 1 20
6300
0.3
Amphibians 2
4200
0.05
Fish 22 23
19,100
0.1
Invertebrates 49 48 98
1,000,000+
0.01
Flowering Plants
245
139
384
250,000
0.2
Since the mid-1970s there has been an alarming decrease of amphibian populations, and many are on the verge of extinction.

7. Biome
Large geographic areas with similar climates and ecosystems

8. Major terrestrial biomes include
Tropical forest
Desert
Temperate Grassland
Savanna
Temperate broadleaf forest
Coniferous forest (Taiga)
Tundra
(see descriptions pages )

9. Major aquatic biomes Lakes Rivers Estuaries Intertidal zone
Marine pelagic zone
Coral reefs
Marine benthic zone (benthic zone is sea/lakefloor)
See pages

10. Biogeochemical Cycles (Matter moving through the environment)
All living organisms need certain elements/compounds for life processes
Ex: your cells need C,H,O,P,N & S in order to live and reproduce (make more cell)
Cycles in nature keep these elements “moving” from organisms to organism (and sometimes into the atmosphere)

11. Biogeochemical Cycles (Matter moving through the environment)
The flow of a nutrient from the environment to living organisms and back to the environment
Main reservoir for the nutrient is in the environment
Transfer rates to and from reservoir are usually lower than the rates of exchange between and among organisms.
Matter is recycled through an ecosystem – not one way flow

12. Hydrologic (Water) Cycle

14. Nitrogen Cycle
Nitrogen is used in amino acids and nucleic acids (all living organism need nitrogen to make proteins)
Main reservoir is nitrogen gas in the atmosphere
Decomposers are vital to convert ammonia into:
usable nitrites & nitrates for plants (nitrogen fixation)
nitrogen gas (denitrification = puts it back into the atmosphere)

16. Phosphorus Cycle
Phosphorus is part of phospholipids and all nucleotides
What are these?
It is the most prevalent limiting factor in ecosystems
Main reservoir is Earth’s crust; no gaseous phase (it never enters the atmosphere – like carbon and nitrogen)

17. Phosphorus Cycle mining FERTILIZER excretion GUANO agriculture
weathering
uptake by autotrophs
uptake by autotrophs
MARINE FOOD WEBS
DISSOLVED IN OCEAN WATER
weathering
DISSOLVED IN SOILWATER, LAKES, RIVERS
LAND FOOD WEBS
death, decomposition
death, decomposition
sedimentation
setting out
leaching, runoff
uplifting over geolgic time
MARINE SEDIMENTS
ROCKS