1. Nutrients cycle… through decomposers
consumers
decomposers
producers
phosphorus
potassium
iron
carbon
nitrogen
soil
magnesium
calcium

2. What about nutrient cycles?
Energy flows through food chains but …
nutrients must be recycled to be available for the next generation
decomposers return nutrients to the soil after creatures die
fungi
bacteria
decomposers

3. HYDROLOGIC CYCLE
the continual movement of water from the Earth’s surface to the atmosphere and back to the surface again. (evaporation, condensation, precipitation, transpiration)

4. Condensation
Transpiration
Evaporation
Precipitation

5. PHOSPHOROUS CYCLE
Plants obtain phosphorous from the soil, animals obtain it by eating plants, when animals die they decompose and the phosphorus returns to the soil
Phosphorus is one of three essential nutrients for plant growth (N, P, K)

6. CARBON CYCLE The Carbon Cycle is driven mainly by TWO processes:
Photosynthesis – the process by which producers convert sunlight into a useable form of energy
Respiration – overall process by which the body gets and uses oxygen and gets rid of carbon dioxide

7. Nitrogen Cycle
The air contains 78% nitrogen! It has to be converted before it can be used by most living thing
Nitrogen fixing bacteria “fix” nitrogen so that it can be absorbed by plants.
Animals receive nitrogen by eating plants or eating organisms that consume plants.
All of the nitrogen in your body is there because of the nitrogen you obtained from other organisms!

8. Ecological Succession

9. Ecological succession
transition in species composition over time
SLOW process, can take years or decades
usually after a disturbance
Two types: primary and secondary
Mt. St. Helens

10. Primary succession
Begins with virtually lifeless area without soil, then…
Bacteria, lichens &mosses
grasses
shrubs
trees
make soil {

11. Succession of species pioneer species compete well in high sunlight
lichens & mosses
grasses
more shade tolerant species
climax forest
shade tolerant species
stable community
bushes & small trees
trees

12. The ultimate goal….Climax Community
Plant community dominated by trees
Representing final stage of natural succession for specific location
stable plant community
remains essentially unchanged in species composition as long as site remains undisturbed
birch, beech, maple, hemlock
oak, hickory, pine

13. Secondary succession
Existing community cleared, but base soil is still intact
burning releases nutrients formerly locked up in the tissues of tree
the disturbance starts the process of succession over again

14. Disturbances as natural cycle
Disturbances are often necessary for community development & survival
release nutrients
increases biodiversity
fire climax forests
increases habitats
rejuvenates community

15. Species diversity greater diversity = greater stability
Greater biodiversity offers:
more food resources
more habitats
more resilience in face of environmental change

16. The impact of reduced biodiversity
compare these communities
suburban lawn
agricultural “monoculture”
“old field”
In the early 1970's, a new corn genotype was released in the US; the "Texas male sterile" (TMS). Hybrids that contained this new characteristic had many desirable properties, and growers were excited about them, planting them over miles and miles of corn acreage in US. They were, of course, bred to be resistant to the most common corn diseases. However, they were not resistant to a previously unimportant strain of a fungal disease; the southern corn leaf blight (caused by the fungus Helminthosporium maydis). Ninety percent of the corn sowed in the US in 1970 contained the TMS trait and also shared genetic susceptibility to this pathogen. The fungus encountered all this acreage of susceptible host and wiped out one fourth of the US corn crop in 1970, a loss of over one billion dollars in production! If the corn acreage hadn't been such a monoculture, the fungus wouldn't have been able to spread as rapidly, as it would have encountered barriers of genetically resistant plants.
Irish potato famine
1970 US corn crop failure

17. Don’t blow your top!
Ask Questions!