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Forests and their Interactions

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1 Forests and their Interactions
AP Environmental Science

2 Types of Forests Any area where trees cover more than 10% of land.
Includes: open savannas - < 20% ground cover Closed canopy forest – tree crowns overlap to cover most of the ground. Primary forests: composed primarily of native species

3 Reason why old forests are important?
O.F. contain unique biological features w/: large live & dead trees a large variety of vegetation, insects and animals species. Often home to rare species, threatened species and endangered species of plants and animals, making them ecologically significant.


5 Types of Forests-Old Growth
Other names include: Virgin forests Primary forests Ancient forests Primevil forests


7 Old Growth Forests

8 New Growth Forests

9 New Growth forests

10 Deforestation & Consequences
Cause of deforestation? Consequences!! Logging industry Cattle ranching Farming Biofuel production Food production (ie. palm oil) Erosion Water Runoff Excess CO2 Loss of biodiversity Loss of cultural & historic values

11 Forest Canopies Upper canopy Mid-canopy Lower Canopy

12 Forest Fires Forest Fire Management Nova Fires by Month 2000

13 Forest Fires-Hot Question
In Mediterranean climates like portions of California, a wetter than normal winter often leads to greater severity of fires following summer. This paradox occurs because increased rain leads to… A. Greater accumulation of chaparral biomass B. Higher pollination of annual flowers C. Greater recreational use of parklands D. Greater erosion & damage to access roads E. Decreased summer rainfall

14 Forest Protection Legislation
1. Debt for Nature Swap Roadless Rule – Clinton Administration Northwest Forest Plan to regulate harvesting on about 9.9 million ha of federal lands in Oregon, Washing and northern California.

15 Question to ponder? The largest area of old-growth forest in the United States is located in: Alaska B. Montana California North Carolina Michigan



18 Forest and Competition
There are several species interactions within an ecosystem: 1. Competitive Exclusion Principle 2. Resource Partitioning 3. Ecological Niche

19 Competition Between Species
This type of interspecific competition: may occur when 2 or more species in community use similar resources & those resources are in short supply OR - may limit the population growth of the competing species Intraspecific Interactions Relationships within the same species

20 1. 1. Competitive Exclusion Principle
Experiment #1: Russian ecologist G. F. Gause studied the effects of interspecific competition in two closely related species of protists called Paramecium. What do these results tell you about the interaction of these 2 species? Separate cultures Combined cultures P. aurelia P. caudatum

21 From his research, Gause concluded that two species so similar that they compete for the same limiting resources cannot coexist in the same place for any length of time. One species will always be more efficient and adaptable: ….in getting food ….in reproducing Ecologists called this concept the competitive exclusion principle

22 Ecological Niche: a. Sum total of a species’ use of biotic and abiotic resources in its environ & b. A species’ habitat & it’s job (ex. Forest / producer) • We can now restate the competitive exclusion principle as follows: Two species cannot coexist in a community if their niches are identical.

23 Resource Partitioning-
Experiment #1: Explain this example of resource partitioning. How have the different species adapted to their competition? A. ricordii A. ricordii A. insolitus A. distichus A. insolitus A. aliniger A. christophei A. distichus A. distichus A. christophei A. cybotes A. cybotes A. etheridgei A. etheridgei A. insolitus Figure 19.7

24 2. Resource Partitioning
There are two possible outcomes of competing species w/ identical niches (not just living in the same area) 1. Extinction of one species 2. Evolution of one species to use a different set of resources Resource partitioning is the differentiation of niches that enables similar species to coexist in a community.

25 Reproductive Potential
…Is an organism’s ability to grow at the fastest rate. (To replenish the species—innate!)

R-selected Hint: Rapid Repro Early reproduction Short life span Hi mortality Little/no parental care Large # of offspring produced 2. K-selected Hint: Longer Repro Late reproduction Long life span Low mortality High parental care Small # of offspring produced


28 Reproduction Connection
Which of the following is generally true of a K-strategist species? A. They reach sexual maturity faster. B. They have more young. C. They are likely to be invasive species. D. They have longer life spans. E. Their populations cycles are more rapid.

29 The Complexity of Community Networks
The interrelatedness of interactions between species makes communities complex Recruitment Release of volatile attractants Chemical in saliva Wounding Detection by plant Figure 19.17

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