Forests- Agroforestry. Types, Fires, Management

Transcription

1 Forests- Agroforestry Types, Fires, Management

2 Types of Forests Old growth: uncut forests ( >200 yrs old)

3 Types of Forests Second growth: from sec. ecological succession, forests were cut

4 Types of Forests Tree plantations: one tree species farmed little biodiversity

5 Forest Management Types Even-Aged Management: Same age trees harvested every yrs

6 Forest Management Types Uneven-aged Management: many diff. tree species at diff. ages Selective harvesting

7 Harvesting Trees A) Selective Cutting: Mature trees in uneven aged forest are cut. reduces crowding younger trees grow natural regeneration occurs decreases soil erosion

8 Harvesting Trees Shelterwood Cutting: all mature trees are removed over 10 yr period. Seed-tree cutting: Harvest all trees except leave some seedproducing trees Clear cutting: Removes all trees at once

9 Clear Cutting If you were a timber company, why would you want to remove trees all at once? If you were an environmentalist, why would clear cutting be harmful to the environment?

10 Clear Cutting Timber Company says: 1. Increases timber yield 2. Shortens the time needed for a new stand of trees 3. Provides the maximum econ. return 4. Takes less skill (more avail. jobs for peeps) Environmentalists say: 1. Leaves large forest openings 2. No recreational value of forest 3. Reduces biodiversity 4. Leads to severe soil erosion flooding 5. Nearby trees become vulnerable to wind.

11 Logging Roads! Env. Problems: 1. Increased erosion sediment in H 2 O 2. Habitat fragmentation/loss 3. Exposure to new nonnative species and pests. 4. Truck air pollution

12 Logging Trucks (Redwoods)

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14 Case Study: Asian Long-horned Beetle From China, discovered in Brooklyn in 1996 at a plumbing warehouse. Bores holes into phloem of tree sucks out nutrients from elms, maples, and willows. Kills trees in forests tree farms must use pesticides.

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16 Surface Fires Burn only undergrowth of forest, mature trees/ animals spared. Beneficial b/c: release nutrients from leaf litter stimulate germination of fire-dependent seeds controls pathogens and non-natives

17 Surface Fires

18 Crown Fires Hot, fast fires that burn entire trees and leap from crown to crown. Occur from dead leaf litter buildup. Destroys vegetation, kills wildlife,soil erosion.

19 Ground Fires Occurs underground w/ partially decayed plant material (peat). No flames, but can smolder for a long time

20 Protect Forests From Fire? 1) Prevention: Smokey the Bear 2) Prescribed Burning: Set controlled fires to prevent leaf litter buildup 3) Presuppression: early control of fire 4) Suppression: stop fire when started

21 Smokey the Bear PSA 1975

22 Let-it-Burn Policy NFS: Fire in nat. park or forest, let it burn! Will step in if homes/buildings in danger.

23 Healthy Forests Initiative 2003 Many fires in Summer 2002 caused by overcrowding of forests 1. Thin overstocked stands 2. Clear away vegetation to create shaded fuel breaks 3. Provide $$ to reduce or eliminate hazardous fuels in National Forests, 4. Improve forest fire fighting 5. Research new methods to halt destructive insects.

24 Cut Fewer Trees? Use construction materials wisely Lay off excess packaging Stop your junk mail! (greendimes.org) Recycle paper

25 Tree-Free Fibers: Kenaf/hemp instead of trees Ex: Less herbicides (fast growing), insecticides (too fibrous for pests), and less fertilizer (nitrogen fixer).

26 Protection of Tropical Forests Slash and burn, logging Protect areas, Educate peeps, Slow pop. size Reforest and rehabilitate areas