Transcript Forests
Forests-Agroforestry Types, Fires, Management Types of Forests Old growth: uncut forests ( <200 yrs old) Types of Forests Second growth: from sec. ecological succession, forests were cut Types of Forests Tree plantations: one tree species farmed little biodiversity Forest Management Types • Even-Aged Management: Same age trees harvested every 6-100 yrs Forest Management Types • Uneven-aged Management: many diff. tree species at diff. ages Selective harvesting Harvesting Trees • A) Selective Cutting: Mature trees in uneven aged forest are cut. reduces crowding younger trees grow natural regeneration occurs decreases soil erosion 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 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? 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. Logging Roads! Env. Problems: 1. Increased erosion sediment in H2O 2. Habitat fragmentation/loss 3. Exposure to new nonnative species and pests. 4. Truck air pollution Logging Trucks (Redwoods) 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. Surface Fires • Burn only undergrowth of forest, mature trees/ animals spared. • Beneficial b/c: release nutrients locked up in leaf litter into soil stimulate germination of fire-dependant seeds controls pathogens and non-natives Surface Fires 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. Ground Fires • Occurs underground w/ partially decayed plant material (peat). • No flames, but can smolder for a long time Protect Forests From Fire? 1) Prevention: Smokey the Bear 2) Prescribed Burning: Set controlled ground fires to prevent leaf litter buildup 3) Presuppression: early control of fire 4) Suppression: stop fire when started Smokey the Bear PSA 1975 Let-it-Burn Policy • USFS: If a fire starts naturally in a national forest or park, then “let it burn” until it goes out on its own. • Will step in if homes/buildings in danger. 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. Cut Fewer Trees? • Use construction materials wisely • Lay off the excess packaging • Stop your junk mail! (greendimes.org) • Recycle paper products • Reuse wooden shipping containers (ports) Tree-Free Fibers: • Make paper that does not come from trees by using tree-free fibers • Come from agricultural residues of fast growing crops (kenaf or hemp) • Kenaf needs less herbicides (fast growing), insecticides (too fibrous for pests), and less fertilizer (nitrogen fixer). Protection of Tropical Forests • Much slash and burn, logging in these forests • Protect areas, educate peeps, add subsidies that encourage sustainable forest use, reduce illegal cutting, and slow pop. Size • Reforest and rehabilitate areas that were already cleared.