Forestry Notes
Ecosystem-based forest management
Goal: to harverst resources while minimizing effects on the rest of the ecosystem Ecologically sensitive areas are carefukky monitored and protected; resources are harvester selectively Ecosystems are complex, so choosing which areas to protect and which to harvest is a challenge Forests vary in their make-up age, and origins Old growth or primary forest 36% of world’s forest Second-growth forest 60% of worlds forest Tree plantations, tree farm or commercial forest 4% of world’s forest May supply most of the industrial wood in the forest Ecological value: Provide habitat for organisms Source of biodiversity Prevent erosion Purify water Store carbon, release oxygen Economic value: Timber for lumber and fuel Source of food Raw material for many medicines Timber Harvesting Methods 4 methods: Clear-cutting, seed-tree or shelterwood approach, and selection system May result in even-aged or uneven-aged regrowth Even-aged regrowth tends to be less biodiverse than uneven-aged regrowth. Clear Cutting Involes cutting down all trees in a region, resulting in even-aged stands of regrowth Change abiotic conditions in the area, including light penetration, precipitation, wind, and temperature Benefit: cost efficient Cost: entire communities usually displaced of destroyed; causes soil erosion Seed- tree and shelterwood approaches Seed-tree: Small numbers of mature, healthy trees are left standing, to reseed the area. Shelterwood: Involves leaving a few mature trees standing to provide shelter for seedlings Benefit: Less damaging than clear-cutting Cost: As with clear-cutting, leads to mostly even-aged regrowth Selection system Relatively few trees are cut at once under a selection system. Selection can involve widely spaced single trees or groups. Benefits: More biodiverse, uneven-aged growth Less overall environmental damage Costs: Machinery disturbs forest interior. Expensive process More dangerous for loggers Unsustianable logging is a major threat to forest ecosystem Increased erosion Sediment runoff into waterways Habitat fragmentation Loss of biodiversity Deforestation Unlike timber harvesting, deforestation replaces forested areas with some other land use, such as commercial or residential property. Deforestation in tropical and arid regions has the most negative effects due to loss of biodiversity and desertification risk respectively. Globally, deforestation adds CO2 to Earth’s atmosphere |
Deforestation in developing nations
Timber from old-growth tropical rain forests is a source of income in developing nations. Advanced technology enables deforestation to occur far faster than it has in the United States. Deforestation of tropical rain forests has an enormously negative effect on global species diversity. US National Forest The national forest system was established in 1905. Originally set aside to grow trees for timber and to protect watersheds Today, managed by the U.S. Forest Service, for timber, recreation, wildlife habitat, and mining National Forest Management Act (1976) Requires that renewable resource management plans be made for each national forest Plans are required to be consistent with the principles of multiple use and maximum sustainable yield. Logging has declined in national forests since passage of the Act, but policies are vulnerable to political influence Logging on Private Land Most logging in the U.S. takes place on privately owned tree plantations. A tree plantation is typically an even-aged monoculture with little habitat variety or biodiversity. Use of plantations for timber protects National Forests from being logged. Fire, Insects, and Climate Change can threaten Forest Ecosystems Surface fires Usually burn leaf litter and undergrowth May provide food in the form of vegetation that sprouts after fire Crown fires Extremely hot: burns whole trees Kill wildlife Increase soil erosion Fire Policies Fire Suppression: Negative effects on ecosystems that depend on fire Fuel for future fires accumulates (limbs, sticks, and leaf litter). Suppressing small fires increases likelihood of larger, dangerous fires. Prescribed Burns: Carefully controlled burning helps to reduce fuel buildup and to restore ecosystems. Rarely burn out of control, but occasional accidents frighten the public. Fire, Insects, and Climate Change can threaten Forest Ecosystems Introduction of foreign diseases and insects Accidental Deliberate Global warming Rising temperatures Trees more susceptible to diseases and pests Drier forests: more fires More greenhouse gases Healthy Forest Restoration Act (2003) Encourages prescribed burns Promotes salvage logging—removal of small trees, underbrush, and snags by timber companies Seen as harmful by many scientists and environmental advocates Salvage logging can slow forest regrowth, promotes wildfires, and destroys snags—habitat for wildlife. Sustainable Forestry Products Independent organizations certify that wood products are produced sustainably. Forest Stewardship Council (FSC) has the strictest standards and most widely accepted certification process. Certified wood costs more to produce, but will be supplied by timber companies if there is demand. |