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Forestry
Forests
Cover 1/3 of all land surface on earth 80% = closed canopy 20% = open canopy 70% are in North America,
Russian Federation, and South America
In USA Largest land use category (1/3) 747 million acres (500 million non
federal) Timbering in Pacific Northwest
employees 150,000 people; $7 billion per year industry
Forestry
Management of forests
Involves Planting new trees Fires
Ecological Services of Forests
1. Providing wildlife habitat
2. Carbon sinks
3. Affecting local climate patterns
4. Purifying air and water
5. Reducing soil erosion Forests serves as a watershed, absorbing and
releasing controlled amounts of water.
6. Providing energy and nutrient cycling
Old – Growth Forests
Forests that have not been seriously impacted by human activities
Rich in biodiversity Depletion of old-growth forests increases the
risk of climate change Many have trees that have high economic
value but take a long time to mature Mahogany, oak, etc.
Characteristics of Old-Growth Forests
Older and mixed-age trees Minimal signs of human activity Multilayered canopy due to tree falls Pit-and-mound topography due to trees
falling and creating new microenvironments by recycling organic material into the local environment and providing habitat
Decaying wood and ground layer that provides a rich carbon sink
Characteristics of Old-Growth Forests cont.
Healthy soil profiles Indicator species – species that can tell about
the overall health of an ecosystem Little vegetation on the forest floor due to light
being a limiting factor
Old Growth Forest22% of world’s forests
Secondary-Growth Forest63% of worlds forests
Tree Plantations
Large, managed farms with uniformly aged trees of one species
Trees may or may not be native to the environment
Trees are used for pulp or lumber Pine, spruce, eucalyptus
Harvested by clear cutting
Tree Plantations cont.
Short rotation cycles 25 - 30 years temperate zones 6 – 10 years tropics
5% of worlds forests but give 20% of current world wood production
Leading to conversion of forests to tree plantations May result in draining of wetlands and replacing
of traditional hardwoods
Tree plantation characteristics
Do not support food webs Contain little biodiversity Decaying wood is absent Use of fertilizers and pesticides can harm the
environment
Tree plantation – new stuff
New techniques leave some natural forest with in the plantation to provide a wildlife corridor
The Kyoto Protocol encourages use of tree farms as a carbon sink Carbon may be released after harvesting
Examples of Tree Farms
Tree plantationsPros Practical method for trees
that requires full or moderate sunlight to grow
Efficient and economical method
Genetically improved species of trees resist disease and grow faster
Increases economic returns on investments
Produces a high yield of timber at the lowest cost, provides jobs
Cons Reduces the recreational
value of the land Can cause soil erosion (on
steep slopes), water pollution, flooding
Causes habitat fragmentation
Reduces biodiversity Promotes monoculture
Tree plantations are prone to disease and infestation because of a lack of diversity
Forest Fires
Important ecological features Clear out old and dead trees making room for
new growth Some trees need fires to germinate – conifers
Wildfire frequency is increasing 4 times the average of 1970 – 1986 Total area burned is 7 times the previous levels
Forest Service lengthened the fire season by 78 days
Fire basics
Heat + Oxygen + Fuel source = Fire
Causes of Wildfire frequency changes
Climate change changes in annual spring and summer
temperatures Longer, warmer summers Early snow melt earlier longer dry season
Changes in fire management philosophy Old way: if there is a fire put it out NOW!
Lead to build up of flammable materials in the forest New way: if fire is NOT threatening resources, let
it burn
Types of Fires
Crown Fire: Occur in forests that have not had a burn for a long time Extremely Hot Burn Entire Trees – leap from tree top to tree top Kills wildlife Increase soil erosion Destroys structures
Types of Fires
Ground Fire: Occur underground Burn partially decayed
leaves Common in peat bogs Difficult to detect and
extinguish
Types of Fires
Surface Fire: Burns undergrowth and leaf litter Kills seedlings and small trees Spares older trees – most animals escape Advantages:
Burns away ground material, reducing larger fires Release minerals back into soil Stimulates germination of some seeds Helps keep pathogens and insects in check Allows vegetation clearing for animals
Methods of fire control
Prevention: Burning permits Closing parts of forest during
drought and high traffic Educating the public
Prescribed burning: Purposely setting controlled surface fires to thin out underbrush
Burn out: letting large fires burn themselves out
Question: Who should pay to protect these homes?
Deforestation Conversion of forests into non forested areas
Natural: caused by tsunamis, forest fires, volcanic eruptions, glaciations, desertification
Human caused: land converted to Livestock grazing Grain fields Mining Petroleum extractions Fuel wood cutting Commercial logging Tree plantations Urban sprawl
Deforestation Results Degraded environment Reduced biodiversity Reduced ecological services Threatens loss of species with specialized niches Decreases soil fertility Reduces homes for migratory birds Allows run-off into aquatic habitats Changes in local climate patterns Increases CO2 in the environment Edge effects Habitat fragmentation
Deforestation Results cont. Alters hydrological cycle Decreased amount of ground water Increased flash flooding Decreased evapotranspiration less
atmospheric moisture from rain Loss of a carbon sink Loss of tourist revenue
Causes of deforestation – schools of thought
Impoverished – believes that the major causes of deforestation is the growing number of poor people
Neoclassical – believes major cause is “open access property rights”
Political-ecological – believes major cause is entrepreneurs
Case Study: Hubbard Brook Experimental Forest
Centered on how deforestation affects nutrient cycles
Land: Forest with several watersheds each drained by a single creek, impervious bed rock close to the surface preventing seepage
Case Study: Hubbard Brook Experimental Forest
Case Study: Hubbard Brook Experimental Forest
Conclusions: An undisturbed mature forest is a dynamic
ecosystem Inflow and outflow are balanced by nutrients
entering and leaving the ecosystem Deforestation lead to an increased water run-off Nutrient loss could be limited by clearing forests
in horizontal strips
Methods to manage and harvest trees
Even-age management: tree plantations Uneven-age management: maintain a stand
of trees from seedlings to mature trees Selective cutting: specific trees are chosen
and cut High grading: cutting and removing only the
largest and best trees Shelterwood cutting: removes all mature
trees in an area in a limited time
Methods to manage and harvest trees cont.
Seed Tree cutting: majority of trees removed except for scattered, seed producing trees used to regenerate a new strand
Clear-cutting: all of the trees in an area are cut at the same time. Sometimes used to cultivate shade-intolerant tree species
Strip cutting: clear-cutting a strip of trees that follows the land contour. The corridor is then allowed to regenerate
Forest Service
Established in 1905 as agency of US Department of Agriculture
155 national forests, 22 grasslands Manages 193 million acres (about the size of
Texas) Used for: logging, farming, recreation,
hunting, fishing, oil and gas extraction, watersheds, mining, livestock grazing, farming, and conservation
Forest Service
Protects and manages natural resources Provides community assistance Cooperates with state and local
governments, forest industries, and private land owners to mange resources
Provides international assistance in formulating policy and coordinating U.S. support for protection and management of world’s resources
Relevant Laws
Wilderness Act (1964): Created the legal definition of wilderness in the US. Currently 4 agencies (National Park Service, US Forest Service, US Fish and Wildlife service, and the Bureau of Land Management) are in charge of 106 million+ acres of federal wilderness
Wild and Scenic Rivers Act (1968): Preserves and protects certain rivers with outstanding natural, cultural, and recreational values in a free-flowing condition for the enjoyment of present and future generations. Classified rivers as wild, scenic, or recreational.
Assignment:
For each of the three schools of thought briefly design a management program to deal with deforestation based on the cause of deforestation for each school of thought. Write these in your notes.