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.