PART FOUR - Forest Resources

Tree Harvesting - 1. Clear Cutting

• forest harvesting that removes all trees from an area.

• Includes desirable AND undesirable species

• the land is left uncovered.

• P. 165

1. Clear Cutting

Disadvantages – Leaves behind a

poor looking landscape.

– Ecosystem has a very difficult time recovering.

– Soil is defenseless to erosion. Especially sloped land

– Wildlife habitats are disturbed.

Advantages Most rapideconomical and least dangerous form of

harvesting.

Tree Harvesting – 1. Clear Cutting

Tree Harvesting – 2. Strip Cuttinga variation on clear cutting where strips of forest about 1 or 2 ha are left between the clear cut areas. 

2. Strip Cutting

Advantages Less ecological disruption than clear cutting. Soil erosion is less severe. Forest can regenerate naturally without human help.

Disadvantages Requires a larger section of forest to produce the same amount of yield. More disruption to the ecosystem. Ex: extra roads.

Tree Harvesting – 3. Selective Cutting

• forest harvesting that removes only mature trees and leaves the other trees in place. 

• Immature trees, undesired species and underbrush is all left intact. 

3. Selective Cutting

Disadvantages Most expensive method. Yields are lower. Care must be taken to avoid damaging unharvested trees. Roads must be maintained longer to keep harvesting

mature trees.

Advantages Leaves the biggest portion of the forest intact. Causes the least ecological disruption.

Deforestation – p. 163• The removal of a forest by cutting and/or burning,

• the land is put to a non-forest use…

• Ex. farms, grazing pastures residential or industrial sites, roads, etc..

Deforestation

Some values of our worlds forests are:

biodiversity medicine/pharmaceuticals animal habitats food for animals air purification water retention soil maintenance

• Forests and trees can be used for things like:

- building materials- home heat- recreation - paper.

Approx. 1/3 of the earth's land masses are covered in forest.

Importance of the Forests

• Forests prevent soil erosion through the use of their roots (roots hold the soil together).

• Prevent flooding… Trees take up much of the water.

• Prevent soil from drying up… SHADE soil and forest floor from warm temps.

• Wind break that prevents wind erosion… Wind would blow the soil away…epsecially dry soil.

Importance of the Forests

• Forests also add decaying material to the soil (humus content) otherwise the soil would have less to no nutrients.

• Help filtrate the water.

• Recycles air…CO2 into O2.

• Base of the food chain for many ecosystems.

Extensive Deforestation – The Reasons!?!?

• Expanding needs in agriculture (#1 reason)

• Urbanization

• Mining operations

• Hydroelectric operations - flooding the land

• Logging, lumber, building materials

Between the TROPICS….

“Rates of Deforestation World Wide” (pg.164)

Deforestation - Latin America• Developing nations of the world.

• forests cleared or lost due to hydroelectric projects to provide electricity to an increasing number of people.

• Large scale cattle ranches and urbanization have also contributed to deforestation.

• The cost of “modernization”!!!!

Deforestation - Latin America

Deforestation - Africa • Poorer, under-developed region of the world.

• making room for subsistence farming to support the growing & hungry population.

Deforestation – Asia• A growing population!!!• The forests are cleared for housing and for agricultural land to feed the people.

Sustainable Forestry• Sustainable means to manage or

maintain something so that it remains and provides benefits over the LONG term.

• Sustainable forestry… is a method of harvesting AND using the forests so that the resource is not depleted or permanently damaged.

FACT• If we cut trees faster than they

grow back, we will run out of trees... NO KIDDING!!!

Jeopardizing “Sustainable forests!”

WORLD POPULATION INCREASES CAUSES:

• The demand for forestry products increases (It is a RESOURCE with value)

• the demand for forestry land to be converted to other uses…housing, mining, and hydro-electricity projects, etc..

Sustainable Forestry…HOW??

From a “Systems Model” perspective:

1. Improve what we input into forestry (replanting & seeds)

2. Improve processes like: o road construction o harvesting techniques o environmental protection actions o reducing losses (use all of the tree)

3. Reduce the need of output product Or even Maximize use.o Recycle, use all parts, reduce wastage etc..o Use of alternate building materials

Clear Cutting Controversy

(handout)

Forests and Climate

• Warm/hot & wet, 365 days of growth!! = more diversity, largest & tallest trees, usually broad-leaved trees. (Tropical Rain Forest)

• Driest or coldest = less diversity, fewer, shorter and smaller trees or even grasses usually specially adapted. (Tundra, Desert or Grasslands)

• In between!!! (US!)…temperate regions, winter & summer seasons, mixed forests (broad-leaved & coniferous trees)

Case Study• “Tree Harvesting in Various

Ecosystems”• Pg. 166• Question #9