Lesson 4 Forest Resources

Tree Harvesting Clear Cutting ~ is a form of forest harvesting that removes all trees from an area greater than 40ha. Profitable trees and undesired trees alike are cleared and the land is left uncovered.  Pg. 165

Clear Cutting Advantages Disadvantages Most rapid, economical and least dangerous form of harvesting. Disadvantages Leaves behind a poor looking landscape. Ecosystem has a very difficult time recovering. Soil is defenseless to erosion. Wildlife habitats are disturbed.

Tree Harvesting Strip Cutting ~ is a variation on clear cutting where strips of forest about 1 or 2 ha are left between the clear cut areas.  Pg. 165

Strip Cutting Advantages Disadvantages 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 Selective Cutting ~ is a form of forest harvesting that removes only mature trees and leaves the other trees in place. Immature trees, undesired species and underbrush is all left intact.  Pg. 165

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

Deforestation The removal of a forest stand by cutting and/or burning, where the land is put to a nonforest use, such as agricultural purposes, residential or industrial sites, roads, etc..

Deforestation Approx. 1/3 of the earth's land masses are covered in forest. Some values of our worlds forests are: - biodiversity - animal habitats - food for animals - air purification - water retention. Forests and trees can be used for things like: - building materials - home heat - recreation - paper. For many decades we have used the forest without regard for the sustainability of forests.  Will coming generations have a forest to rely on?  Are we allowing deforestation to occur at a rate faster than it can replace itself?

Deforestation Why are we using so much forest resource? > Some reasons for extensive deforestation include: expanding needs in agriculture urbanization mining operations hydroelectric operations “Rates of Deforestation World Wide” (pg.164)

Deforestation Latin America - clearing the forests for hydroelectric projects to provide electricity to an increasing number of people. Large scale cattle ranches and urbanization have also contributed to deforestation.

Deforestation Africa - forests are being cleared to make room for subsistence farming to support the growing population.

Deforestation Asia - A growing population means that more forest is cleared for housing and for agricultural land to feed the people.

Sustainable Forestry …is a method of harvesting or using a resource 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. 

However, as the world's population increases, the demand for forestry products increases and the demand for forestry land to be converted to housing, mining, and hydro-electricity projects. We must manage the forest, taking into consideration biodiversity, hunting, hiking, camping, habitat protection and many other things.

Sustainable Forestry From a “Systems Model” perspective: Improve what we input into forestry (replanting & seeds) Improve processes like: road construction harvesting techniques environmental protection actions reducing losses (use all of the tree) Reduce the need of output product Recycle Use of alternate building materials

Clear Cutting Controversy

Forests and Climate Seasons The type of trees and forest present in a region is determined by the climate.  Trees have adapted to climate just as animals have. Temperate regions of the world often have broad-leaf, deciduous trees to help them deal with the lack of water availability in winter. (ex: lose leaves so moisture does not freeze).  Some regions have dry seasons and they have deciduous trees even though it does not get "cold."

Seasons The needle leaf trees of the coniferous forests are adapted to deal with winter and the lack of available water. (ex: tall and narrow, grow close together, waxy coating on needles) Both the tropical regions of the world and the sub arctic regions of the world have evergreen trees.

Forests and Climate Precipitation Forests require a large amount of water.  Therefore, the amount of precipitation in a region will determine whether a forest will grow. Tropical areas with high rainfall have tropical rain forests (meaning lots of trees/vegetation). Tropical areas that have alternating rainfall amounts have Savannas because there is not enough water to support trees and a forest. 

Forests and Climate Diversity Colder regions tend to have less biodiversity while tropical regions tend to have greater biodiversity.  The same is true of trees. Tropical forests tend to be a blend of many different species, while coniferous forests tend to be "pure stands" of one type of tree. A pure stand of aspen

Case Study “Tree Harvesting in Various Ecosystems” Pg. 166 Question #9