Ecosystem Approach: Variation of Forests

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Chapter 9: Ecosystem Approach

Variation of Forests in Their Age, Makeup, and Origins

A. 2 Major Types of Natural Forests
1. Old-growth/ Primary
-uncut/ regenerated forest that has not been seriously disturbed by human activities/ natural disasters for 200 years or more - reservoirs of biodiversity (provide ecological niches for a variety of wildlife species) 2. Second- growth

- stand of trees resulting from secondary ecological succession

B. Tree Plantation/ Tree Farm/ Commercial Forest
-managed forest containing one or two species of trees that are all of the same age -could supply most of wood
-less biologically diverse ( one or two only)
- less sustainable

Economic and Ecological Services of Forest
-Remove Carbon dioxide through photosynthesis
- Provide habitats of 2/3 of Earth’s terrestrial species
- Shelter for humans

Threats to Forest Ecosystems

I. Unsustainable Logging
A. 3 Ways of Harvesting Trees

1. Selective Cutting
- intermediate- aged or mature trees in forests are cut singly or in small groups 2.Clear Cutting
- most efficient
- cuts all trees
3. Strip Cutting
- involves clear- cutting a strip of trees along the contour of the land within a corridor narrow enough to allow natural forest regeneration within a few years

II. Forest Fires

A. 2 Types of Fires

1. Surface fires
-usually burn only undergrowth and leaf litter on the forest floor 2. Crown fire
- extremely hot fire that leaps from treetop to treetop, burning whole trees. - usually occur in forests that have not experienced surface fires for several decades, a situation that allows dead wood, leaves and other flammable ground litter to accumulate

III. Deforestation
* Is the temporary or permanent removal of large expanses of forests for agriculture, settlements, or other uses. Rapid Disappearance of Tropical Forests

Tropical Forests
* Cover about 6% of Earth’s land area
* Being cut rapidly in parts of Africa, Southeast Asia, and Suth America * Habitat of almost half of the world’s known species of terrestrial plants, animals, and insects.

Causes of Tropical Deforestation:
A. Underlying Causes
-Population growth and poverty
-push subsistence farmers and the landless poor into tropical forests B. Direct Causes
- Government Subsidies
-Plantation Creation

How to Manage and Sustain Forests?

I. Forest Fire Management Improvement
* To set small contained surface fires to remove flammable small trees and underbrush in highest- risk forest areas * To allow some fires on public lands to burn, thereby removing flammable underbrush and smaller trees, as long as the fires do not threaten human structures and life * To protect houses and other buildings in fire- prone areas by thinning trees and other vegetation in a zone of 60 meters around them and eliminating the use of highly flammable construction materials such as wood shingles * To thin forest areas that are vulnerable to fire by clearing away small fire- prone trees and underbrush under careful environmental controls

II Reduction of The Demand for Harvested Trees
III. Ways to Reduce Tropical Deforestation
A. Debt- for nature Swap
-makes it financially attractive for countries to protect their tropical forests -participating countries act as custodians of protected forest reserves in return for foreign aid or debt relief B. Conservation Concessions

-governments or private conservation organizations pay nations for agreeing to preserve their natural resources. C. Use Substitutes

How Should We Manage and Sustain Grasslands?

I. Some Rangelands are Overgrazed

Grasslands
* Are the ecosystems most widely used and altered by human activities Rangelands
* Unfenced grasslands in temperate and tropical climates that supply forage, or vegetation for grazing (grass eating) and browsing (shrub eating) animals Pastures
* Managed grasslands or fenced meadows often planted with domesticated grasses or other...
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