GEOG 4400: Resource Use

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22 Φεβ 2014 (πριν από 3 χρόνια και 5 μήνες)

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GEOG 4400: Resource Use

Lecture 7

Biota

“Any fool can destroy trees. They
cannot defend themselves or run
away.” John Muir



The World’s Forests


Where


How much

Where


How much


Change

Change


Deforestation


10.1 billion acres of forest in the world (31%
of land cover)


50% of tropical forests cleared (2/3 in SE Asia)


40
-
50 million acres per year


150 acres per minute


Football field per second

Deforestation


agriculture


local needs


export crops


wood supply


fuelwood

Causes of Deforestation


Poverty


Fuelwood

crisis

Causes of change


Population growth


Capitalism


Inappropriate technology


Inappropriate government policies


Forest concessions


Underpricing


Removal of indigenous population


Ecological collapse


Tragedy of the commons

Forest resources


Hardwood


Coffee


Spices


Nuts


Cacao (chocolate)


Latex


Dye


Medicines


Agriculture (rice, wheat, corn)


50
-
90% of all biological diversity is in forests


Potential loss of 5
-
15% of world’s species from 1990
-
2000


50
-
150 species per day

Uses of forest products


Traditional


Industrial


Services

Types of harvest


Shelterwood


Selective


Clear
-
cutting


Biomass harvesting

Effects of harvesting


Roads (340,000 miles = 10x interstate highway
system)


Compaction from heavy equipment


Erosion


Nutrient removal


Water regime alteration


Stream conversion

Trends in forestry


Industrial wood supply


Plantations


Global trade


Fuelwood


Services

Other problems:


Greenhouse effect

Forest structure


Fire


Good: release nutrients, remove old sick trees, allow
light, burn off fuel


Bad: consume biomass, increase in runoff,
sedimentation


Fire frequency
-

return interval


Types: ground, surface, crown, firestorm


Disease:
fusiform

rust, dwarf mistletoe, root
diseases


Insects: spruce budworm, gypsy moth, pine
beetle

Reforestation


Causes of change


Population growth


Capitalism


Inappropriate technology


Inappropriate government policies


Forest concessions


Underpricing


Removal of indigenous population


Ecological collapse


Tragedy of the commons

Reforestation


Natural regeneration/ seed tree


Artificial seeding


Seedling plantings


Plantation conversion (forest??)

Sustained Yield


Harvesting of a species at a rate equal to its
reproduction or maturation

Multiple Use Sustained Yield Act of
1960


recognize other uses of national forests


balanced management approach


timber


watershed maintenance


wildlife habitat


recreation

National Forest Management Act of
1976


limited size of
clearcuts


protect riparian areas


regulation of rate of harvest


wilderness reviews (RARE studies)

Debt for Nature swaps


Wildlife


Extinction


Genetic Material


Exotic Invasions