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Forest Res.

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21 views27 pages

Forest Res.

forest

Uploaded by

amargs4774
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Forest Resources

Dr. M. CHANDRA SEKHAR


WATER & ENVIRONMENT DIVISION
NIT, WARANGAL
Forest
Resources
What is a forest?
Where do forests occur?
What are the ecological factors
associated with forest distribution?
What is a forest?
 A forest is a biological community of plants and
animals that interact in complex ways with the
nonliving environment, which includes the soil,
climate and physiography.

 Forests are usually distinguished from other


types of communities by a continuous canopy
of large trees.
 30% over the world ; 14% over Asia
Why Save forests?
 “Forests should be saved not
because they are beautiful, but only
to provide homes and jobs for
people…resources should be used
for the benefit of people who live
here now.”
Why are forests important?
 Forests affect the earth’s heat balance, cycles of
carbon and water, and soil distribution

 The history of civilizations has been associated with the


history of their forests

 Example: 8,000 years ago – agricultural civilization in


the area now known as Jordan; villages abandoned
about 1,000 years later; archeologists have concluded
that a major factor was deforestation which resulted in
soil deterioration and loss, which made farming
impossible
Uses of forests
 Climate regulation
 Rainfall
 CO2 sink
 Forest productivity
 Biodiversity
 Cultural heritage
 Recreation and tourism
Forest Regions
Around the World
 Forests cover about
30% of the earth’s
land surface

 The distribution of
forests, deserts, and
grasslands are
primarily a function of
precipitation and
temperature
Forest Regions
Around the World
 Forests occur
primarily in two
broad bands
around the earth
 Tropical areas
 Northern
hemisphere
(approx.
between 35
degrees and the
Arctic Circle)
Forest Regions
Around the World
 Trees grow on all
continents except
Antarctica.

 Trees need at least


12 inches (300mm) of
annual precipitation
and they need soil
(that is not
permanently frozen)
Rainfall
 Trees need approximately 16 inches of
annual precipitation to produce a forest.

 With less moisture, they are more widely


spaced and form woodlands
Role of Climate
 Biomes controlled by climate: extremes
of temperatures and precipitation more
significant than averages.
 Daily and seasonal cycles influence
prevailing winds
 Elevation
Vegetation Across
Environmental Gradients
 Forests can be
classified into three
major types: tropical,
temperate, and boreal
(also called taiga)

 Note similarities of
vegetation in
north/south gradient
compared to high/low
elevational gradient
Forest vs rainfall and
temp.
Forest Classification
 Primarily evergreen
 Broad-leaved evergreen (mostly warmer
climates)
 Coniferous forest (mostly cooler climates)
 Primarily deciduous
 Drought -deciduous (leaves shed in dry
season)
 Cold-deciduous (leaves shed in winter)
Deciduous forests
 Deciduous" means "falling off or out at
a certain season".
 located in the temperate zone above
the tropical forests and below the
coniferous forests
 Most of Europe, the eastern half of
North America, parts of Japan and
Asia were once covered with large
deciduous forests
 soil is very fertile & well developed
 mean temp. is around 10° C
 mean rainfall is 75-150 cm/year
 Distinct seasons
 6 month growing season
Deciduous forests
Tropical Forests
 Occur between about 23.5º N & S
latitudes
 Good rainfall >200cm/year
 Temp. warm and hot round the year
(Difference in avg. temp. < 5ºC)
 Rich nutrient cycles
 90% in living system
 50-70% plant species found
 Rapid decomposition & recycling of
organics
 Relatively thin soils
 Removed for timber, agl., mining
Fig.1. Tropical Rain forest
Fig.2. Dry tropical woodland forest
Tropical seasonal forests
 India, Asia, Australia
 Wet & dry seasons
 Hot round the year
 Evergreen to
deciduous & drought
resistant
 Nutrient rich soils &
good for agriculture
Tropical Broadleaf
Evergreen Forest: The
Rainforest
 complex biome in terms of both
structure and species diversity
 precipitation > 100 inches a year
 Vegetation: three layer of trees is
apparent
 Widely spaced trees 100 to 120 feet tall
and with umbrella-shaped canopies
 canopy of 80 foot trees
 canopy of 60 foot trees
 Shrub/sapling layer: Less than 3
percent
 Ground layer: sparse plant growth
 Less than 1 percent of the light strikes
the ground
Temperate Forests
 Distinct winter

 4-6 frost-free months


(growing season)
 Coniferous or
broadleaved evergreen
if precipitation in winter
 Broadleaved deciduous
if precipitation evenly
distributed or primarily in
summer
Boreal Forests
 Mostly coniferous
species
 Usually too cold for most
hardwood species
 Generally begin about
50º to 60º north latitude
 Winter temperatures
generally fall below
–40ºC
Coniferous forests
 Limited moisture
 Low rainfall
 Sandy soils
 Short growing season
 Thin, needle like
leaves with wax
coating to reduce
water loss
 Dominant insect
species
Commercial Forests
 Must be able to
produce at least 20
cubic feet of wood
per acre per year
(equivalent to 1.4
cubic meters of wood
per hectare per year)
Forest Areas of the World
Deforestation - reason
 Agriculture
 Dams
 Highways
 Mining
 Transmission lines
 Firewood
 Timber
 Urbanization
Deforestation - effects
 Loss of productivity
 Habitat loss
 Destruction of biodiversity
 Soil erosion
 Groundwater depletion
 Loss of soil fertility
 Climate change
 Rainfall patterns
Forest management
 Sustainable logging
 Preservation of diversity
 Nutrient conservation
 Resource extraction (latex, nuts, fibers,
fruits, animals)
 Resource generation (tourism,
recreation, hunting)
 National heritage

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