Please enable JavaScript.
Coggle requires JavaScript to display documents.
5.4 forest ecosystems and deforestation (Forest ecosystems (Natural and…
5.4 forest ecosystems and deforestation
Forest ecosystems
Natural and planted forests occupy about 31% of earths surface
russia, Brazil, Canada, the US, and china are the 5 countries with the largest forest areas.
forests provide humans with various resources
biofuel: Wood for burning- cooking and heating
Industrial wood: Wood for construction and paper
Medicines: Traditional medicines that come from forest plants are used by 80% of humans
The ecosystem and economic services that forests provide are much more valuable that the resources they provide
Ecosystem services essential for human survival and health
Ecosystem services essential for economies
forests vary in age and structure.
Scientists divide forests into major types based on their age and structure
old growth/primary forest
Second growth forest
Tree plantation/tree farm/commercial farm
old growth are uncut or regrown forests that haven't been disturbed for 200+ years
They are reservoirs of biodiversity
Second growth forests have younger tress. They develop after trees in an area have been removed by human activity or natural disasters
deforestation
Deforestation is the temporary or permanent removal of large expanses of forest for agriculture, settlements, etc.
During the past 8000 yrs deforestation has eliminated half of the earth's old growth forests
Deforestation causes:
Water pollution and soil degradation from erosion, acceleration of flooding, local extinction of specialist species, habitat loss for native and migrating species and release of co2 and loss of co2 absorption
Forest tree harvesting
Clear cutting is the most common method of harvesting trees
Reducing tree cover allows moisture in air and soil to evaporate and be blown away. It changes local climate and soil becomes dry and exposed. This might cause for forests to not be able to grow back again
Habitat fragmentation
Fragmentation is when a large area, such as a forest or natural grassland is divided into smaller, isolated patches or habitat lands
fragmentation can be as bad as a complete destruction
Indian tigers, black rhino, African elephant, and Asian or Indian elephant have all suffered from habitat destruction and fragmentation
Tropical forest deforestation
Tropical forests are essential to the planet. They absorb and store 1/3 of the world's carbon emissions as part of the carbon cycle.
More than half of the worlds known species of plants, animals and insects live in tropical forests
500000 football fields of tropical forest are destroyed every week
forest fires are increasing in frequency and severity
increase in fires due to
Climate change: Increase in temp= longer dryer summers
Residential expansion into forest areas
Suppression of smaller fires
Fragmentation
surface fires usually only burn undergrowth and leaf litter
crown fires are large hot fires that leap from treetop to treetop