deforestation
- deforestation: the destruction of forests
- humans alter, fragment, and eliminate forests
- common causes of deforestation
- convert the land for agricultural use (eg. cattle, crops)
- form new settlements as population grows
- logging for lumber and firewood
- ~2 billion people currently rely on firewood for cooking and heating, though cooking on an open fire is dangerous and inefficient, releasing carbon monoxide and CO2 into the atmosphere
- extraction of minerals
- increasing forest fires due to climate change
- slash-and-burn agriculture
- trees are cut down, allowed to dry, and burned to make the soil nutrient-rich, and making the land available for crops or cattle
- may be a form of subsistence agriculture (farm for self-subsistence)
slowing or stopping deforestation
effects of deforestation
- loss of cover exposes the forest floor (erosion)
- as less CO2 is captured, more is released into the atmosphere (climate change)
- less waste recycling, water purification, and pollution control
- loss of biodiversity
- loss of language and cultural/religious practices (cultural extinction)
guiding principle: sustainability
- sustainability: the principle of meeting present-day needs without compromising the ability of future generations to meet their needs
- maximum sustainable yield: the act of acquiring the maximum amount of a resource (eg. wood) without depleting the resource
- ecological pricing: the idea that the costs of the goods we use should take into account their environmental costs
- putting a price on nature
- protecting/creating forest land is the process of setting aside public land to grow trees
- national forests are multi-use lands with an emphasis on balancing recreation, grazing, timber, watershed protection, wildlife and fish, and wilderness
- national forests are not national parks
debt for nature swaps
- many biodiversity hotspots are located in developing countries, which usually have large foreign debt
- debt-for-nature swap: an agreement between a country and its debtor(s) in which part of the country’s debt is forgiven in exchange for a commitment to protect part of its land \n
land reforms
- land reform: a policy to reach more equitable ownership of an area of land \n
individual actions
- reduce/reuse/recycle
- conserve wood and buy products made from sustainably harvested wood
- buy non-timber forest products like Brazil nuts
- leave nonexistent or small footprints if spending time in forests
ecological succession
ecological succession
- the types of species present in a community are usually changing in response to environmental conditions
- ecological succession: the process of gradual change in the composition and function of a community
primary succession: the community is developing in a site previously unoccupied by living organisms, a barren habitat with very little topsoil
- pioneer species → intermediate species → climax community
- process of primary succession
- eg. lichens are pioneer species and contribute to the formation of the soil
- soil formation: biological factors interact with physical and chemical factors to develop the soil
- one such biological factor is lichens
secondary succession: begins in an area where natural vegetation has been disturbed, but soil remains
- eg. abandoned farmland, cut forest
types of forests
- primary forest/old-growth forest: a forest that has not been disturbed for an extended period of time (200+ years)
- usually uneven-aged — trees of different ages and heights
- have many different species, few invasive species
- secondary forest: a forest that has regrown after some human disturbance, results of secondary succession
- may be even-aged, if all trees were planted at the same time
- may lack very old and very tall trees
- usually have less species diversity
- tree plantation/tree farm: an area of trees managed by humans, only containing one or very few species that are commercially valuable (monoculture forestry)
- usually even-aged
- placed in regular rows
global distribution of forests
- 70% ⇒ secondary growth
- 25% ⇒ primary growth
- 5% ⇒ tree plantations
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