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
  

land reforms

• land reform: a policy to reach more equitable ownership of an area of land
  

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