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Lecture 6

BIOC63Fall2013 Lecture 6 Notes.docx

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Biological Sciences
Karen Williams

1 BIOC63Fall2013 Lecture 6 Notes: Habitat Modification  Habitat destruction o Land use is the largest threat to biodiversity o The destruction is in full swing in the tropics  Has already occurred in N. America o Yellow  red = high biodiversity o Highest biodiversity is in the tropics  this is also the same areas that are now being destroyed Old growth forest destruction o o Before arrival of humans, pretty much all of GB was covered in forest th o Now, not so much  almost all of it is gone (by the middle of the 19 century) o This also happenned in NA but it happenned much much faster o Started when Europeans started to settle in on a larger scale o Wherever there was enough precipitation, we did have a lot of forest  S Ont would be almost 100% forest o 200 years later, there is thinning o By the beginning of th 20 century, most of the forest was gone(down to 4%, europeans cut don 96%) o Old growth forest = original vegetation Global loss of terrestrial habitats o 1 2 o By 1950 we removed between 60 and 70 % of temperatare forest steppe and woodland by 1950 o Few are prone to be still impacted in the future: tropical and subtropical broadleaf, grasslands and savannas, coniferous forests and moist broadleaf forest o We have a negative loss in temperate forest project by 2050  forest growing back where soil was not good for agriculture so farmers le tit and so the forest was able to regenerate Destruction of Terrestrial wetlands o o 6 states lost more than 95% of wetlands including their ecosystem services  due to construction, agriculture etc. Destruction of Mangroves  Extremely important for fish nesting sites  50% deduction in mangroves worldwide so far  Fish that spend majority of life in ocean, but come back to these places to pawn the young and etc.  Shrimp hatcheries are the number 1 reason why we are loosing the mangroves Habitat fragmentation  Wildlife affected by things like roads, in the park  used to be all forest  even preserved provincial parks are still affected due to roads running through the park o i.e. wildlife is affected Fragment size vs. biodiversity o remaining fragments = island effect  the smaller the island, the fewer the number of species  i.e. island/fragment size and diversity are directly proportional  i.e. the bigger the forest the higher the dung beetle productivity  Diversity in fragments vs. ecosystem function o number of plant species and functional groups alter plant biomass in grasslands 2 3 o o number of species is influenced by habitat size, and ecosystem functioning is influenced by the number of species present in the ecosystem o the more species in an ecosystem, the better and more productive it is  productivity increases till it reaches a max level where it levels off after  diversity and ecosystem are directly proportional
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