Our World

Notes for 2-7-06

II. Human Impacts on Plants and Animals: The Glabalization of Nature
A. Bioregion: An assemblage of local plants and animals covering a large area (tropical rainforest or grassland)
1. Includes naturally occuring flora and fauna
2. Shaped by our domestication- and modification- of these plants and animals
3. Today bioregions may be home to multinational conglomerates as well as to local plants, animals, and peoples
B. Tropical Forests and Savannas
-Mostly found in equatorial climate zones
-Covers around 7% of the world's land area
-Three layered canopy
-As one moves polewards, distinct dry season forms and tropical forest becomes more open
- Further poleward, grassland and savanna replace forest
C. Deforestation of the tropics
-Annually, an area of tropical forest the size of Wisconsin is denuded
~Land cleared for wood sale, for cattle grazing and for settlement purposes
~Natives lose their homes
D. Deserts and Grasslands
-Large areas of arid and semi-arid climate that lie poleward of the tropics
-Comprise 1/3 of the Earth's land surface
~Desert: Areas recieve less than 10 inches of rain a year
~Prarie: North American grassland
~Steppe: Shorter, less dense grassland found in Russia and SW Asia
-Desertification: The spread of desert-like conditions
~Caused by poor agricultural practices on marginal land, overgrazing, build-up of salts and soil from irrigation
E. Temperate Forests
-Large tracts of forests found in middle and high latitude (near poles)
-Two major tree types dominate
~Conifers of evergreens (pine, spruce, fir)
~Deciduous trees that lose leaves in winter
-Forests cleared for agriculture
-Commercial logging places pressure on forests

posted by Anonymous @ 2/08/2006 10:30:00 PM