Lecture Oct 18th

Lecture Oct 18th - 17/10/2010 1 Organization, distribution...

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Unformatted text preview: 17/10/2010 1 Organization, distribution and diversity of Life in relation with environment- Terrestrial Biomes (Oki & Kanae Science 2006) Looking at the relationship between evapotranspiration and runoff Small watershed experiments demonstrate the role of the vegetation in the relationship between ET and runoff. Hubbard Brook Ecosystem Study 17/10/2010 2 Experimental forest clearing and herbicide application reduced ET as seen in increased streamflow Vegetation plays a critical role in the hydrological balance between evapotranspiration and runoff human activity plays a critical role in determining the nature of the vegetation cover. Land-use change, vegetation management and natural vegetation change have significant effects on the balance between ET and runoff . Mountain Pine Beetle Outbreak, BC Mountain pine beetle killed forest in B.C. - 35% tree mortality 22% increase in annual flow, 56% increase in spring runoff http://www.forrex.org/publications/streamline/ISS31/streamline_vol9_no2.pdf Forest plantations may increase green water at the expense of blue water Eucalyptus, Veracel, Brazil Eucalyptus, Tazmania In Australia, plantation owners must buy a water permit, in the same way as farmers who wish to withdraw water for irrigation How does evapotranspiration work? 17/10/2010 3 Water flows in a continuous path from the soil, through plants and into the atmosphere Water moves from high water potential to lower water potential Generally, air is dry relative to the wet surfaces in the leaf, creating a large gradient in water energy potential which pulls water from the leaf. The drier the air the stronger the force. Evapo-transpiration from the leaf surface via stomates draws water through the tree. When water is limited, stomates close, stopping gas flow....
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This note was uploaded on 11/15/2010 for the course ENVR 200 taught by Professor Rhemtulla during the Fall '10 term at McGill.

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Lecture Oct 18th - 17/10/2010 1 Organization, distribution...

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