Human Activities That Cause Habitat Loss

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Urbanization Among the many human activities that cause habitat loss (Czech et al. 2000), urban development accounts for some of the greatest local extinction rates and frequently eliminates the large majority of native species (Vale and Vale 1976, Luniak 1994, Kowarik 1995,Marzluff 2001). Also, urbanization is often more continous than other types of habitat loss. Throughout much of New England, for example, ecological succession is restoring forest habitat lost from farming and logging, whereas most urbanized areas in that region continues to grow and threaten other local ecosystems (Stein et al. 2000). Another great conservation challenge of urban growth is that it replaces the native species that are lost with widespread “weedy” nonnative species that are in most cases not useful. This replacement makes the process of biotic homogenization that threatens to reduce the biological uniqueness of local ecosystems (Blair 2001). 2.3 Exploitation Many tropical timbers have become exceedingly scarce because of overexploitation and thus face economic extinction (Oldfield 1988). Few ones are also in danger of biological extinction (Ledig.,1992). Some are overexploited and have been completely logged out of major parts of their native ranges (Gentry and Vasquez., 1988). 2.4 Fragmentation Fragmentation of the natural environment by agriculture and urban development has two major impacts; it subdivides populations into small units and it imposes barriers to migration
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