4015_tutorial_8-1

4015_tutorial_8-1 - Habitat Fragmentation Habitat Fragmentation Habitat fragmentation is due to anthropogenic disturbance oto of a fragmented

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Habitat Fragmentation
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oto of a fragmented Valdivian forest in Chile from: www.tncfire.org Habitat Fragmentation Habitat fragmentation is due to anthropogenic disturbance
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Anthropogenic Disturbance –removes biomass and creates heterogeneity or patchiness
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mages from Deutschman et al . (1997); www.sciencemag.org Natural disturbance regime 500 yr 1000 yr Green = Eastern hemlock Purple = American beech Red = Red maple Yellow = Yellow birch Nature is Inherently “Patchy”
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500 yr 1000 yr mages from Deutschman et al . (1997); www.sciencemag.org Natural disturbance regime Anthropogenic clearcut Nature is Inherently “Patchy”
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Landscapes are naturally made up of patches and mosaics of vegetation
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Metapopulation  (a population of populations) – local  populations linked by occasional interbreeding, need corridors to  do this
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Corridor
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Nature is inherently “patchy,” but anthropogenic disturbance results in landscapes different from (and less hospitable than) those resulting from natural causes
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Fragmentation reduces the  extent and connectivity  of habitats Nature is Inherently “Patchy”
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Fragmentation reduces the extent and connectivity of habitats
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Fragmented landscapes typically have more contrast between adjacent patches
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Fragmented landscapes typically have more contrast between adjacent patches
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Features of fragmented landscapes ( e.g. , roads and  dams) 
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oto of a fragmented Valdivian forest in Chile from: www.tncfire.org (2) A change in habitat configuration ; remaining patches are smaller and more isolated than in the original configuration with two components: (1) A reduction in area of the habitat type Habitat Fragmentation Habitat fragmentation is an anthropogenic disturbance
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Extinction Debt (due to fragmentation): Prediction of future extinction of species due to  events in the past.  Extinction debt occurs due to time delay between  impacts on a species, such as habitat  fragmentation, and the species' ultimate  disappearance.  For instance, long-lived trees may survive for  many years even after reproduction of new trees  has become impossible, and thus they may be  committed to extinction. 
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Initial Exclusion  –  elimination of species  when habitat is  fragmented Back in 1978, two ecologists named Alwyn Gentry and  Caraway Dodson documented 90 species of plants unique  to the Centinela ridge in Ecuador. By the mid 1980s,  farmers had cleared the ridge of the unique life to make  space for crops. Those species are now lost forever.
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The Centinela Ridge is in a 20 square kilometer cloud forest in the foothills  of the Andes. Among the plants were 38 endemic species, many of which  were unusually dark leafed.  The two scientists found a total of 90 related  plants growing under the forest canopy with epiphytic plants, such as 
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This note was uploaded on 07/07/2011 for the course BIOL 4015 taught by Professor Prowell during the Summer '08 term at LSU.

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4015_tutorial_8-1 - Habitat Fragmentation Habitat Fragmentation Habitat fragmentation is due to anthropogenic disturbance oto of a fragmented

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