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Final Report

Initial | Fragmentation | Amphibians | Bats | Monitoring | SIVAM

The Effects of Fragmentation

The edge effects present in areas of fragmented forest are extremely detrimental to the area of forest they contain. It leaves them more susceptible to external threats, and leaves the areas of forest left too small to support a healthy biosystem. The best compromise we can make is to give suggestions about how to make fragmentation more "healthy." We suggest you do that by trying to surround fragmented areas with secondary forest growth, or by trying to use controlled logging around the edges of a particularly large chunk of rainforest.


Following information taken from:
    Soule, Michael; Orians, Gordan.  Conservation Biology.  Washington: Island Press, 2001.

    There was a forest fragmentation experiment in Manaus Brazil, here are some examples of the results:
        - overall reduction in biomass
        - reduction of overstory vegetation
        - increase in understory vegetation
        - fragment edges were hotter, drier, windier
            - high mortality of trees at edges
            - higher leaf-fall rate near edges
        - air temperature, litter biomass and moisture, and percentage of ground covered with twigs were correlated with the
               distance from the edges
        - beetle species composition changed both with decreasing distance from the edge, and with decreasing fragment size

Critical Area due to Fragmentation

There is no critical area.

In the Lovejoy experiment at Manuas, documented effects were:

  • 2 years - Large flocks of mixed species birds disappear in both the 1 and 10 hectare square plots
  • 10 years- After 10 years, all animals with very large ranges (army ants, bird flocks that follow army ants, and animals like capuchin monkeys) had completely disappeared from even a 100 hectare square.

    How to Mitigate the Effects of Fragmentation :

    Fragmented areas surrounded by secondary forest growth were healthier than areas surrounded by shrub or grass.