Effects of the common cormorant,phalacrocorax carbo,on evergreen forests in two nest sites at Lake Biwa,Japan |
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Authors: | Akira Ishida |
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Institution: | (1) Laboratory of Forest Protection, School of Agricultural Sciences, Nagoya University, 464-01 Nagoya, Japan |
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Abstract: | The effects of the habitation of the common cormorant on vegetation were evaluated in two colonies in Lake Biwa, central Japan.
The state of the vegetation of each colony was classified arbitrarily into the following three types according to the appearance
of the tree, shrub and herb layers; dense tree layer (Type 1), sparse tree layer and herb layer (Type 2), and sparse tree
layer with dense herb layer (Type 3). The density of cormorant nesting was almost similar among the three types, except for
part of Type 2. Trees, especially large ones on which cormorants nested, were found to be heavily damaged, and there were
few seedlings and saplings found under the canopy trees.Chamaecyparis obtusa andCryptomeria japonica were more heavily damaged than other evergreen and deciduous trees. In the herb layer, only a few species such asReynoutria japonica orPhytolacca americana were abundant. These results suggest that the habitation of cormorants could simplify the structure and the species composition
of forests. |
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Keywords: | bird colony common cormorant evergreen forest tree decline vegetation |
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