Changes in Khasi pine (Pinus kesiya Royle ex Gordon) tree stands affected by Dimorphic Egret Egretta dimorpha colony at Madagascar

Abstract

Establishing plantations of quick growing introduced trees, combined with effect of a bird colony, affect habitat conditions. This causes alterations in spatial structure of a phytocenosis, its species composition and size of plants in herb layer. In the studied Khasi pine (PinuskesiyaRoyle ex Gordon) stand in central Madagascar the shrub layer was found only under egrets' nests, while it did not occur outside the colony. We observed four times higher number of species, and much greater coverage of shrub and herb layers in the colony than outside, which reflects the increased soil trophy in the colony. One of the common species of herb layer was Commelinaafricana. Leaf blades of its exemplars growing under the egret nests were on average larger, which provided greater surface of the assimilative apparatus, than of those growing outside the colony. All differences between the in the studied tree stands seem to reflect soil enrichment in nutrients caused by the excretions from egrets. Such changes in phytocoenoses caused by effect of bird colonies have been studied so far only in cold and temperate climates. Our results confirm a similar effect of birds' breeding on a plant community in a tropical climate. © 2012 Blackwell Publishing Ltd.