Isolated trees as foci of diversity in active and fallow fields.
2000
Dunn, R. R.
As the percentage of forest converted to agroecosystems in the tropics rises, it becomes increasingly important to understand how biodiversity can be managed in these ecosystems. In this study, tests were made of the hypotheses that insect abundance and diversity are higher near isolated trees in crop fields than in the open and that the diversity and abundance of insects increases with the density of isolated trees. The field site was in the Nkoronza district of the Brong Ahafo Region of Ghana, in the dry semi-deciduous forest zone at 350 m altitude, and the study was done in the dry season of January-March 1998. Eight fallow fields (2-3 yr old fallows) and 8 active fields (planted with cassava and some yams) were investigated; the fields had a range of tree densities (6-48/ha). Ant species richness, ant abundance and beetle abundance per trap were higher near isolated trees than in the open. Isolated trees had less of an effect on beetle abundance in fallow than active fields. Ant species richness was positively correlated with tree size. Ant species richness per field, ant abundance and beetle abundance per field were not correlated with tree density or the condition of surrounding fields. These results indicate that isolated trees can play a role in determining the local distribution of ants and beetles in crop fields.
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Эту запись предоставил Forestry Research Institute of Ghana