The impact of hedgerows on diversity of ants (Hymenoptera: formicidae) in the farmlands adjacent to Kakamega forest, Kenya
Odanga, James Jeconia
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African rainforests are lost at a high rate every year and most of the cleared areas are transformed to agricultural land. Such anthropogenic influences potentially result in biodiversity changes of major conservation concern. In ecosystems near Kakamega Forest, the conservation of some fauna depends on their survival in adjacent agricultural lands. Therefore, understanding the biodiversity potential of field margin vegetation or hedgerows and the interior of agricultural fields was vital to guide in conservation approaches. The study analyzed the value of hedgerows for conserving the diversity of ants (Hymenoptera: Fonnicidae) in farmlands adjacent to Kakamega Forest. Ants were sampled on 19 study sites between March and May 2009. In each study site, two transects each of 50 meters were established: one transect directly on the hedgerow, the other one in the interior of the farmland. On each transect, 6 pitfall traps were placed at intervals of 10 meters. A total of 10, 657 ant specimens consisting of 58 species were sampled within the farmland habitats adjacent to the Kakamega Forest. This was well explained by evaluation of the habitats using species accumulation curves and several environmental parameters. The hedgerow habitats showed higher species richness of ants compared to the farmland habitats. Further analysis revealed that as one moves away from the forest margin at a distance interval, the species richness decreased gradually. Evaluation of temperature using paired t-test proved that hedgerows had a lower mean compared to farmland habitats with a p-value < 0.01. Hedgerows were extremely rich in floral species with a total 92 recorded and provided better habitat conditions for ants, including dead wood and shade, which strongly differed from the interior of the farmlands. The study concluded that hedgerows mimic natural ecosystems to a certain level and attracted some of the forest dependent ant species. The farmland habitats in tum attracted mostly ant species that are very common in secondary forest which is related to open area or farmland habitats. The study, therefore, recommended that conservation of agro ecosystems should be enhanced by planting of more hedgerows in croplands. Keywords : Ants, hedgerows, biodiversity, farmlands, temperature, Hymenoptera, Fonnicidae, Kakamega Forest.