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University of Cape Tow (1997)

Conservation value of road verges in semi-arid ecosystems : ants (Hymenoptra formicidae) as bio-indicators

TSHIGUVHO THIDINALEI ENNIE

Titre : Conservation value of road verges in semi-arid ecosystems : ants (Hymenoptra formicidae) as bio-indicators

Auteur : TSHIGUVHO THIDINALEI ENNIE

Université de soutenance : University of Cape Tow

Grade : Master of Science (Conservation Biology) 1997

Résumé
Ground-foraging ants (Hymenoptera : Formicidae) are used to assess the conservation value of road verges in a semi-arid region around Prince Albert, Western Cape Province, South Africa. Ant communities were sampled using pitfall traps at 50 sites along two roads. Four transectswere sampledat each site, two in the road verge and two in the adjacent rangeland. A total of43298 individuals from 34 species were caught. There were 31 and 32 species observed in the road verges and the adjacent rangeland respectively. On average, road verges were more species-rich than the adjacent rangelands. Road vergesalso contained rare species, namely, those species that occurred in less than 10% oftraps. Ten species preferred road verges to the adjacent rangeland. No alien ant species were observed in the study area. The pattern ofspecies richness was similar at bothfencedand unfencedsites. Ant species richness appears to be influenced by food availability in the area. Ant species in the rangelands seem to be negatively impacted by higher grazing intensities. Species in the road verges on the other hand may benefit directly from road kills ; and indirectly from low grazing intensity, surface run-off, and possibly increased soil surface temperatures.No significant correlation was observed between road verge width and species richness in the road verges.Resultsjrom this study suggest that ant species use road verges more frequently as feeding sites, rejugia, or nest sites than adjacent rangeland. Road verges play a valuable role as conservation areas for ant fauna in this semi-arid region and should beprotectedfrom disturbance.

Mots clés :  : Ants, Formicidae, road verges, karoo, semi-arid, South Africa.

Annonce (NRF)

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