Abstract:
The aim of this study was to assess the structure of ground-dwelling ant fauna (class
Insecta; order Hymenoptera; family Formicidae) as well as the nest abundance and
species diversity in peatland that had been converted into oil palm plantation and
industrial pulpwood plantation (HTI). This study was carried out in Bukit Batu area,
Bengkalis District, Riau Province. Four oil palm plots (all about 5-6 year-old Elaeis
guineensis stands) and four HTI plots (all about 5-6 yr-old Acacia crassicarpa
stands) were selected as sampling sites. In each selected plot, four separated sampling
transects of 25 m x 2 m were established. Ground-dwelling ants occurring within the
plots were sampled directly from their nest holes. There were in total only 13 ants
species encountered, of which the most frequently-encountered ant species were
members of Formicinae and the least one was member of Ectatomminae. Eleven of
them (Anoplolepis gracilipes, Anochetus sp., Dolicoderus sp., Gnamptogenys sp.,
Iridomyrmex sp., Meranoplus sp., Odontoponera transversa, Odontomachus sp.,
Pheidole sp., Paratrechina longicornis, and Tapinoma sp.) were found in oil palm
plots and eight (Anoplolepis gracilipes, Iridomyrmex sp., Odontoponera transverse,
Odontomachus sp., Pheidole sp., Paratrechina longicornis, Camponotus sp., and
Polyrachis sp..) were encountered in HTI plots. Inter-plot similarity in species
assemblages between oil palm plantation and HTI was averagely 53,5% (Sørensen
Similarity Index). Similarity between oil palm plots was averagely 75,9% and
between HTI plots was 57,9%. Species diversity at plot level was invariable low in
both land use types (values of Shannon Weiner Index ranged only 0.22-0.24). Species
with highest encounter frequency and most abundant nests in oil palm plots were
Odontomachus sp. and Pheidole sp., while in HTI plots Iridomyrmex sp.,
Paratrechina longicornis and especially Anoplolepis gracilipes were the dominant
species. Average overall nest density was 1000 nests/ha and 1112.5 nests/ha in oil
palm plantation and HTI, respectively.
