A comparison of ground-dwelling and arboreal ant assemblages (Hymenoptera: Formicidae) in lowland forests of Cambodia

This paper presents the first comprehensive description of the ant fauna of Cambodia, most of which has not yet been extensively surveyed. The aim was to investigate ground-dwelling and arboreal ant fauna in three types of lowland forest in Cambodia and assess the bioindicator value of ant communities along forest disturbance gradient. The ground ant fauna was sampled by Winkler extraction, and the arboreal ant fauna by time unit sampling. A total of 101 ant species belonging to 40 genera in nine subfamilies was collected. Of these species, 41 were collected in the community forest (CF; habitat with high disturbance), 52 in regrowth forest (RF), and 61 in natural (undisturbed) forest (NF). Although the total species richness hence declined with the level of disturbance, it did not differ significantly among the three forest types. A comparison between ground and arboreal fauna showed an overlap of nine species (22%) in CF, 4 spp. (8%) in RF, and 7 spp. (11%) in NF. Non-metric multi dimensional scaling revealed that the ground ant fauna in CF greatly differed from the ground ant fauna in both RF and NF, which were rather similar in their species composition. Conversely, the arboreal ant fauna in the CF differed less from the arboreal ant fauna in RF and NF sites. However, there was much a higher occurrence of invasive ant species in CF than in the other forest types. The results suggest that higher level of disturbance due to logging and inundation common in community forests affects more the ground than arboreal ant fauna. The high number of ant species collected, well-defined vertical stratification of their communities, and the relatively high species turnover along the forest disturbance gradient confirm the importance of Cambodian lowland forests for biodiversity conservation programs and of the ants as usable indicator animal group of the disturbance.