Lambir ants project

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Dyna Rochmyaningsih, Anasuya Chakrabarty and Sopark Jantarit

Contents

Abstract

Ants are one of the most prominent arthropods, which are dominant over a wide range of habitats. They form an integral part of the rain forests of Borneo. The primary dipterocarp forests and the secondary forests harbor different species of ants and the two habitats are expected to vary in diversity. We expect that the secondary forest is more diverse than the primary forest, due to its more disturbed structure. As it is more disturbed, it harbors invasive species as well as native ant species, and have more light and space compared to the primary forest.To examine this hyphothesis, pitfall traps were set in primary and secondary forest with three replication in each type of the forest. Result showed that there is no significant different in the species diversity between primary and secondary forest (p value=0.1).However,Technomyrmex sp and Pheidole sp were found as the generalist species in the two different habitats. In addition, a huge number of Anoplolepis sp and Leptogenys sp--they were all invasive species-- were found in the secondary forest.

Introduction

The tropical rain forests of Borneo has been one of the most incredibly diverse forests of the world, with its unique characteristics and a huge range of endemic species (Wallace,1869). There are about 1175 species of trees in Lambir Hills National Park and about 2200 in Borneo. The immense diversity of plants also corresponds to the diversity of animals, especially the arthropods. The ants constitute a major part of the arthropod diversity. The Bornean rain forests consist mainly of the hill forests of mixed dipterocarps, the lowland alluvial forests and the peat swamps and karangas. The hill forests can be differentiated into primary dipterocarp forests and the secondary forests. The secondary forests are those which grow after deforestation and hence have more regenerating trees.(Yanoviak, 2007). The secondary forests also get more light and space which may affect the biodiversity of certain organisms. Due to the more disturbed condition of secondary forests, they may also harbor more invasive species of ants in addition to native species.( Yanoviak,2007). So the ant diversity may vary between the primary and secondary forests and the secondary forest might turn out to be more diverse. We also intend to see some indicator species for both the forest patches, which may give us an idea of the forest type and the ecological variation between them.

Question

Our question is whether the ant diversity is more in secondary forest compared to the primary forest. And we hypothesize that the secondary rain forests are more diverse than the primary rain forests.

Methods

Field methods

Study area

This study was conducted at Lambir Hill National park, Borneo, Malaysia during 10-12 June 2010.

Habitat characteristics

In this study, two habitat types were selected for this investigation. There were primary forest and secondary forest. We determine the site as primary forest due to its undisturbed condition and its continuous canopy. Three areas then were selected at random with covering both habitats. Each habitat had three replications and stayed apart for approximately 500 meter.

Ant sampling

Ants were sampling using pitfall traps from the two different habitats. The traps (6.5 cm diameter and 8.5 depth), partially filled with detergent, were placed and remained in operation for 30 hours.

Identification

All samples were stored in bottles. Processed specimens were separated into similar taxa (i.e family, subfamily, genus, or morphologically similar groups). The specimen were identified to the genus level using the key of “Identification Guide to Bornean Ants” based on the external morphological characteristics of worker stage.

Analysis

Shannon-Wiener diversity index was used to take into account ant species diversity within each sampling areas. Wilcoxon test was calculated to compare the habitat sites for significant differences in the diversity indices of the three sampling areas and cluster analysis was performed. All calculations were made using “R” program. Anosim was used to calculate the similarity indices between the three data sets.

Results

Species composition Totally, In this project, we found 4 subfamilies 7 genera and 12 identified species while 11 unknown species were remain a mystery from primary and secondary forest. The identified species were Camponatus gigas, Paratrechina sp1, Anopholepis gracilipes, Anopholepes sp,Technomyrmex sp1, Technomyrmex sp2, Pheidole longipes,Pheidole sp1, Pheidolegiton sp1, Pheidolegiton sp2, Leptogenis sp1, and Leptogenis sp2.

2. Primary forest vs Secondary forest Based on the wilcox.test that has been done, the Shannon Wienner diversity index of the primary forest and secondary forest is not significantly different.

Table 1: Similarity Box plot by the Bray- Curtis method
Figure 1: The cluster dendogram of the ants species composition between primary forest (PF) and secondary forest (SF)

The cluster dendrogram shows that the PF1 and PF2 are closely similar. The same phenomena can also be seen in SF1 and SF2. But we can see here that SF3 has the most dissimilar position compared with the other plots.

Discussion

As depicted in the result, there were no significant difference between primary and secondary forest. The p-value for this analysis was 0.1 which means that there were no significant differences between the two habitats. However, in the secondary forest plot 3 (SF3), we found some invasive species like Anoplolepis sp and Leptogenys sp in a huge number (135 individuals for Anoplolepis sp and 159 individuals Leptogenys sp). If our sample size was bigger then we could have expected our predicted result. We can also find similarity between primary forest and secondary forest in the dendogram (PF1 and PF2, SF1 and SF2). However, SF3 and PF3 were unique. We suspect that it maybe because the character of the site that is near the disturbed area (the site was located in Lambir Hills Main Trail). In addition, the ANOSIM analysis showed that there was no significant difference between primary and secondary forest. It means that the two areas are similar. For instance, in the context of species composition, we found Technomyrmex sp and Pheidole sp as the overlapping species in both areas.

References

  • Stephen P. Yanoviak, Nalini M. Nadkarni1,4, and Rodrigo Solano J. (2006), "Arthropod Assemblages in Epiphyte Mats of Costa Rican Cloud Forests"
  • Identification Guide to Bornean Ants, Y. Hashimoto.