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Habitat loss through anthropogenic activity is the single largest conservation problem, and alongside this vast areas of remaining habitats have become fragmented. (Krebs 1994). Fragmentation is the replacement of indigenous areas by other ecosystem types; this process usually has a negative effect on the existing biota. One of the most documented examples of this is the fragmentation of native forests, and tropical rainforest fragmentation is one of the largest concerns to conservationists. Alongside fragmentation anthropogenic disturbances include individual tree harvesting and clearing of forests for farmland. There is evidence to suggest that heliothermic reptiles benefit from forest disturbance.

Vitt et al (1998) studied the differences in natural treefall and individual tree harvesting by humans, in relation to heliothermic and non-heliothermic teiid lizards. Comparisons were made between the thermal environment of natural and anthropogenic treefall sites, whether lizards were affected by the gaps left from treefalls and whether there were any indirect costs of the harvesting activity. They found that anthropogenic gaps had higher light and temperatures on the ground than natural treefalls and this was attributed to the lack of understorey left at these sites. There was also a reduction in the number of microhabitats at the human sites as there was less shade and reduced arboreal runways. The natural sites maintained a high species diversity.

Vitt et al concluded that the loss of microhabitats was the main problem for the non-heliothermic species which require shade which is lost through tree harvesting. They also found that the anthropogenic treefall sites were unsuitable for the majority of forest species. However the heliothermic lizards appeared to benefit from the harvested sites as they provide areas for the species to bask. Indirect effects were also proposed, for example they suggest that the creation of basking site would allow the heliotherms to be advantaged in foraging opportunities which may place additional pressure on the resource base. Also although there is no evidence of this it can be assumed that should harvesting activity be such that the lizards can travel easily between treefall sites they will have access to vast areas of forest resources which they would not normally be able to travel to. Invasion of heliothermic lizards into areas of rainforest previously unavailable to them will have a negative impact on the surrounding environment. (Vitt et al 1998).

This is not the only study to provide results and proposals of this nature. Sartorius et al (1998) studied a specific teiid lizard species Ameiva ameiva in particular the basking/foraging behaviour of this species in different habitat types and at different temperatures. The most obvious differences in habitat was between the open grasslands and the rainforest. The findings of their study led them to speculate that some species will benefit from these changes whereas others will suffer suggesting that Amevia is one of the species that would benefit due to its wide distribution, open habitat association, colonizing ability and ecological plasticticity. (Sartorius et al 1998). As Vitt suggested Sartorius et al also propose that opening up the canopy would allow Amevia access to basking sites otherwise inaccessible to it and thus allowing it access to previously unavailable resources.

The removal of rainforest canopy allows the species to extend to foraging areas to which it would otherwise be restricted. It should also be noted that the natural treefalls will only cause a temporary basking site as the lower canopy will regenerate very quickly whereas anthropogenic gaps will not regenerate as fast. It was found that Amevia used harvested treefall gaps significantly more frequently that natural sites and at one site the edges of the forest were also used more frequently.

It is clear that forest disturbances assist heliothermic reptiles in providing suitable basking sites which can then have the knock on effect of allowing them greater foraging potential this can place an additional strain on the remainder of the herpetofauna community namely amphibians which are a prey species that may be experiencing difficulties finding suitably moist habitats in areas of logged forest

Methodology

Work on the herpetofauna of Buton island, South East Sulawesi took place in the dry season of 2002. A pit line trapping method was used in two of the forest reserves, Kakanauwe and Lambusanga. 25 pit traps were used at each site within and around the forest grids. Each trap site had 5 buckets and one funnel trap. The pit traps were checked every morning. The traps were placed at least 100m apart and the traps sites were selected according to differing levels of disturbance. Generally the Lambusango reserve is less disturbed than Kakanauwe however comparisons were made between individual sites and not between reserves.

Habitat structure surveys were also undertaken at each site. Two 5×5m quadrats were used on either side of the pit line. Within these quadrats the following measurements were taken:

The following measurements were also taken within a 20m radius of the centre bucket at each pit line:

The aspect and gradient measurements were also recorded and canopy photographs were taken at either end of each pit line.

At this stage no statistical analysis has taken place however the initial results show that some species are more abundant than others. 1485 reptile individuals were trapped, the five most common reptile species are shown in table 1.

Species	Number recorded
Sphenomorphus varigatus	456
Mabuya rudis	332
Calamaria apraeocularis	284
Lygosoma bowringi	112
Cyrtodactylus jellesmae	99
Total	1283

The sites with the greatest number of reptile captures are shown in table 2. These sites are all situated in the Kakanauwe reserve.

Site number	Number of captures
49	67
41	55
1	50
12	49
44	46
47	44
42	42

Statistical analysis will be undertaken to analyse the correlation between forest disturbance and reptile abundance.

A dissertation entitled The impacts of forest disturbance on herpetofauna communities will be produced by Helen Pheasey, University of Brighton by April 2003.

Krebs C.J. (1994). Ecology Fourth Edition. Addison-Wesley Educational Publishers. Inc. USA.

Sartorius, S.S, Vitt L.J and Colli, G.R (1998). Use of Naturally and Anthropogenically Disturbed Habitats in Amazonian Rainforests by the Teiid Lizard Ameiva ameiva. Biological Conservation 90 91-101.

Vitt L.J. Avila – Pires, T.C.S, Caldwell, J.P. and Oliveira, V.R.L (1998). The Impact of Individual Tree Harvesting on Thermal Environments of Lizards in Amazonian Rain Forest. Conservation Biology, 12, 654 – 664.

Introduction

Methodology