Impacts of Tropical Forest Disturbance Upon Avifauna on a Small Island with High Endemism: Implications for Conservation

Thomasedward Martin,Georgealan Blackburn

doi:10.4103/0972-4923.68914

Abstract

Tropical forests are rapidly being lost across Southeast Asia and this is predicted to have severe implications for many of the region's bird species. However, relationships between forest disturbance and avifaunal assemblages remain poorly understood, particularly on small island ecosystems such as those found in the biodiversity 'hotspot' of Wallacea. This study examines how avifaunal richness varies across a disturbance gradient in a forest reserve on Buton Island, southeast Sulawesi. Particular emphasis is placed upon examining responses in endemic and red-listed species with high conservation importance. Results indicate that overall avian richness increases between primary and 30-year-old regenerating secondary forest and then decreases through disturbed secondary forest, but is highest in cleared farmland. However, high species richness in farmland does not signify high species distinctiveness; bird community composition here differs signifi cantly from that found in forest sites, and is poor in supporting forest specialists and endemic species. Certain large-bodied endemics such as the Knobbed Hornbill (Rhyticeros cassidix) appear to be sensitive to moderate disturbance, with populations occurring at greatest density within primary forest. However, overall endemic species richness, as well as that of endemic frugivores and insectivores, is similar in primary and secondary forest types. Results indicate that well-established secondary forest in particular has an important role in supporting species with high conservational importance, possessing community composition similar to that found in primary forest and supporting an equally high richness of endemic species.

Highlights

Southeast Asia’s rainforests are facing the highest relative rates of habitat destruction of any major tropical area (Mayaux et al 2005, Achard et al 2002) and this has been identified as the major driving force of potential biodiversity loss across the region (Sodhi et al 2004a)
Similar patterns of decline have been found in other large-bodied Sulawesi endemics
This study has demonstrated that the response of avifaunal assemblages to anthropogenic disturbance in the Lambusango reserve is subject to considerable complexity

Summary

Introduction

Southeast Asia’s rainforests are facing the highest relative rates of habitat destruction of any major tropical area (Mayaux et al 2005, Achard et al 2002) and this has been identified as the major driving force of potential biodiversity loss across the region (Sodhi et al 2004a). This has severe implication for the biodiversity ‘hotspot’ of Wallacea, a biogeographical region where a complex geological history has facilitated a high prevalence of endemic fauna (Whitten et al 2002, Myers et al 2000, Kinnaird 1995). Predictive extinction models estimate that continued habitat alterations on this scale could result in the loss of up to 42% of flora and fauna species across Southeast Asia by 2100 (Sodhi et al 2004a), consequences could be more severe still in the Wallacea region due to its insular nature, being comprised of 13,500 oceanic islands

Methods

Results

Discussion

Conclusion