Disassembly and functional diversity change in amphibian communities in degraded habitats in Indonesia (Sumatra)
Zusammenfassung der Projektergebnisse
In order to understand the determinants of biodiversity patterns, it is essential to identify the spatial and temporal distribution of animal communities and the driving processes involved in the assembly of communities. The challenge is to determine rules and processes that describe the disassembly of species in disturbed habitats, i.e., the sensitivity of species to disturbances as well as the reaction of entire communities. This project addressed the effects of anthropogenic habitat disturbance (selective logging, agricultural use) on species-rich amphibian communities in rain forest ecosystem in Indonesia (Sumatra). The project aimed at revealing the effects of anthropogenic habitat disturbance by an approach that integrates the analysis of diversity on the level of species, function, and communities. The study addressed patterns of diversity, processes that lead to these patterns, and predictions about diversity change. We successfully established a total of 48 line transects along a disturbance gradient (undisturbed rainforest, old secondary forest, i.e., 40 years after logging activities; young secondary forest, i.e., 10-20 years after logging activities; oil palm plantations). Along these transects, amphibian assemblages were regularly monitored (species composition, abundances, functional traits of species) and environmental data was collected (>10 biotic and abiotic variables). Even if timber logging is of relatively low intensity and considerably long ago, amphibian communities are still different from communities in pristine environments, but are equally diverse. Old secondary forest is a valuable habitat for amphibians and should receive equivalent attention in conservation as primary forest. Highly degraded habitat, such as oil palm plantations and secondary forests that were intensively logged and/or recently logged were very species depleted. Nevertheless, highly degraded secondary forest is still of higher conservation value than plantations; young secondary forest and severely degraded forest harbor proportionally more typical forest species compared to mainly ubiquistic species in oil palm plantations. Breeding ecology is an additional important factor in the sensitivity of amphibians to disturbance. Stream breeding species were found to be more sensitive to degradation than pond breeding species. Ponds within the forest usually represent naturally open habitat. This habitat is comparable in structure to anthropogenically open habitat as it is found in degraded forests. Therefore, pond-breeding frog species might be adapted to this naturally open habitat, and accordingly less sensitive to human degradation of forests. Although Indonesia is considered a mega-diversity country, the taxonomic knowledge on amphibians in Sumatra, and probably the total Sunda region, is obviously still poor. This study shows that the diversity of amphibians in Sumatra is severely underestimated. 20 % of all species discovered in this study are new candidate species, i.e. possibly new to science. Our study lets us predict that also in other parts of Sumatra, and generally in the Sunda region, amphibian diversity is much higher than so far identified. Accordingly, our work stresses the importance for quick and appropriate conservation actions to protect this high diversity on the background of rapid habitat loss.
Projektbezogene Publikationen (Auswahl)
- 2015. Amphibian diversity change in degraded habitats in Indonesia (Sumatra). Annual conference of GTÖ (Society of Tropical Ecology), Zürich, Switzerland
Jankowski A., Haas A., Iskandar D. & Glos J.
- 2016. Shift in amphibian species composition along a forest disturbance gradient in Sumatra, World Congress of Herpetology, Hangzhou, China
Jankowski A., Haas A., Iskandar D. & Glos J.
- 2017. Amphibian communities as indicators of forest disturbance in Sumatra, Indonesia. Xenodermus conference of Perhimpunan Herpetologi Indonesia & University Padjadjaran, Bandung, Indonesia
Jankowski A., Glos J, Iskandar D & Haas A.
- 2017. Simultaneous studies of ecology and taxonomy: Conservation efforts in data deficient habitats. SAGE (Southeast Asian Gateway Evolution) conference, Bogor, Indonesia
Jankowski A., Glos J., Haas A. & Iskandar D.
