Identification of Acoustic Index for Revealing The Characteristics of The Lowland Forest Ecosystem of Alas Purwo

Biodiversity assessment is essential in the field of conservation, where mostly, it is conducted using an acoustic index as an indicator. A biased result can be avoided using the most suitable acoustic index by first characterizing the environmental conditions of the particular ecosystem utilizing sonotype method. This research combines the use of sonotype and acoustic index to characterize the lowland forest ecosystem of Alas Purwo. Data of recorded sound show the frequency range content, which refers to the dominant fauna groups. The acoustic index suitable for this fauna group is selected, and some variables were adjusted from the default conditions to meet the ecosystem conditions better. The results showed that the dominant fauna group was Aves with a sonotype of 50.82% and a frequency range of 252-4632 Hz. BIO and ACI were considered as the most appropriate indices. BIO with a frequency range modification enables us to describe the biophony activity, but it is also sensitive to geophony. ACI is also considered suitable for the lowland forest ecosystem because it can compare the occurrences of biophony to non-biotic sounds, where the intensity mostly fluctuates. Keywords: Biodiversity, Bioacoustics, Acoustic Index, Soundscape Ecology