By Mukhlisi, Kukar Mining Team

The PAM method has been widely used as a tool for biodiversity monitoring in various parts of the world. However, its use in tropical forest areas of Borneo is still limited. Its application as an ecological indicator to understand the post-coal mining land recovery process has never been done, especially in Borneo. This is interesting because our study site is in the delineation area of Indonesia’s new capital city, which is planned to be designed as a forest city. We hope to study the process of secondary succession on anthropogenically damaged land from a soundscape perspective.

Our study site was in the concession area of a coal mining company in East Kalimantan Province. However, they have finished their operations several years ago. They have fulfilled their revegetation obligations and will return the concession land to the government this year.

In this BEAT Year 2 program we were mentored by Ben Gottesman, Wendy Erb, and Yen Yi Loo. They were very enthusiastic and happy to help our team. The 12-hour time difference between Indonesia and the US does not seem to be a barrier to conduct meetings and discussions via zoom. Thank you all…

Our team has installed 4 swift ones in post-coal mine reclamation areas under various land covers. 3 devices were installed in revegetation areas at different planting ages (2011; 2014; 2018) and 1 device was installed in a nearby intact forest as a comparison/control. Each swift one was set at 48 Khz sample rate, 28 dB Gain with continuous recording type. The first trial produced 36 days of recordings (Note: Deployment dates March 9 – April 15, 2024). This was beyond expectations, because when we checked the batteries they were still functioning well for more than 30 days. On April 15 the recorder was also rotated to a different revegetation area.

First deployment picture (March 9, 2024)

Some pictures of the study site in the post-coal mine revegetation area (March 9, 2024)

We started to find some challenges and obstacles after the trials in the first rotation. From some of these situations we also began to learn to find solutions.

• Two windscreens were damaged by the animals. In fact, the animal’s bite reached the micropohone. These are some of the pictures we took in the field.

The solution to this is to make a protector in the microphone section and buy some windscreen spare parts in the market place. However, the microphone does not seem to be sold freely. This is an example of a design made by one of my BEAT Year 2 colleagues (Rizki KurniaTohir) and suggested to me through a private chat.

• The next obstacle was that one of the recording units did not produce any recordings (0 files). This seems to be the result of us forgetting to press the turn on button. It is always a good experience to check before leaving the location. This is to ensure that the swift one is working properly.
• We also faced the challenge of selecting sampling locations. In most cases, it is recommended that soundscape studies be at least 500 meters away from the edge of the sampling site. However, selecting an ideal sampling location like this is not easy to do in coal mining areas.

Based on experience, coal mining companies rarely have large planting blocks. Revegetation blocks are usually small and unevenly distributed to suit the potential area with coal reserves. In this revegetation area, it is like choosing a complicated puzzle.

• Furthermore, our study also found that plant age did not seem to correlate with the quality of vegetation cover. This is understandable because the survival rate of each plant block varies, depending on the limited nutrients and top soil. Ex-mining land is generally very degraded and difficult to replant. Some of our solutions include trying to reclassify the quality of vegetation cover based on NDVI values. We just finished the NDVI analysis a few days ago.

Map of sampling locations based on planting blocks.

Map image of the location after NDVI analysis

I think we need to discuss the location again with the team and mentors. If the area of the sampling location is not ideal, maybe we will shift the focus of the soundscape to different animals, such as insects.

Additional Note:

I have also written an opinion column about PAM and Bioacoustics in a newspaper “Kompas”. This is one of the most popular newspapers in Indonesia. This was actually published late last year (December 19th, 2023). It can be read at the following link:

https://www.kompas.com/sains/read/2023/12/19/200000623/acoustic-monitoring-mendengarkan- voice-of-nature-to-understand-how?page=all