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S4G Indonesia Diaries - Part 3

Sulawesi and the Restoration Station

After our earlier adventures, releasing orangutans and fighting illegal logging, it came to the last leg of Space4Good's journey. After some flight reschedules, delays, and a quick airport nap, Lisa, Thijs and Max went to Temboan. Here, we would be gathering field data to improve biomass models for young planting sites. In the meantime, Mathieu eagerly worked through all notes in a Balikpapan hotel before flying back home to the Netherlands. 

We soon arrived in Tomohon, a place the Space4Good team visited back in 2022 - close to the Temboan afforestation area. The first day in Tomohon was all about planning and preparation. Catching up on some much-needed sleep. At a large dinner table, with a view of Mount Lokon, we started planning the drone flights and the fieldwork. Of course, the view enticed, so the team took to action and climbed the active volcano to gain some much-needed perspective on the work ahead. A little drone flight was deemed necessary for - reasons - and the hike by the uneven and slippery ground of the lava flow of the last eruption was easier for some than for others…

Figure 1. The view of active volcano Mount Lokon while planning.

Onwards to Temboan!

Nestled in Sulawesi, Temboan is a little tropical paradise. Fresh coconuts everywhere, a beach with coral reefs and turtles, caves, trees, and watch towers for the views and project oversight. And of course, work to be done! In a two-hour drive from Tomohon, through volcanic craters, and past mixed plantations, we arrived at the Temboan camp greeted by a refreshing coconut to rehydrate from the drive, we then made our way to the afforestation site. Here, a lot has happened in the last two years.

Figure 2. Temboan area viewed from one of the watchtowers.

So what has been going on here?

After a series of fires due to land degradation and mismanagement in the area, alang-alang grass started growing. This tall growing grass is very flammable and relies on fire to spread. So when the grasses take over, more fires occur, and when there are more fires, more grass starts growing. This vicious cycle can be hard to break for nature. This means that fires that started decades ago still scar the landscape affecting biodiversity and encouraging low-value grassland. Grass has to be cut regularly to prevent fires, and trees are planted. Only when the trees become dominant are the grasses suppressed by nature.

Because this phenomenon of invasive grass has become a problem in Indonesia and surrounding countries this innovative and challenging reforestation project aims to be an example project to catalyse similar reforestation efforts in the region. The goal is to plant a new tropical rainforest in just three years. The pioneering method is designed by Dr Willie Smits and his team at Masarang Foundation. The special method includes planting in multiple phases to combat the fast-growing grass, using biochar for the soil and benefits the local community by boosting employment. Space4Good is supporting this project by accurate monitoring of the reforestation. Our team members had the honour to visit this project twice and the visible change in the forest in just over a year was incredible. Overall, by restoring the area to its natural state, more species of plants and animals are coming back. Slowly but surely the area is recovering and flourishing into a coastal forest once more, and with it, it has brought rain.

Figure 3. Temboan reforestation area with a rain cloud seen in the back.

For the field data collection for the biomass models, a planting site with a young forest close to the watchtower was selected. From here, we conducted drone flight campaigns where we deployed drones along carefully selected flight paths with LiDAR and multispectral sensor payloads. Here we could make good use of the terrain, by standing on the high ground to maintain connection with the drone, supported by having our spotter on the watchtower.

Figure 4. Max spotting the surroundings from the tower while the drone is lifting off for the LiDAR data collection.

As heavy clouds rolled in from the south, we sped up the data collection. The last time we were here, some precipitation issues leaked through the sensor, causing major issues in the device. We couldn’t have that happening (again). As the clouds seemed pretty happy staying south of us, and the flights were taken care of. Now it was time to measure some trees!

Figure 5. In-situ measurements of the newly planted trees to collect ground truth biomass data.

As there was current maintenance - the cutting of grass - being done on-site, and this was our first time visiting the plot, we had to improvise to get the job done. Traditionally, we would make plots and measure all trees within them. Here, because the trees are planted evenly spaced, and we had high-resolution data, we made elongated plots and recorded the trees as individuals. Of each tree, the diameter at breast height (dbh) and the height were recorded. With these, using allometric equations, we can calculate the volume of the tree. If we add the wood density, we come to the biomass and carbon of the tree. This we use to model the rest of the trees and extrapolate the biomass values for the entire field.

As the day was nearing an end, and since the roads were not all of good quality, it was time to say goodbye to our tropical paradise. After a quick swim and another coconut of course!

Figure 6. After a long and hot day of fieldwork the team could rehydrate with coconuts.

As our expedition in Indonesia was drawing to an end, we finalised our work. Data needed to be checked and processed before we could leave, to take action if there were issues. Luckily, all were approved for analysis.

Just before we left, we luckily managed to catch up with Dr Willie Smits, to dive more into the use cases, and place our trip in the larger perspective. After a long and intense travel, time to head home, process, analyse and catch up on sleep. We successfully gathered the data we needed for the project. Time to head home and make some nice models to calculate the biomass of the field, and show a proof of principle on how to map out these young plantations!

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