- The Banggai archipelago is a remote landscape of around 97% limestone karst east of Indonesia’s Sulawesi Island.
- Extractive concessions on 39 locations on Peleng island, the largest island in the Banggai Islands district, may soon cut into the karst bedrock to mine the ancient limestone for cement, glass and other industrial applications.
- Indigenous villagers on Peleng Island say they worry the development could catalyze unprecedented local environmental damage, impairing the cultivation of unique yam varieties grown only here.
BANGGAI ISLANDS, Indonesia — Dewdrops cling to weeds in the Banggai archipelago as Deslin Kalaeng grasps a large round root vegetable from the ancient karst.
“That’s the Banggai yam,” she says, shortly after daybreak over the Maluku Sea. “It’s our source of life, other than rice.”
Deslin is known as the Ibu Kampung — “village mother” — of the Tolobuono Komba-komba Indigenous community here in the center of Peleng, one of a cluster of karst islands just east of the much larger Indonesian island of Sulawesi.
That honorific reflects Deslin’s advocacy against plans to quarry the limestone that surrounds Komba-komba village, and that makes up around 97% of the rest of the island chain, known as the Banggai Islands.
Karst systems like the Banggai Islands are landscapes of soluble bedrock riddled with caves and underground rivers formed by erosion from acidic water over millions of years. Around 15% of the world’s land surface is karst, or carbonate rocks, the most common of which are dolostone and limestone.
Indonesia accounts for around 155,000 square kilometers (60,000 square miles) of karst landscapes. Almost a tenth of this area has experienced degrees of environmental damage, mainly due to mining, according to Gadjah Mada University karst expert Eko Haryono.
The limestone karst in the Banggai Islands is an intact Swiss cheese of caves and springs that sustain this archipelago of around 130,000 people with water to drink — and to irrigate the nutrient-dense yams harvested by women like Deslin.
People here speak of no fewer than 20 local nutrient-dense varieties of the yam, which have grown here for longer than anyone can remember.
“What would happen if this limestone were to become extinct?” Deslin says. “The yams wouldn’t grow, and the water would vanish.”
The die is karst?
The prospect of change on this far-flung archipelago off Sulawesi feels increasingly close to Deslin.
Thirty-nine individual sites around Peleng Island may soon be dissected by limestone miners, according to data from Indonesia’s energy and mining ministry.
For now, just one of these 39 locations has a business permit that authorizes quarrying, known in Indonesia as an IUP permit. The remaining 38 are governed by a WIUP, an exploration license.
Limestone prospectors are consequently engaged in a charm offensive on the ground to woo residents in support of converting exploration into quarrying rights.
However, anecdotal testimony indicates that local opposition to the prospective quarries remains steadfast, in part because of the risks to Banggai’s simple food staple.
Together the exploration permits encompass 25 villages spread over an area of 4,036 hectares (almost 10,000 acres). That’s equivalent to less than 2% of the land area of Peleng Island, which is nearly as big as the U.S. state of Rhode Island.
However, civil society researchers worry that while the potential concession area may be a small proportion of Peleng, the eventual ecological damage and contamination to the aquifer could prove far-reaching.
Wandi, a campaigner at the Central Sulawesi office of the Indonesian Forum for the Environment (Walhi), the country’s largest environmental NGO, says limestone quarrying could irrevocably alter the local ecology.
“The target of mining exploitation is karst rock, which plays a role in providing clean water sources and supporting soil fertility for vegetation growth, such as Banggai’s yams,” Wandi says.
Infrastructure, sediment runoff and other side effects of limestone quarrying could open a Pandora’s box of environmental harms, with little hope left for Banggai’s yams in villages like Komba-komba, not to mention the rare wildlife that inhabits Peleng’s little-studied rainforests.
Soil loss and vegetation degradation from mining karst can catalyze rocky desertification, a process that “seriously restricts economic and social development and threatens human living space,” according to a paper published in May in the journal npj Heritage Science.
“Banggai’s yams can be planted again and again for centuries if they’re looked after,” says Yusman, director of the Indonesian Evergreen Association, a civil society organization based in Central Sulawesi province.
“Mining only needs 10 or 20 years to erase it all.”
Yams to the slaughter
Almost every home on Peleng Island has a plot of yams, says Imran, the head of the village council, or BPD, in Balayo village.
The harvest is the fulcrum of the family economy, bringing in up to 10 million rupiah ($610) per season. The fragile soil over the karst pays for basic needs, education and maintenance of the family home.
“I bought my motorbike with the money I earned selling yams,” Imran says.
Sago and root vegetables like the Banggai yam were staples across Indonesia before the military-backed Suharto government began subsidizing white rice via a network of crony suppliers in the 1970s.
Public health experts say reliance on refined white rice in Indonesia’s diet today has fueled millions of undiagnosed cases of diabetes, and supported a high burden of chronic conditions in the world’s fourth most-populous country.
Research published in 2019 from a district on Indonesia’s main western island of Sumatra found “a significant correlation between sago consumption with cholesterol and WC [waist circumference],” in comparison with refined white rice.
Twenty or so yam varieties in the Banggai Islands include the pulsus, which is pulverized to a goo then slurped by the island chain’s newborns.
Data from the Banggai Islands district government showed that Central Peleng subdistrict, which encompasses Komba-komba village, recorded a 16.5% rate of child stunting this year, below the national average.
The Indonesian health ministry’s 2024 nutrition census showed the nationwide average rate of stunting, which is impaired development due to chronic maternal and child undernutrition during early years, fell slightly to 19.8% compared with a year earlier.
Chalked off
Every first harvest season, the community holds a thanksgiving ceremony, in which people come together to pray and receive blessings, together with their yam.
The wild origin tale of the Banggai yam is recounted here, in which the youngest of seven siblings volunteers to become a yam, thereby saving his family a slow death from starvation. This yam can grow only on Peleng Island, the story goes.
“This story isn’t some empty fairy tale,” Imran says. “This is our way of preserving our heritage and remembering our origins.”
The cadence of preparing land for planting to harvesting the island’s yam binds the community, Indigenous elders say. Women gather up grasses. Men make support poles for plants. Children prepare the seeds.
Land-use change across 4,000 hectares threatens not only local livelihoods and nutrition, but the social fabric that binds this community.
“It isn’t just work,” Imran says. “It’s a ritual.”
Kast aspersions
Deslin and the farmers of the Banggai Islands are not alone in working to protect the karst. On the other side of Sulawesi Island, the Banggai farmers may look to Iwan Dento, who successfully led a five-year campaign to stop quarrying in Maros, South Sulawesi province.
In 2022, the head of Banggai Islands district, Rais Adam, enacted a decree establishing new restrictions on development on the karst, including a requirement that any development must be sustainable and not contribute to the extinction of local plants or animals.
That followed regional rules limiting development affecting the karst and springs, which were published in 2019 and 2014, respectively. Since then, however, “approximately 28 companies” have requested to changes to the district’s zoning plans, according to Walhi.
For Wandi at Walhi’s Central Sulawesi office, the regional government should be clawing back permits and preventing further applications, including the exploration licenses.
“Otherwise, the local government risks becoming the main actor creating a ‘time bomb’ for life on Peleng Island in the future,” Wandi said.
AMAN, Indonesia’s biggest civil group representing Indigenous peoples around the country, told Mongabay in 2023 that around five Indigenous communities lived within the prospective limestone concessions.
Only one company, PT Bangkep Mineral Selaras, holds a permit in Deslin’s village of Komba-komba. The company received a license to explore 86 hectares (212.5 acres) for limestone. Like more than a dozen other companies waiting to cut into this ancient island chain, it hasn’t received a permit to establish a quarry.
“If the mines come, we won’t just lose our land,” Imran says. “We’ll also lose our way of life.”
Deslin wears a rattan basket as backpack and a weary smile, recalling how earlier generations also farmed this landscape with little more than prayer and a machete.
The early-morning dewdrops are absorbed back into the soil, and Deslin contemplates what the change to the karst might mean for her society as she mops the sweat from her brow with a shirtsleeve the color of lavender.
“What would be left for our children and grandchildren?” Deslin asks.
Banner image: Deslin Kalaeng with some yam. Image by Christopel Paino/Mongabay Indonesia.
This story was first published here in Indonesian on May 13, 2025.
Citations:
Sun, M., Hong, S., Meng, J., Xiong, Q., & Xiao, S. (2025). Assessment and outlook of the global karst World Natural Heritage Sites based on threat intensity. NPJ Heritage Science, 13(1). doi:10.1038/s40494-025-01768-x
Syartiwidya, S., Martianto, D., Tanziha, I., Sulaeman, A., & Rimbawan, R. (2019). Association between sago consumption and NCDs’ clinical signs among those consuming sago in Kepulauan Meranti Regency, Riau Province, Indonesia. Journal of Food and Nutrition Research, 7(6), 476-484. doi:10.12691/jfnr-7-6-10
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