Koyra Upazila, Bangladesh – The Shakbaria river’s low tide has pulled the water back, exposing a wide, slippery mudbank between Suranjan Raptan and the edge of the Sundarbans, the world’s largest tidal mangrove forest.

For most of his life, Suranjan has relied on this forest as his pharmacy. He rises before the sun, crosses into the mangroves in a small boat and walks barefoot through the clay-mud jungle for hours, carrying a knife to cut the leaves, roots and bark he uses to make medicines.

Today, the 40-year-old traditional healer, or kabiraj, has come to borrow his uncle’s boat.

“Uncle, are you home?” he calls from outside the house.

Chapal Raptan, Suranjan’s uncle and a honey collector, is a medium-built man with sharp features.

“Suranjan? Come in and sit,” Chapal Raptan answers, his voice hoarse. “I worked in the rain yesterday; now I have a cold, so I’m resting.”

“Sad news,” Suranjan replies. “Drink hot tea with tulsi leaves and honey. It will help. I won’t sit now; I’m heading to the forest to bring back some plants. I want to take your boat.”

His uncle tells him where to find it.

“Okay, uncle. Rest well. If you feel worse, I’ll send medicine,” Suranjan says as he sets off.

Beyond the courtyard lies the road, then the Shakbaria river, and across it, the Sundarbans.

Suranjan finds the overturned boat and lowers it into the water. Leaves and fruits from the forest have gathered on the muddy bank. His feet sink deep into the sticky mud. He climbs into the boat, dangling his legs over the side to wash them, and the wind pushes him across small waves towards the forest.

Stepping into the Sundarbans, the smell of wet mud and salt fills the air. Mangrove roots twist up from the water like claws. Kingfishers sound sharp notes in the half-light; insects hum and leaves sway in the breeze. Suranjan walks barefoot, saying it allows him to feel the ground and move quietly, and that sandals slip too easily.

“A deer passed here not long ago,” he says, pointing to a small hole in the mud.

“These leaves,” he says at a bush, “boil them when the stomach aches.”

A few steps later, he touches the bark of a tall tree. “Scrape it, mix with water, it helps when the cough won’t go away.”

Then he finds a tall Sundari tree, with dark-green, oval leaves.

“This is the tree that gave the forest its name: Sundarbans. Now it is rare. We are lucky to see it here.”

He remembers a different forest.

“Before Cyclone Aila [in 2009], the forest was so dense that sunlight could not enter. Since then, it has thinned. The forest feels empty.”

The change became particularly noticeable around 2015 or 2016, he says, when sunlight began reaching places that had once been heavily shaded and familiar medicinal plants became harder to find.

Today he is looking for a particular tree. He searched for it the last time he came but could not find it. He worries it has disappeared.

Suranjan has been a kabiraj for 21 years. He learned from his father, who learned from his grandfather. Nothing was written down. He was taught how to identify plants, where to find them, which parts to harvest and how to prepare them - knowledge passed through practice and memory.

Suranjan lives in Koyra, in Khulna district on Bangladesh’s southwestern coast. From his yard, he can see the green canopy of the Sundarbans rising beyond the canal.

Twenty years ago, Suranjan says, scores of patients filled his yard, men and women, children accompanied by mothers or grandparents, people with coughs, fevers, wounds or stomach pain. Some carried bundles of leaves and roots for him to identify. The crowds began to thin about a decade ago. Now he treats a handful within the community.

Part of the change was happening in the forest. Regular cyclones and rising salinity were making some of the medicinal plants he depended on harder to find. But the choices available to villagers were changing, too.

Bangladesh had begun revitalising its community clinic programme in 2009, expanding primary healthcare in rural and hard-to-reach areas. By 2015, about 14,000 community clinics were operating across the country, offering basic health services closer to people's homes. Alongside them was a vast network of retail drug shops, where medicines were widely available, often without a prescription.

Suranjan watched as younger villagers increasingly turned to clinics, doctors and pharmacies, he says, while many of those who continued to seek help from kabiraj are older or have few affordable alternatives.

Today, Suranjan’s face carries the glow of a new father. Two days ago, his first child, a daughter, was born at her maternal grandparents’ home. Mother and baby are healthy, and the news has spread through the village.

Neighbours stop him as he passes.

“How are the mother and the baby?”

To younger neighbours, he smiles, places a hand over his heart and says, “With your blessings, mother and daughter are healthy.” With elders, he brings his palms together in greeting. Each encounter ends with another blessing for his newborn daughter.

At home, Suranjan lowers himself onto the smooth earthen floor. When someone suggests he sit on a rug, he smiles and refuses.

“One day I will return to this soil,” he says. “It feels special.”

When the conversation turns to payment, he shakes his head.

“I never charged money. People gave me whatever they could, and that was enough. I was never doing it for money.”

A small electric fan stirs the heavy air. Suranjan disappears into the next room and returns with another. Even after a night and morning of relentless rain, the heat clings to the air.

“It wasn’t always like this,” he says. “A few years ago, after rain, the air would turn cool. I’d put on a long-sleeved shirt, sometimes even a thin scarf at night.”

The Sundarbans stretches across 10,000 square kilometres of Bangladesh and India. Its green canopy shelters the Royal Bengal tiger, saltwater crocodiles and more than 300 plant species. Nearly 2.7 million people live in the coastal districts surrounding the forest on the Bangladesh side alone.

For generations, communities here have turned to the forest for food, firewood and medicine. Kabiraj have long provided care in rural areas where formal medical services can be difficult or expensive to access.

Their remedies are made from leaves, roots and bark, and their knowledge has traditionally been passed from one generation to the next. A 2011 study of medicinal plants in Barisal Division found that almost one-third of rural households in the coastal area sought help from kabiraj or similar healers.

Rising seas and repeated cyclones are pushing saltwater further into coastal ecosystems. Between 2017 and 2021, salinity in tidal water rose from 21 to 33 parts per thousand in the pre-monsoon season, while soil salinity increased by 31 percent.

Mangroves are adapted to salt, but tolerance varies by species. The Sundari (Heritiera fomes) is declining. Bain (Avicennia officinalis), an important source of nectar for bees, has stopped flowering in some places. Medicinal plants that kabiraj depend on are also becoming harder to find.

For Suranjan, the evidence is in what is no longer there.

As the tide enters the forest, fiddler crabs move across the mud. He stops beside a tree and carefully cuts a section of bark with his knife.

“Between the wood and the bark there is a layer. If that layer is not hurt, the bark grows back quickly. If it is damaged, the bark takes longer to grow, and sometimes it never grows again, the wound stays.”

When harvesting a vine, he never pulls out the whole plant. He cuts only what he needs so it can grow again.

But careful harvesting cannot protect plants from changes in the water itself.

“Before, during the tide, the forest did not sink completely. The higher ground stayed dry,” he says. “But now the forest goes fully underwater, and because of the saltwater many trees are dying.”

He names species that have become difficult to find: hogla, or Typha, whose fibres are traditionally applied to cuts and burns and whose roots are used in local remedies; and bain, whose bark and leaves are used in traditional medicine and whose flowers provide nectar for bees.

“My father collected more than 100 medicinal plants from different parts of the country and planted them in our garden,” he says. “But because of Cyclone Aila in 2009, saltwater entered and destroyed all our plants; they all died.”

Professor Md Abdur Rahim, chairman of the Department of Genetics and Plant Breeding at Sher-e-Bangla Agricultural University, describes a forest whose botanical balance is shifting.

“Salt is slowly rewriting the forest. The hardy trees may survive, but the plants that heal, the ones kabiraj rely on, are disappearing,” he says. “As salinity rises, the forest changes its face: salt-loving species spread, while the delicate, medicinal ones fade.”

A season without flowers

Nearby, a small tea stall filled with wooden benches stands beside the Shakbaria river. Inside, a television sits silent during the day; villagers gather around it in the evening. The morning rain has left water pooled on the road and clouds hanging low over the river.

Customers drink strong black tea with sugar, sometimes with biscuits.

Suranjan’s uncle, Chapal Raptan, the honey collector, sits on one of the benches.

Asked how much honey he gathered this season, Chapal, having overcome his cold, shakes his head.

“This is the time for bain flowers,” he says. “But this year, not a single bain tree has bloomed. There is no bain honey at all.”

Several men respond at once.

“We have never seen this in our lifetime,” one says as the others agree. “Not a single flower on the bain tree.”

For men who have spent their lives entering the forest, the missing blossom is more than a poor honey harvest. It is an unfamiliar change in a landscape they thought they knew.

Suranjan names other medicinal plants he says are becoming difficult to find around Koyra: neem, ashwagandha and haritaki.

Then he looks down at his hands.

“It is becoming difficult to collect medicinal plants. Since I don’t have all the necessary medicines in my collection, I cannot give patients what they need on time when they come.”

Three houses away from Suranjan lives Deepa Mandol, 32. On the veranda, she sits beside her husband as he takes medicine. Their six-year-old son has just bathed and is waiting to eat.

“Suranjan-da [brother] is the first person I go to when someone is sick in my family - fever, cold, cold-cough or feminine physical problem. If you go to him, he will make medicine,” she says.

Her husband has hepatitis B. Some people use local herbs to ease symptoms such as jaundice or to feel better, but these cannot remove the virus from the body.

The family sits on a wooden khat in the yard. Deepa, barefoot in a pink sari, begins feeding her son rice, fish and potatoes with her hand.

“I do not have money for the doctor in town. The clinic is far. The medicines are expensive. Suranjan-da never charges.”

Clinics and private doctors’ chambers operate in Koyra, but reaching them from settlements near the forest can mean travelling by boat or rickshaw. A private consultation typically costs about 500 to 800 taka ($4-$7), before medicines and transport. Government facilities are cheaper, but residents say waits can be long and medicines are not always available.

A little farther along the road, 80-year-old Suvodra Mondal watches over her goats in the late afternoon. The wind from the Shakbaria river lifts strands of her white hair.

She suffers from joint pain and stomach problems.

“I often have headaches and pain in my knees from arthritis,” she says. “I collect medicine from my nephew, Suranjan Kabiraj. He prepares it with plants, mixes it with honey, and gives it to me. After taking it, I feel some relief.”

She has also sought medical treatment in town.

“I went to see a doctor in the town, but they said treatment would cost a lot of money. My son catches fish in the forest to eat, how could he ever afford tha