Wednesday, Dec 07, 2022

Sundari Trees In Sundarban Delta Are Dying A Slow Death. Is Anyone Listening?

Sundari Trees In Sundarban Delta Are Dying A Slow Death. Is Anyone Listening?

Sundari trees, after which the mangrove forest is named, are on the brink of extinction in West Bengal due to excessive logging in the past for its high value wood and now with seawater rise.

An aerial view of mangrove jungle. Ananda Banerjee

The story of the Sundari is as fascinating as its namesake – the Sundarbans, the world’s largest contiguous mangrove forest, situated in the eastern state of West Bengal, India and Bangladesh. Sundari is as elusive as the most celebrated resident here—the Bengal tiger.

One might spend days on boats—the only way to tour the dense foliage of mangrove forest, which is also a designated national park, tiger reserve and biosphere reserve mostly during the months of October to May, before the heavy monsoon showers—yet spot none of the two iconic species here. Ironically, both species have been assessed as endangered by International Union for Conservation of Nature (IUCN) Red List of threatened species.

Yet, one species is totally under the global spotlight, millions spent on its protection and conservation while the other dies a silent death, unknown and unsung. If you are wondering which is which, the Bengal tiger is the former and the Sundari tree, unfortunately, is the one that struggles to hold its ground.

Sundari means “the beautiful” in Bengali. And very few would recall today that the mangrove forest, a UNESCO world heritage site, itself is named after the once abundant Sundari tree.

(Bonnie Camp, Sunderban Biosphere Reserve)

The Sundari is the dominant mangrove tree species of the Sundarbans of India and Bangladesh. Scientifically known as Heritiera fomes, it is a species of mangrove in the family Malvaceae. The Sundari tree can grow up to 60 feet in height with a girth of six feet. The tall hardy tree, with elliptic shaped leaves and micronutrient rich fruit, is threatened by over-harvesting, rise in salinity—a fall out of water diversions in the Ganges Basin, and coastal encroachment and top-dying disease. A July 2018 report in Dhaka Tribune revealed that, “In the last 30 years, 1.44 million cubic meters of Sundari trees, worth 2,000 crore Bangladeshi Taka, have been lost to “top-dying disease.”

 A major timbre-producing tree, it has applications in traditional folk medicine as evidenced by its extensive use for treating diabetes, hepatic disorders, gastrointestinal disorders, goiter and skin diseases by the local people and traditional health practitioners. A number of investigations indicated that the Sundari tree possesses significant antioxidant, antinociceptive, antihyperglycemic, antimicrobial, and anticancer activities.

The species is now on the brink of extinction in West Bengal due to excessive logging in the past for its high value wood and now with seawater rise. “It is very difficult to find a Sundari tree in the Sundarbans as the species has a lower tolerance for saline seawater and there isn’t much high ground left, especially on the Indian part of the Sundarbans. Global warming has not just increased surface temperatures but also the saline content in the seawater,” observes Santhosha Gubbi, IFS, Divisional Forest Officer, Sunderban Biosphere Reserve.

(Rhizophora apiculata/ Gorjon)

In the Bangladesh Sundarbans, illegal logging of Sundari trees continues unabatedly. In a February 2016 article by Habibur Rahman and Andrew Eagle for the Daily Star, highlighted the dark side of the timber industry in the largest floating timber market in Pirojpur’s Nesarabad. 

“Before 1985, Sundari logs were sold openly, but in that year, in response to declining numbers the species was protected, with the felling, sale and transportation of Sundari logs banned. It’s now 31 years later and their sale is yet to cease” – the report stated.

The report also revealed that: “Smugglers use different techniques,” explains one source, “Sometimes Sundari logs are covered with coconut coir, sacks or other cargo to avoid detection. With one cubic foot of Sundari timber selling from 400 Bangladeshi Taka to 1500 Bangladeshi Taka according to size, there is money to be made.”

Rising Salinity

A study by the Indian Institutes of Technology points out that unlike other mangrove species, Sundari prefers extremely low saline condition (5 – 15 psu / Practical Salinity Unit) and hence can act as biological indicator of climate change related to sea level rise. The tree can flourish luxuriantly under low salinity conditions. Physiological studies have revealed that mangroves are not salt lovers, rather salt-tolerant. But excessive saline conditions retard seed germination, impede growth and development of mangroves. When the salinity increases, the species becomes stunted, rare and ultimately disappears. The research shows the adverse impact of salinity on leaf chlorophyll of the species may significantly affect the rate of photosynthesis, as this pigment is an indispensable raw material for running the process. Various studies have shown that a number of mangrove species grow best at salinities between 4 psu and 15 psu and for Sundari, the preferred salinity range is much lower. At 15 psu the plants become acclimatized to salt after one to two weeks of exposure, but at 20 psu the seedlings could hardly adapt.

(Sundari Tree. Bishnu Sarangi/Pixabay) 

Every day, up to 150 species are lost. Every year, between 18,000 and 55,000 species become extinct. The narrative of species loss becomes even grimmer when crucial species like the Sundari starts disappearing from its habitat. Paul R Elrich, wildlife biologist from Stanford University and Gerardo Ceballos, ecologist at the National Autonomous University of Mexico, with other colleagues have revisited their 2015 study, which made global news headlines – “The earth is entering the sixth mass extinction phase.” The revised study, published on June 1, estimates the rate of species extinction to be likely much higher than previously thought. The authors remind us that, “The loss of a species is permanent, each of them playing a greater or lesser role in the living systems on which we all depend.” 

Studying and monitoring species loss in land vertebrates is somewhat a manageable task in comparison to invertebrates and plant life. Species are disappearing even faster than science can study and decipher them. This is an alarm call and a reason why this year the United Nations is putting the spotlight back on biodiversity with the theme ‘Time For Nature’ on June 5, a day marked as World Environment Day to promote global awareness and action for the environment.

Satellite data analysed by Earth.Org paints a dismal picture - the Sunderbans is slowly shrinking. Due to “human encroachment and climate change, the forest has been losing almost 16 sq km of vegetation per year since 1991.” A fortnight ago both the jungle and the city of Kolkata was in the eye of the biggest cyclone in recorded history - Amphan (pronounced as "Um-p un", meaning the sky). The huge storm surge estimated around five metres (16.5 feet) inundated all low-lying areas leaving a trail of catastrophic damages. Sunderbans, a spread of 10,000 sq km, is no stranger to cyclonic storms but the frequency and intensity has gone up in recent years. In six months, the mangrove jungle has been struck twice – by cyclone Bulbul in November last year and Amphan in May this year.

(Sunderban landscape)

Amphan has undoubtedly left behind a deluge of humanitarian crisis (along with the lockdown to curb the COVID-19 pandemic) but what it has done to the natural ecosystem of Sundarbans is yet to be accessed.

Pradeep Vyas, former director of Sundarbans National Park, says: “The super cyclone might have killed and displaced a large number of species which inhabit the delta. From fish to reptiles to mammalian inhabitants a huge number is likely to have perished in the cyclone, however we are not certain of the damage. But I fear the loss of prey, especially wild boar and deer population, might result in a diminishing prey base for the tiger, which in turn can aggravate human-tiger conflict in the region.”

Experts are of the opinion that the loss of human lives and livelihood could have been even more severe if not for the Sundarbans. This unique coastal ecosystem shock absorbs the initial impact of the storm and is said to reduce wind speed by 20-25 kms per hour before it makes inroads towards human settlements along the forest fringes.  Mangroves are natural ecological barriers, resilient to extreme weather events like cyclones, protecting coastal communities from frequent storm surges and reduce long-term deterioration of the inter-tidal zone. However, the long-term effects of climate change could erase this natural protection scheme.  Globally, the mangroves also account for 14 per cent of coastal carbon sequestration.

Among the various reports coming in the aftermath of Amphan is that the vegetation in the peripheral forest has turned yellow due to the excessive saline water dumped by the cyclone. The current nature of water in the numerous river channels in Sunderbans is direct fallout of one of the several environmental impacts of dams on rivers - the slow continuous diminishing flow of fresh water downstream.

(A Tiger in Sunderban delta/Nikhil Devasar)

In 1975, the controversial Farakka Barrage (dam) came up on the Ganga, the “holy river” of India, a few miles before the river meanders in to Bangladesh. Over the years as the fresh water flow reduced because of diversion for agricultural and other developmental needs the sea filled in the void especially in the delta.

Speaking from twenty years of field experience in Sundarbans, Vyas says, “The entire central and western part of the Indian Sunderbans is now a backwater of the sea. The wide Matla River that we all sail to get into the tiger reserve is brackish except for the monsoon months. To my estimate there has been a staggering 95% decline in Sundari trees in the Indian part of the Sunderbans. The few trees, which are still standing, are along the international border with Bangladesh but they are not anywhere close to what a grand Sundari looks like as found on the eastern part of Bangladesh Sunderbans. In the Indian part of the jungle species such as  Dhundul (Xylocarpus granatum), Passur (Xylocarpus moluccensis), Kankra (Bruguiera gymnorhiza) Gewa (Excoecaria agallocha) and Goran (Ceriops decandra) have proliferated and taken over the space left by the Sundari.”

This shift in species composition is also highlighted in Swapan Kumar Sarker’s research where he has witnessed the local extinction or range contraction of many endemics including the Sundari in the Bangladesh Sunderbans in the last three decades.  “I found historical tree harvesting, siltation, disease and soil alkalinity as the key stressors that negatively influenced the diversity and distinctness of the mangrove communities in the Sunderbans.” Sarkar’s work reveals that the Sundari is not also safe in Bangladesh Sundarbans, where ‘top-dying disease’ is wreaking havoc. The affected trees go bald on the top and the stems show signs of swelling and formation of several knots known as “heart-rot”. A 2018 report in Dhaka Tribune revealed that ‘top-dying disease’ has killed 15 per cent of Sundari trees since the 1980s.

According to experts the rising temperatures and increase in salinity have also brought microbial-fungal diseases and insect pests. The past five years have been the warmest with heat records increasing every year since 2015. Researcher Katie Louise Awty-Carroll and team from the Department of Geography and Earth Sciences, Aberystwyth University, UK, has demonstrated through analysis of remote sensing data that there is a 25 per cent negative trend in mangrove cover due to the effect of die-back on Sundari trees. These areas are now at greater risk of decline in the future, especially if extreme events such as cyclones become more common. 

Negotiating one of the several small creeks in the mangrove, somewhere close to Bonnie camp (21°49'50"N, 88°37'24"E), forest guard Amin Chand Mondal ( also in video interview) reminisces of the 1970s and 80s when logging permission was given in different forest blocks for the Sundari. “This in all likelihood was the death knell for the species for its timber was much sought-after for making boats, bridges and houses.” Mondal says that most of the grand old Sundari trees fell to the axe, the ones that survived human greed faced an existential crisis. “There was a time when the Sundari tree was abundant in the mangrove forest, but today spotting it is like looking for a needle in a haystack.”

There are many like Mondal in the West Bengal Forest Department who valiantly guard the almost-impenetrable Sundarbans mangrove, night and day, under difficult circumstances, beating inclement weather and the omnipresent threat of life from wild animals, especially the tiger. They know every little creek and island (which looks the same to an outsider) in this dense forest and have superb eye for spotting –species and poachers, even illegal honey gatherers. They are invariably at a loss, especially the older generation, when a tourist or naturalist inquires after the intangible Sundari. Some of the younger guards have never seen the Sundari except for the small plantations undertaken by the forest department in their outposts. For several years visitors, including scientific experts, have come back from the forest dejected without having spotted the species. It is no irony that the visual signage promoting and depicting Sunderbans - posters, brochures and other paraphernalia - does not even mention the Sundari tree. Instead what we see is the red mangrove (Rhizophora apiculata, locally known as Gorjon) with its extensive aerial prop roots as its signature species.

Mondal adds as an afterthought: “It is still possible to revive the growth of Sundari; saplings can be grown in nurseries and transplanted in the forest. It will be a difficult task for forest guards like me to leave the safety of the boat, negotiate low-lying deep swamp to reach higher ground to replant the saplings, that too in tiger terrain, but if Sundarbans can once again have the Sundari tree back, I can risk my life for it.”

(Ananda Banerjee is an author, journalist and environmentalist. He tweets @protectwildlife)