Where did the 'endangered' Nilgiri wild jamun disappear

Notably, the journey to one of Tamil Nadu's remotest forests begins where most roads end.

Key points

• The 2023 IUCN assessment estimates that there are fewer than 700 mature individuals of Syzygium calophyllifolium left in the wild, spread throughout just 13 subpopulations in five montane landscapes.
• Renee Maria Borges, evolutionary biologist and professor at the Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, notes it would be as of climate change.
• One of the two metapopulations of Nilgiri Tahr is in Western Catchment Area and this landscape that primarily consists of montane shola forests is particularly fragile.
• This person has worked in the Western Catchment Area for the last 10 years, the absence of flowering this year is striking.
• A 15-year record from Uganda's Kibale National Park discovered that solar radiation and ENSO assisted predict fruiting patterns.

In practice, a four-wheel vehicle took us till Parsons Valley and from there, we went on a bike to the Western Catchment Area. The last stretch had to be covered on foot, trekking through steep slopes at elevations above 2, 000 metre.

After hours of travel in bone-crushing cold, mist and solid winds, we finally reached the hill slopes where hundreds of Nilgiri wild jamun (Syzygium calophyllifolium) grow.

Although the fruiting season has almost come to a close, I could not find even one ripened Nilgiri wild jamun. We searched hundreds of trees. Forget regarding fruiting, we did not see even the flowering. Stunted budding was noticed in just a few trees.

For a tree that the IUCN Red List has already classified as Endangered, the absence was tough to ignore.

Meanwhile, the 2023 IUCN assessment estimates that there are fewer than 700 mature individuals of Syzygium calophyllifolium left in the wild, spread throughout just 13 subpopulations in five montane landscapes. The population is declining. The Nilgiri and Agasthyamalai landscapes together account for 72% of the species' population, making the high-altitude forests of the Nilgiris particularly significant for its survival.

Meanwhile, the IUCN assessment notes the species is chiefly identified in montane evergreen forests, generally between 1, 000 metre and 2, 300 metre, and has an estimated area of occupancy of just 56 sq km. It records a continuing decline in mature individuals as well as in the area, extent and quality of its habitat. So this was not merely the absence of fruit. It was the silence of an ecological event that simply never happened or observed so far. Whether this is a cyclical phenomenon or whether something more serious is at play remains a question.

Is it linked to warmer years, El Nino years or poor monsoon? Incidentally, 2026 is one of the warmest years and a super El Nino is at present taking shape. The area additionally experienced unprecedented ground frost before the fruiting season. Could that have affected the trees? Could changing weather conditions have affected pollinators? And if the flowering and fruiting cycle is disrupted repeatedly, what happens to the animals that depend upon the tree? The IUCN itself lists February to May as the species' flowering and fruiting period. Phenology – the timing of flowering, fruiting and other recurring biological events – is increasingly recognised as a sensitive indicator of environmental change. Scientists say plant reproductive cycles are influenced by environmental cues and are often synchronised with pollinators and seed dispersers.

M G Ganesan, former director of Project Nilgiri Tahr and current deputy director of Mudumalai Tiger Reserve, notes Mukurthi National Park is a prime habitat for Tamil Nadu's state animal Nilgiri Tahr.

"One of the two metapopulations of Nilgiri Tahr is in Western Catchment Area and this landscape that primarily consists of montane shola forests is particularly fragile. Nilgiri wild jamun is an indicator species of ecological health and discovered only in this ancient shola landscape. Every year, it is customary for me to visit there and relish eating the fruit, but this year I haven't seen a single tree with the fruits. This is not confined to western catchment alone, but observed in the entire Nilgiris landscape." Climate clock falls out of sync.

For anti-poaching watcher G Arun Kumar. This person has worked in the Western Catchment Area for the last 10 years, the absence of flowering this year is striking. He remarked there was no flowering and felt that the poor monsoon, high winds and heavy misty conditions could have a direct correlation with the failure. "Climate change is affecting the forest, " he remarked, pointing to the changing conditions being experienced in the high-altitude landscape. But scientists caution that one year's failure cannot automatically be attributed to climate change.

Anita Varghese, director (biodiversity), Keystone Foundation, remarked numerous trees that produce fruits in abundance, such as amla and mango, have a resting period after mass flowering and fruiting. Nilgiris wild jamun could additionally show such a phenomenon.

While stressing that the trees need to be observed again next year, "That could be the phenomenon, " she remarked. If the failure repeats, climate stress could become a stronger possibility, particularly since this year had poor rainfall. Anita remarked the relationship between climate and flowering can additionally involve a time lag. A drought or rainfall deficit in one year may affect flowering in the after year. "This year's drought will reflect on next year's flowering, " she remarked. That makes the next flowering season particularly significant. Anita additionally stressed the need for regular monitoring as phenological changes can be subtle but significant indicators of climate change. According to She, changes of even a couple of weeks in the timing of flowering can have ecological consequences.

Renee Maria Borges, evolutionary biologist and professor at the Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, notes it would be as of climate change. "We are seeing such disruptions across the world, but without long-term studies it would be difficult to draw conclusions." According to field personnel who have worked in Mukurthi for a number of years, fruiting has generally been observed every year. While flowering was virtually absent, some staff with almost a decade of experience in the landscape additionally documented that they had never seen such a widespread absence of flowering and fruiting.Throughout hundreds of trees examined, only a handful indicated immature fruit. There were no obvious signs of disease or widespread tree mortality. Meanwhile, the trees appeared healthy.

Warning hidden in the missing fruit.

For context, the disappearance of the fruit becomes more significant when seen against the species' already precarious conservation status.

Dr B Subbaiyan, senior research fellow with the Tamil Nadu Forest Department's Project Nilgiri Tahr and a plant taxonomist, notes the species occupies the higher sholas and plays an notable ecological role. A failure in flowering, therefore, means much more than the loss of one season's crop. It potentially affects every species that depends upon it. Project Nilgiri Tahr observations show that the tahr is primarily a grazer but can become more of a browser during periods when grasses dry up. Field observations have recorded Nilgiri tahr feeding on young leaves and shoots of woody plants. Whether its fruit is an significant nutritional component of the tahr's diet, even so, remains insufficiently documented.

Wildlife biologist K Manigandan, associated with Project Nilgiri Tahr, notes documenting the flowering calendar of key food plants has become increasingly notable since climate-driven shifts may not be immediately visible in wildlife populations. "Trees can provide some of the earliest warnings of ecological change. If flowering fails repeatedly, the consequences could ripple through the entire shola ecosystem long before they become obvious in animal population counts."

There is enough research done to establish the fact that plant reproduction is directly linked to climate. At Kalakad-Mundanthurai Tiger Reserve, long-term observations discovered fruiting could follow rainfall with a lag of concerning two months. Research additionally identified reduced pollination success in disturbed areas, partly since of fewer visits by mammalian pollinators and the loss of unpollinated flowers to infections after unseasonal rain.

International studies show the same complexity. A 15-year record from Uganda's Kibale National Park discovered that solar radiation and ENSO assisted predict fruiting patterns. In Japan, centuries of flowering records have demonstrated a relationship between cherry flowering and March temperatures. Climate change can additionally disrupt the relationship between plants and their pollinators. If flowering shifts but pollinators respond differently to temperature or rainfall, the period during which both partners overlap can shrink. Forest has no memory, unless we record it.

This is not the first time Mukurthi's management records have flagged declining fruit availability. The decades-old Mukurthi National Park management plan, accessed by TNIE, had already recorded a similar concern involving another wild fruit almost two decades ago. It talked regarding fruit production of Rhodomyrtus tomentosa, a wild gooseberry. "This fruit production during the month of December-January has considerably reduced. This is causing a shortage of food for herbivores and birds in Mukurthi. In depth research on this needed to protect and conserve this keystone species, " the plan prepared in the 2000s reads.

In 1990, Renee Borges proposed to investigate plant-animal interactions in the Western Ghats, with Mukurthi identified as a potential long-term research site for pollinator behaviour, breeding systems and mutualistic relationships, but the research never took off.

More than two decades afterwards, there is still no continuous, long-term dataset tracking Syzygium calophyllifolium against rainfall, temperature, frost, soil moisture and pollinator activity. The IUCN assessment itself records that there is no systematic monitoring scheme for the species. When fruits mature and whether the cycle changes during drought or unusually warm years, there is no reliable phenology calendar showing when the trees normally flower, how long flowering lasts. And there is little information on the specific pollinators responsible for the tree's reproduction in the high-altitude sholas.

"That absence of data has now become as worrying as the missing fruit itself, " notes Ganesan. One poor year may simply be a natural resting period. Two consecutive failures would demand closer scrutiny. Repeated failures over a number of years could signal something much more serious and hamper the forest regeneration.That is why scientists and field managers agree on one thing – the trees need to be watched.The flowering of selected trees should be recorded every year, along with rainfall, temperature, frost, soil moisture, flowering intensity, fruit set, fruit maturation and pollinator activity.

In short, where did the ' endangered' Nilgiri wild jamun disappear is the central thread here, and readers can expect follow-up reporting as the picture becomes clearer.