​Trees and their keepers

By B P Ravi

The lush green Myristica swamps in Uttara Kannada give visitors the impression that the Western Ghats are thriving despite the pressures of development. But seasoned observers are already noticing signs that portend major changes ahead.

The Kathlekan Myristica Swamp forests are synonymous with the rich heritage of the Western Ghats. For Venkataramana Nagu Naik of Mavinagundi village, who has been serving the Karnataka Forest Department as a watcher for 32 years, the swamps are a second home. He knows their micro-ecosystems intuitively, and he expresses his expertise in everyday language.

During a recent visit, Naik spoke of an unusual development in the life of the Dhuma tree (Dipterocarpus turbinatus), native to tropical semi-evergreen and wet evergreen forests of India and Southeast Asia. Over the years, both seed production and natural regeneration of the Dhuma have declined. 

When asked, he said he does not know the precise cause but pointed to extreme summer heat, prolonged dry spells, and higher annual temperatures as possible reasons. What is troubling, he adds, is that the change is occurring at a time when the forests otherwise appear to be in good condition. Dhuma and other species have recovered well after years of strict protection, with forest fires almost entirely controlled.

Globally, research has shown that flora and fauna are behaving in unusual ways under the stress of extreme temperatures and shifting weather patterns driven by climate change. The International Union for Conservation of Nature notes that of 3,531 plant and tree species assessed in India, 158 are critically endangered, 286 endangered, 238 vulnerable, and 98 are near threatened. The status of 306 others remains unknown due to insufficient data. Extreme weather, invasive species, and other compounding factors of climate change are likely to push more species towards risk.

I took Venkataraman’s observation to R Vasudeva, Dean of Forestry College, Sirsi. He suggests several factors, from fruit-eating insects (weevils and beetles) eating the Dhuma seeds after they fall to reduced seed production, for the poor regeneration of Dhuma. His observation on the role of aphids (sap-sucking insects) opens yet another window: studies have shown that pests are thriving in warmer, more humid conditions created by climate change. 

Seed production in evergreen forest trees is largely through insect pollination (‘entomophily’).

It is unclear whether the pollinating insects of Dhuma themselves are affected by extreme weather or if their reproduction cycles are now out of sync with the tree’s flowering.

Another factor could be changes in primate behaviour. A decline in their arboreal activity (lion-tailed macaques and langurs) and an increase in land usage may have reduced the movement of pollinating insects, which once flew from tree to tree to avoid being the next meal of the LTMs or langurs. As Venkataramana notes, insect activity increases when langurs and LTMs are present in the canopy, boosting cross-pollination and seed production.

Evergreen forests, Myristica swamps and shola ecosystems are highly complex. Researchers are only beginning to grasp their intricacies, which may remain beyond our full understanding. In this background, it is imperative that disturbances to these systems be kept to a minimum. 

Though large-scale diebacks have not yet been reported in the Western Ghats, troubling signs are emerging. In 2020, over 150 jala (Shorea talura) trees died due to a sudden pest attack. There are also reports of Myristica species (Ramapatre and bitter nutmeg) near Castle Rock in Uttara Kannada being affected by increased pests, with some trees succumbing to hydraulic shock. Elsewhere, Terminalia tomentosa (Karimatti) near Bhagawthi in Halyal division has suffered heart-rot disease, while Emblica (Nelli) and mahogany are battling shoot-borers.

Thus, it is clear that pests and diseases are increasingly affecting tree growth and productivity. There is yet another group of silent killers harming the native ecosystem -- invasive species like lantana, mikenia and senna (Cassia spectabilis) are spreading rapidly in Bandipur and other protected areas.

What is needed is regular ecological monitoring and vulnerability assessments of forest tracts, with closer collaboration between field staff, research institutes and universities. Training and sensitisation of frontline personnel should extend beyond trees to include herbs, shrubs and medicinal plants, many of which are at severe risk but receive little attention.

These developments underscore the urgency of assessing the impacts of development projects in fragile ecosystems. Wildlife sanctuaries and national parks were created to ensure better protection for the native species.

We are already in the midst of the seventh extinction, though few notice it. Dipterocarpus bourdilloni, the cousin of Dhuma, has become a critically endangered species. Next in line may be Dhuma and others. The time has come to treat these areas as no-go zones.

(The writer is an IFS officer in Karnataka)