Get non-human primates to help with afforestation

Non-human primates include loris, monkeys, apes, gorillas, and orangutans. The evolution of the primate group, which includes modern-day humans, started over 50 million years ago. Their evolution and distribution have been largely influenced by global climatic changes, driving some primates to extinction and others to evolve their dietary habits and body size in some way to adapt to these changes.

A recent study published in the journal Nature found that analysing fossil records presents an important finding on the extinction of primate species due to climatic changes. The study finds that Gigantopithecus (Gigantopithecus blacki), the largest primate to ever roam Earth started to decline somewhere between 295,000 and 215,000 years ago, finally becoming extinct. The researchers, by examining the teeth fossils of Gigantopithecus across different time periods, confirmed that their extinction is possibly due to their diet changing from a less nutritious to a more fibrous diet, as their favourite forest foods and water became scarcer with the changing climate. 

This study has an important context for present-day tree planting efforts. Presently, deforestation for growing palm oil and fragmentation of forests due to expansion of roads, mining, and agriculture are driving global primary population decline. The composition of forest trees is also changing due to forest fires, invasive species like lantana, logging, and climate change, thereby affecting the food availability of primates.

India has many endemic primates, which means they are found only in India, like the Lion-tailed Macaque and Nilgiri Langur in the western Ghats and the Hoolock Gibbon, the only ape in India in northeast India. And many of them are listed as endangered, meaning they are likely to face extinction soon. Unlike the projects Tiger and Elephant, there are no conservation programmes targeted at primates. But the current restoration initiatives by the government provide an opportunity to do so. India has committed to restoring about 26 million hectares of degraded land and forest by 2030. 

Primates are one of the most conspicuous indicators of forest health and biodiversity. Take the case of the common Langur monkey, found across India, from the Western Ghats to the lower Himalayas. Yet they are conspicuously absent from the planted forests of eucalyptus, pine, acacia, and teak. Primarily because their diet consists of a variety of flowers, fruits, nuts, and tree bark from over 50 different forest species, which varies across different seasons. 

Restoration programmes and tree plantation initiatives can benefit by considering primate diets and their conservation needs, thus aiming for better biodiversity outcomes through forest restoration.

A study published in a Global Change Biology journal identified 10 golden rules for tree planting, including allowing natural regeneration wherever possible and mix species in tree planting to maximise biodiversity. Natural regeneration, though it takes time, will allow forests to create a mix of tree species that provide flowers and fruits at different seasons, supporting primates and other wildlife. If natural regeneration is not possible, trees that are on the dietary list of primates would be a useful choice. As primates, birds, and small mammals are good dispersers, they will aid in the forestation process. 

Many primate habitats are fragmented due to tea, coffee, and rubber plantations. Creating corridors to link their habitat through tree planting will enhance their movements and benefit other wildlife as well. 

Gigantopithecus becoming extinct was a natural process, but the present extinction of primates will be due to current anthropogenic activities, including climate change induced by the burning of fossil fuels. Forest restoration provides an opportunity to conserve primates, and foresters could make the best use of primatologist knowledge in tree planting and forest restoration initiatives. 

(The writer is a researcher examining the social and ecological impacts of tree planting)