Seeing the forest and trees in Nepal

Deep inside Jhapa’s Jalthal forest, a group of us botanists were identifying the diversity of flora in the lowest-lying part of Nepal, only 80m above sea level. In mid-July last year, the heat and humidity in the jungle was oppressive.

At a snack stop near a stream, we heard a loud splash. Thinking it could be a branch fall or even a wild animal, we approached it carefully to find it was a fruit.

On closer inspection, it turned out to be the fruit of a Latahar tree. There were yellowish seeds scattered below the canopy of the giant tree that is a close relative of jackfruit.

Latahar is confined to the moist forests of the eastern Nepal Tarai, and it is too dry for it to grow in the plains of central and western Nepal. I had travelled 500km east from Kathmandu just to see this tree.

Jalthal is a hotspot of Latahar, a forest island in the densely populated southeastern corner of Nepal. This small patch of forest is a natural museum of trees -- one-quarter of the 600 species of trees found in Nepal exist in just this tiny area that is less than 0.1% of Nepal's total forest area.

Latahar (Latin name: Artocarpus chama) is one of those species which looks like a jackfruit tree and belongs to the fig family.  The fruits of Latahar are much smaller than the Jackfruit. The deciduous tree can reach up to 40m in height and forms a round crown atop a clear and unbranched trunk of 10-20m.  The tree is so massive its trunk can measure as much as 5m. 

Ripe fruits are eaten raw and can be pickled or cooked as a vegetable. The dark green leathery leaves are used as fodder for livestock. The tree trunk is good quality timber and supports epiphytic mosses, ferns, orchids and the canopy is home to birds. Forest-dwelling arboreal animals eat the fruits that fall.

Latahar grows in the foothills of Chure and in the remaining forests of Jhapa, Morang and Sunsari districts in the Tarai. It is also found across the border in India, Bangladesh, Bhutan, Southern China, Burma, Laos and Thailand, all the way to Malaysia.

In Jalthal forest, the forest floor is strewn with millions of Latahar seeds in June and July, and the Jalthal forest does not just have scattered mature trees but also natural undergrowth, at least for a brief time.

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The fallen seeds start germinating within two weeks and by September and October recently emerged seedlings are plentiful. But very few survive until the next monsoon as dense seedlings undergo self-thinning over time and many cannot grow under the deep shade of mother trees.

The 6,100-hectare Jalthal forest has over 250 old-growth Latahar trees but they are without progeny to replace them in the future. For a healthy population of tree species, there should be more young trees than old growth.

Latahar degradation is due to human overexploitation and encroachment over decades, which accelerated after the transmigration of Nepal’s mountain population to the Tarai beginning in the 1950s after the eradication of malaria.

Felling for timber and firewood increased, and villagers started lopping off branches and saplings for fodder, and this degraded forest hampering regeneration. The Rajbanshi and Meche indigenous people living in the area say they did not over-extract from the forest, as today.

The Jalthal forest is also threatened by invasive species, mainly Mikania micrantha which forms a thick mat during and post-monsoon discouraging Latahar growth. More frequent forest fires have also taken their toll.

Latahar in Jalthal is a case story of steady and continuous forest degradation, rather than large-scale felling which is not as noticeable. Over time, such disturbance leads to irreversible damage to the ecosystem. 

Sanchahang Limbu of Bishal Community Forest says better fodder management can help protect Latahar trees. People who collect fodder are often poor indigenous communities living around the forest. Providing alternative fodder sources will have dual benefits: improving the livelihood of people as well as forest health.

Indeed, given the nature of Nepal’s rural livelihood, a blanket ban on fodder collection will be detrimental, and better management of forest products can help revive many of the declining tree species.

This means forest management which primarily favours valuable sal timber should be extended to include the entire ecosystem. There should be no incentivising of exotic species plantations at the expense of natural regeneration.

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Lila Nath Sharma has PhD in Ecology from the University of Bergen in Norway and currently works at Forest Action Nepal.