In the monsoons, the swamps, typically located near a central stream, are inundated with freshwater gushing in, creating a unique habitat for a host of species. The hallmarks of the swamps are two tree species, exclusively found in the swamps (a.k.a. endemic), that thrive in the waterlogged conditions: Gymnacranthera canarica (also known as Gymnacranthera farquhariana) and Myristica fatua Houtt. var. magnifica (Bedd.) Sinclair. The former is listed as Vulnerable while the latter is Endangered, according to the last IUCN Red List assessments in 1998—which desperately need updating.

Unlike regular subterranean tree roots, the evergreen trees have evolved to live in the waterlogged conditions of the swamps and feature two types of bizarre-looking roots: knee roots and stilt roots. The former pop out from the ground and are used for exchanging gases while the latter sprout from the main trunk and help support the trees mechanically in the soft and unstable soil. Such aerial roots are common among trees found in tropical mangrove swamps.

Scientists have estimated that barely 250 trees of M. fatua magnifica remained in the Karnataka’s Uttara Kannada district from 1998 to 2000. Myristica swamps in southern Kerala’s Kulathupuzha region have a higher population of M. fatua magnifica compared with the swamps in Karnataka, according to a recent study published in 2018. But G. canarica, showed the ability to tolerate drier swamps that were not perennially inundated and was dominant in both regions. Still, those swamps in Kulathupuzha which were perennially inundated have M. fatua magnifica.

Watershed value and potential to fight climate change

Owing to their ability to hold water all-year-around, Myristica swamps play a crucial role in sustaining water in the streams and groundwater sources. The “swamps act as ‘sponge’ in a landscape,” said T.V. Ramachandra of the Centre for Ecological Sciences, Indian Institute of Science (IISc), Bengaluru, explaining that they help in “retaining the water (during monsoon) and then slowly release to the stream during lean seasons.” Considering the linkages of water sustenance with the swamps, these fragile ecosystems were conserved as sacred by local people during pre-colonial times

In addition, during heavy rains, they help in moderating floodwaters. On the recent flooding of Kerala in 2018, Ramachandra noted that “despite highest rainfall and similar terrain, the regions with Myristica swamps handled the floods, while, locations such as Vynaad and Kodagu (land of greedy politicians and business folks who disrupt the stream network by the construction of resorts and buildings along the natural water path) experienced a high level of damages.”

What’s more, these swamps have the potential to mitigate the impacts of climate change. Ramachandra and his colleagues conducted a study on the ecology of the Myristica swamps of Kathalekan hamlet of Siddapur taluk in Uttara Kannada district of Karnataka. They found that the swampy forests have higher aboveground biomass and carbon storage than neighbouring non-swampy forests. With a higher ability to sequester carbon than non-swampy forests, these relict ecosystems have been “silently helping the globe in the removal of carbon” amid the backdrop of global warming, highlighted Ramachandra.

Read more: New species remain hidden in the myristica swamps of the Western Ghats

Climate change and other threats from humans

A study published in 2016 examined the impact of climate change on the distribution of five species of Myristicaceae in 2050 to 2080 under two scenarios. The models showed that both swamp specialists—Gymnocranthera canarica and Myristica fatua—will suffer from a reduced overall suitable habitat area. While G. canaria is estimated to drop by 1.04 percent in current area, M. fatua will shrink by 1.68 percent under a scenario of rapid economic and population growth till mid-century with a balance in fossil and non-fossil energy sources.

Ravikanth, associate professor at the Asoka Trust for Research in Ecology & the environment and the senior author of the study, expresses concern over the effect of erratic and high rainfall patterns on the regeneration of swampy species. “While floods could result in seedlings (and seeds) being uprooted and being washed away, dry spells, on the other hand, could result in higher mortality of the seedlings,” he noted.

“Both the species require flowing water for survival and for the germination of their seeds,” explained Ravikanth. “Our studies [unpublished] have shown that even a few meters away from the swamp, the seeds have poor germination (less than 20%) and those that do germinate have high mortality rates (almost 100%) in summer (within one year of their germination).”

Although the estimated percentage of reduction in the area of the swampy species is not high, Ravikanth points out a myriad of additional threats: changes in land-use, diversion of water for agricultural purposes and the encroachment of swamps.

The study also reveals that most of the suitable areas of swamps lie outside the protected area network and are highly vulnerable to human exploitation. For instance, the brightly-coloured arils covering the large seeds are locally used as a spice for wild nutmeg. “While the arils of M. fatua are extensively harvested and have a good market, the arils of G. canarica are used as an adulterant. Our recent [yet to be published] study indicated that in many areas of the Western Ghats, the fruits are pre-maturely harvested (due to competition among harvesters). The pre-maturely harvested seeds are not physiologically ripe and do not germinate at all,” revealed Ravikanth. “In fact, even if they harvest the mature fruits, the harvesters tend to throw all the seeds (thousands of them) at one place resulting in poor regeneration.”