Monsoon forests: the tropics’ little-known lands of extremes

This story is part of the Landscape News series Forgotten Forests.

It was the mud that got to Jacob Shell.

The Philadelphia-based geographer, who was doing research in the monsoon forests of northern Myanmar for a book about working elephants in the region, was well-versed in the experience of heavy rain. There, though, “it’s what the rain does to the ground that’s really striking,” he says. “It turns the ground into this very deep, thick, sticky, viscous kind of mud that in my region we just don’t have.

“It’s like, you step into this mud, and your boot gets stuck, and you have to untie it to get your foot out of it, and then you have to gradually pry the now-empty boot out of the mud!”

Monsoon forests – otherwise known as tropical deciduous forests – are scattered across equatorial parts of Southeast Asia, the Americas, Africa and Australia. Straddling the borders between rainforests and dry areas, they’re characterized by contrast. “It’s a kind of transition zone between the humid tropics and the drier but still-tropical vegetation,” says Yves Laumonier, a scientist at the Center for International Forestry Research.

During the rainy or monsoon season, the forests can experience as much or more rainfall than a rainforest, making them lush and green, filled with lianas (woody vines) and epiphytes (plants that grow on other plants). This seasonal ‘closed canopy’ sees little light reach the forest floor. But when the dry season arrives, the forests transform as most trees shed their leaves to conserve precious moisture, and many woody plants that were shaded by the wet-season canopy take the opportunity to flower and fruit.

The animals that live in monsoon forests have also made interesting adaptations to cope with the seasonal extremes. Shell describes watching a snake moving across the ground in monsoon season: “It wasn’t slithering, it was hopping!” he recalls. “It seemed to be its way of dealing with the awkward stickiness of moving around in the mud. So it was hopping like a rabbit… and it was using some sort of like helix-like mechanical maneuver to do that.” 

For human communities, these environments offer unique challenges and opportunities, too. In the Hukawng Valley of Kachin State in northern Myanmar, roads become impassable in monsoon season, so local people – mostly members of the Kachin ethnic group – use elephants for transportation during that time. In the dry season, the elephants are enlisted to help with logging and extracting minerals such as jade and amber.

Pressure to extract commodities, or clear land for agriculture, is a challenge for monsoon forests across the world. Globally, it’s estimated that less than 5 percent of the world’s forests of this type remain intact; they’re considered the most threatened of all the major forest types.

In the Hukawng Valley, says Shell, younger people in particular seemed to have “an intuitive sense that nature and the forest cover is this unique thing that Kachin state has to offer to the world.” It’s true: the valley is the largest biodiversity hotspot in mainland Asia.

But it’s also where most of the world’s jade, and much of its Mesozoic-era amber, comes from. Spurred by high demand, particularly from China, jade mining “is happening at such a massive scale that you can look at it on a satellite photo,” says Shell. “It’s eradicated several square miles of forest in that area.”

Timber, particularly teak, is another high-value commodity for the area, and illegal logging is commonplace. Some of the forest has also been cleared by Myanmar’s government for industrial agriculture, such as oil palm plantations. The Kachin people have been fighting for independence from Myanmar for 60 years now, and most older community members that Shell spoke to appeared to see the exploitation of the environment as a necessity to fund the fight.

“There was more of an ambivalence, or a sense that the political needs to be prioritized over the environmental,” he says. 

In Indonesia, where Laumonier has done the majority of his research, monsoon forests in the eastern part of the archipelago have been “much more disturbed than the rainforest,” he says, “simply because it was easier for people to come to that climate [than to the rainforests] and do agriculture or animal husbandry or other activities.”

Despite their high rate of degradation, monsoon forests receive much less protection and attention than Indonesia’s rainforests. That’s partly because there are no large areas left to protect, and funding donors are more willing to run projects in bigger expanses of forest such as those in Sumatra and Borneo, says Laumonier. There’s also little research or policy that takes the specifics of monsoon forest ecosystems into account. “For instance, the rules for logging are exactly the same whether you’re in Sumatra or the eastern part of Indonesia,” said Laumonier. “And this is wrong. Of course you cannot have the same type of silviculture in a forest where you have six months without water. So every time they do logging in this kind of environment, it’s a disaster.”

Back in 1988, biologist Daniel Janzen made an impassioned call in a book on biodiversity for conservationists, researchers and policymakers to protect the remnants of monsoon forest that remain. “The dry tropics contain adult remnants of a once thriving forest, juveniles from gradually dwindling seed reservoirs, and waifs from as-yet intact wildlands,” he wrote. “These organisms now stand on a trashed agroscape and will die without replacement.”

Janzen noted that the ‘ordinariness’ of these landscapes – the fact that they tend to have less species diversity than rainforests – seemed to stand in the way of them getting the attention they deserved: “In the headlong rush to conserve diversity, we risk leaving the next generation with a handful of pretty baubles rather than the substance of the tropics,” he wrote.

Small-scale projects to protect and/or restore monsoon forests have since emerged in various corners of the globe, from the Balinese coastline, to the Western slopes of the Andes, to Australia’s Northern Territory. But it’s still unclear whether research, funding and policy will catch up to the importance of these liminal landscapes while they’re still around to save.