This article was originally posted on Nature’s Eyes on Environment blog, part of the Scitable Network. Check it out for more blogs from scientists and students from around the world!
The terraced ridges of rice paddies are an iconic image of the Japanese countryside. Flooded with water, these winding lines of aquatic rice pattern forested hills partially occluded by the cool grays of wispy clouds. The word idyllic has rarely had a better visual description.
But this seemingly timeless agricultural tradition is fading in Japan. And, as if the loss of the industry were not enough, a review  in Science reveals that the vanishing of rice paddies will likely cause a severe loss in the rich biodiversity that used to thrive alongside these farms.
Rice Paddy Riches
Logic in the West suggests that the wild and all its biodiversity is ready to encroach back upon its natural realm as soon as Midwestern farmers leave it. Researchers and ecologists also believe it to be so. Right now, extensive farming of the American heartland is hurting biodiversity and its disappearance would likely revitalize certain species.
The opposite appears to be the case in Japan. According to researchers, rare plants and insects have lived a happily symbiotic life with Japanese farmers and their rice. Scientists are still debating why rice paddies promoted such diversity, but it likely has to do with the banks farmers create that surround the paddies. The banks contain the flooded water in the paddy fields, and farmers long ago began the tradition of planting grasses along these banks to stabilize the soil. This tradition essentially introduced grassland diversity into the environment. Farmers also mow the grasses several times a year, never allowing one particular species to dominate and instead encouraging young upstarts to compete.
Diversity appears to breed diversity. Rare grasshoppers, dragonflies, and plants like the yaburegasamodoki, a relative of the sunflower, are seen in abundance along the edges of these rice paddies. As more paddies are abandoned, however, so may these species move inexorably toward extinction.
A Plummeting Population
Why have so many farmers left their farms and rice terraces? The answer boils down to demographics. The population of Japan is beginning a free-fall descent, predicted to drop from 128 million in 2008 to 86 million by 2060. Of the smaller population, most concentrates in cities, leaving the rural farms and rice paddies behind.
It’s also a matter of diet. The Japanese are succumbing to the temptations known for a long time in the West: heavy carbs! Bread and pasta demand has skyrocketed while rice demand has cut in half since the 1960’s. Households are willing to spend more on these imported goods, leaving little room for rice farmers.
Future trade policies will likely only exacerbate these trends. In particular, the Trans-Pacific Partnership, or TPP, is expected to be approved in the next several years, which will make trade of foreign goods like pasta even cheaper.
Satoyama no more?
The Japanese have a word for the idyllic mountain scene of rice farmers and nature peacefully co-existing: satoyama, meaning “mountain village.” But this harmony will likely disappear over the next few decades as farmers disappear and nature reclaims the rice paddies. This time, instead of diversity being reintroduced, certain species will likely take over while pushing the rare, delicate ones out of the way.
The sunflower mentioned above will likely go extinct. Butterfly populations have declined over the past 40 years. The flooded paddies also provide a wetland habitat which will now vanish. As frogs and other insects move to more diverse ecosystems, predators like the gray-faced buzzard will have a harder time finding food. Aggressive species like the kudzu vine and invasive goldenrod from North America will likely create a stronghold around abandoned farms. Like all ecosystems, resilience is tested after such a perturbation. And, as is the case so often, humans are the cause of the perturbing force.
Can anything be done? Atushi Ushimaru, an ecologist from Kobe University, sums up the pessimism: “I don’t see a solution to this problem,” he says. Demography is a powerful force, and one that is not on the side of biodiversity. Most children of rice farmers have already moved to the city. The tradition appears to be in its twilight.
So often we report on how agriculture and industrialization destroys diverse ecosystems. In the Japanese foothills, mountain communities had developed a time-honored tradition of growing food in a way that buoyed and expanded the natural world. Just as those farmers had created it though, human actions now can take it away, as another earthly ecosystem teeters against the strong winds of change whipped up by our ever-churning civilization.
 Normile, D. “Nature from Nurture.” Science, 351(6276), 908-901, 2016.