The Happening

Aging trees are contributing to pollution in Japan, a new report says. What will save us now?

According to a new study, published in the Journal of Environmental Quality, tree farms in Japan are now leaking nitrogen into nearby watersheds. The culprits, specifically, are cedar and cypress trees.

To be clear, these two types of tree are not inherent polluters. Nitrogen is seeping into the water, because several Japanese cedar and cypress plantations, set up in the 1950s and 1960s as commercial forests, are ill-maintained. A press release for the study explains that increased level of wood imports into Japan has decreased demand for homegrown cedar and cypress trees. So the untended farms are full of densely-packed aging trees. That means that very little sunlight reaches the plantation floor, and so there's very little undergrowth. That messes with the natural forest ecosystem. Per the press release:

Just like in a natural forest, needles fall from the aging trees and accumulate on the plantation floor. This is part of Mother Nature’s way of recycling nutrients…. however, the age of the trees in these plantations means they are growing more slowly. They use fewer nutrients from the soil than younger trees, including nitrogen.

Nitrogen that would normally by sucked up by undergrowth and young, growing trees ends up in nearby streams. And Nitrogen water pollution is bad news. io9 explains:

"Because nitrogen is such a vital nutrient, having an excess of it in the water supply causes a rapid increase in the algae population, which then depletes the water of oxygen. This can literally suffocate the fish living in the water."


It's not clear just how much nitrogen is actually coming from these ill-maintained farms, but the authors note that cedar and cypress plantations make up one-third of all the forested land in Japan. So that's a lot.

UPI notes that some conservationists are trying to solve the problem by thinning out these farms. RIP trees.

Danielle Wiener-Bronner is a news reporter.