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4 July 2017

Warmer Winters to Have Devastating Effect on Silica

“Silica gets no love,” according to Wally Fulweiler, an Associate Professor for the Department of Earth and Environment at Boston University.

The importance of silica is often overlooked by ecologists and biologists in favour of carbon, but that shouldn’t be the case as the impact of climate change continues to intensify. This compound plays a huge part in sustaining marsh and ocean ecosystems by forming the outer shell (frustule) for diatoms, a form of phytoplankton that houses carbon dioxide at deep-sea levels. These help to regulate the global climate over an extended period of time.

While oceanographers have started to take note of silica’s role for the environment, the same cannot be said for forest ecologists. Their interest in other natural processes has caused them to neglect the compound, and more worryingly the impact of human activity on the silica cycle.

The way the cycle works is through trees which suck up the compound from groundwater stores and then convert them into a biologically available form. This can then go one of two ways; either the trees store it or the silica is returned to the ecosystem where it makes its way into rivers and oceans.

PhD candidate Tim Maguire recently looked into this process and found that trees – or at the very least sugar maples – are far more efficient at taking in silica than was initially believed. He also discovered that the warmer winters caused by climate change are damaging the vulnerable roots of the trees and negatively affecting the availability of silica and its environmental cycle.

In the northeast of the United States, for example, the average temperature in winter is now over 1.5°C warmer than it was in the 1950s, meaning the amount of snowfall has started to decrease. Pamela Templer, who contributed to Maguire’s study, ran an experiment between 2008 and 2012 where sections of the New England forests had their snow cover removed to see the effect it had on plant life. The results showed that the tree roots were actually more protected by the snow cover because they prevented them from freezing.

“We found many negative effects where you take away snow; you freeze the soils and it damages the trees,” Templer said of her experiment. She hadn’t considered the effects it would have on silica until she was approached by Maguire, where they then examined samples of sugar maple roots. The tests showed the roots contained 29% of the silica in the trees, but when damaged by freezing, that dropped by a massive 28%.

These findings could be disastrous for silica supplies in both forests and the rivers that they then feed into. In the case of the former, the compound is needed for giving structure to leaves and protecting against harmful fungi, leaving trees weaker without it. If tree roots are impacted by cold temperatures and freeze, Maguire calculated that there would be reduction of around 31% in the amount of silica usually pumped downstream to rivers and other water supplies.

Although the silica cycle is not going to end with the growing impact of climate change, it’s likely to suffer greatly as a result of it.

James Darvill

James is a passionate scriptwriter and reluctant poet with a talent for the dystopian. When he’s not staying up late watching the Simpsons he’s beating the world at Mario Kart, always with a glass of wine in hand.