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Manganese in soil can turn forests into carbon emitters rather than vaults

New research reveals how excess manganese harms the carbon-storing abilities of crucial northern forests. Up to 30% of the world’s soil carbon lies beneath the ancient trees of the forest. That makes boreal forests critical allies in the fight against climate change.

We picture them as natural superheroes, absorbing carbon dioxide from the atmosphere and safely locking it away for centuries.

But what if there’s a hidden villain in this story, subtly undermining the forests’ heroic work?

The manganese mystery

The recent study from Duke University casts a spotlight on the culprit: manganese.

This often underappreciated element plays a vital role in plant growth, but it turns out manganese’s influence extends far beyond individual trees.

In excess, it acts as a catalyst, speeding up the decomposition of organic matter in the forest floor.

When leaves, fallen branches, and other plant debris decay, they release some of their stored carbon into the atmosphere. This is a natural cycle.

But manganese throws this process into overdrive. The study discovered that over time, high levels of manganese in the soil contribute to the release of additional carbon dioxide – a potent greenhouse gas.

Carbon storage and manganese

“Conventional wisdom is these forests are like a global vault of carbon, where carbon is put into the vault versus taken out,” says William H. Schlesinger, a renowned researcher from Duke University.

But this study throws that conventional wisdom into question.

Manganese acts as a skeleton key, slowly but surely unlocking a portion of that stored carbon, with far-reaching consequences for our planet.

Industrialization and manganese carbon storage

Human activities, particularly industrial operations and the combustion of fossil fuels, have a profound impact on the environment, contributing to climate change and altering natural ecosystems in numerous ways.

One such impact involves the release of manganese particles into the atmosphere. Here’s a deeper dive into how this process unfolds and its consequences:

Industrial emissions and fossil fuel combustion

Industries such as metal smelting and the manufacturing of batteries, as well as the burning of fossil fuels (like coal, oil, and natural gas) for energy and transportation, emit a wide range of pollutants into the air.

Among these pollutants are particles of manganese, a metal used extensively in steel production and other industrial processes.

While manganese is naturally occurring and an essential nutrient for plant and animal life in trace amounts, in higher concentrations, it can become harmful.

Atmospheric transport

Once released, manganese particles can travel vast distances through the atmosphere.

This dispersal is facilitated by wind patterns and weather conditions, allowing the manganese to move far from its original emission source.

Over time, these particles can settle onto the surface of leaves and eventually make their way into the soil, particularly in forested areas.

Impact on forest ecosystems

The accumulation of manganese in forest soils can significantly alter the nutrient balance within these ecosystems.

Forests, especially boreal forests in northern latitudes, play a critical role in the global carbon cycle.

They act as major reservoirs of carbon by storing it in biomass and soil, thus helping to mitigate the effects of climate change by reducing the amount of carbon dioxide in the atmosphere.

However, excessive manganese can disrupt these ecosystems’ ability to sequester carbon effectively.

Long-Term ecological Changes

The gradual buildup of manganese from industrial and fossil fuel emissions over decades poses a significant threat to the delicate balance of forest ecosystems. It can affect not only the soil’s chemical composition and fertility but also the health and diversity of plant and animal life within these environments. Changes in soil nutrient levels can lead to shifts in plant species composition, impacting the entire food web.

Forest carbon, manganese, and time

A dedicated team of scientists carefully tracked changes in boreal forests worldwide and conducted a 14-year experiment.

In China’s Daxing’an Mountains, they deliberately added manganese fertilizer to research plots. The results were concerning.

“It is essential to figure out which factors regulate this huge carbon pool [in boreal forests’ soil], especially given continuous… industrialization,” states Yunyu Zhang, lead researcher on the project.

They discovered that in just four years, carbon storage in the high-manganese plots decreased by a significant 13%.

Urgent action is needed

“There’s no proverbial foolproof vault or absolute forest sink,” Schlesinger cautions.

We have to view our planet holistically, understanding the intricate interactions between nutrients, industrial pollutants, and the ecosystems we rely on.

This manganese study serves as a wake-up call, urging us to investigate these links even more thoroughly if we are to preserve the crucial carbon-storing power of forests.

The forest, it seems, is full of mysteries waiting to be unraveled. The story of manganese teaches us that nature is far more complex than we sometimes realize.

It also shows us that even with the best intentions, our actions can have unforeseen effects. The key is to stay curious, to keep investigating, and to adjust our approach in the light of new knowledge.

Only then can we truly be worthy guardians of our planet’s precious forests.

The study is published in the Proceedings of the National Academy of Sciences of the United States of America.


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