A recent study led by Duke University researchers has found that manganese in the soil of boreal forests has a significant impact on their carbon storage capacity. Boreal forests, which are mainly located in cold regions at high latitudes, are estimated to store nearly 30 percent of the world’s soil carbon, making them the largest reservoir of land-based carbon on Earth. The carbon in these forests is primarily stored in the humus layer, which is composed of decomposed leaves and other organic matter.
According to the study, higher levels of manganese in the soil stimulate the decomposition of organic matter in the humus layer, leading to the release of more carbon dioxide into the atmosphere. This discovery challenges the conventional wisdom that boreal forests are a secure carbon vault, as the presence of manganese can lead to the loss of stored carbon over time. This has significant implications for climate change mitigation efforts and the global carbon cycle.
Human activities, such as industrial processes like metal smelting or the combustion of manganese-containing fuels, can release airborne manganese which is later deposited in soils downwind. Along with other activities like burning fossil fuels, deforestation, and land-use changes, these disruptions to the natural carbon cycle have led to an increase in atmospheric carbon dioxide concentrations, contributing to global warming and climate change.
By analyzing data from boreal forests worldwide and conducting long-term fertilization experiments in China’s Daxing’an Mountains, researchers found that the level of exchangeable manganese in the soil determines how much carbon is stored in boreal forest soil. After four years of fertilizing plots with manganese, carbon storage fell by nearly 13 percent, indicating that more carbon was released into the atmosphere. This highlights the importance of understanding the complex interactions between trace nutrients like manganese and carbon storage for developing effective climate change mitigation strategies.
Lead author Yunyu Zhang emphasized the need to predict how these interactions will work in the long term, given the impact of continued industrialization. Further research and action are needed to better understand the role of manganese in soil and air on land-based carbon emissions, boreal forest ecosystems, and climate change mitigation efforts. Schlesinger stressed the importance of integrating approaches to land management and climate mitigation, considering both climate and trace nutrients like manganese in carbon storage dynamics. The study was co-funded by the National Natural Science Foundation of China and the Chinese Academy of Sciences.
