Mushrooms: Capturing Carbon, Saving The Planet

Fungi, including mushrooms, play a crucial role in regulating the global climate. Fungi are nature's recyclers, feasting on dead and decaying plants and animals and transforming them into essential nutrients and elements that plants require. Fungi sequester about 80% of the carbon they intake, and they help soils store more carbon. They are the main regulators of the carbon biogeochemical cycle, which moves carbon—the essential element of life on Earth—between the air, soils, and water. Fungi's ability to sequester carbon in the soil is driven by their symbiosis with plant roots, and they can also slow down decomposition, a natural process that returns carbon from forest soils to the atmosphere.

Fungi sequester carbon

Fungi play a crucial role in the carbon cycle, helping to keep carbon out of the air and mitigating climate change. Fungi sequester about 80% of the carbon they intake, using it to build their hyphae, which extend into the soil. This process helps to offset the release of greenhouse gases into the atmosphere.

Soil is the most significant terrestrial carbon sink, storing more carbon than living things and the atmosphere combined. Fungi are the primary regulators of carbon sequestration in soil, and their presence or absence can significantly impact the amount of carbon stored. For example, soils dominated by ecto- and ericoid mycorrhizal (EEM) fungi contain up to 70% more carbon than soils dominated by arbuscular mycorrhizal (AM) fungi. This is because EEM fungi produce more nitrogen-degrading enzymes, allowing them to extract more nitrogen from the soil, which slows the growth of competing microbes and results in more carbon remaining locked in the soil.

Trees and other plants form symbiotic relationships with mycorrhizal fungi, which help them absorb CO2 more effectively. These root fungi can also slow down decomposition, preventing carbon from returning to the atmosphere. However, climate change and extreme weather events, such as fires, can reduce the abundance of these fungi, decreasing their contribution to soil carbon sequestration.

Human activities, such as burning fossil fuels and the use of nitrogen fertilizers, have also contributed to the loss of ectomycorrhizal fungi in forests, leading to a decrease in carbon sequestration. Restoring these ecosystems and promoting the use of agricultural soils for carbon sequestration could be powerful tools in the fight against climate change.

Mycorrhizal fungi and plant roots

Mycorrhizal fungi are a diverse group of fungal species that are associated with the roots of over 90% of all plant species. The term 'mycorrhiza' is derived from the Greek words for 'fungus' and 'root'. These fungi develop an extensive hyphal network in the soil, which can connect whole plant communities, offering efficient horizontal transfer of nutrients.

Mycorrhizae are fungi that have a symbiotic relationship with the roots of many plants. The fungi commonly form mycorrhizal relationships with plants and are ubiquitous in the soil. Both members of the relationship benefit from each other. The fungi improve the nutrient status of their host plants, influencing mineral nutrition, water absorption, growth and disease resistance. In exchange, the host plant provides the fungus with carbohydrates, which it needs for growth and reproduction, as the fungus does not photosynthesize.

Mycorrhizal fungi can be divided into two major groups: aseptate endophytes, such as Glomeromycota, and septate Asco- and Basidiomycota. More commonly, mycorrhiza classifications reflect anatomical aspects and identify two broad categories: ectomycorrhizas (EMs) and endomycorrhizas. Ectomycorrhizae are also known as sheathing mycorrhizae and are found on many evergreen trees and shrubs. They cover the ends of young roots and only penetrate the cell wall of the cortex. The ectomycorrhizal fungi belong to the class of fungi called Basidiomycetes, which commonly produce mushrooms as their fruiting structures. Endomycorrhizae, such as V-A mycorrhizae, belong to the class of fungi called Phycomycetes, or water molds.

Mycorrhizal fungi play an important role in the carbon cycle. They help soils store more carbon by slowing down decomposition, a natural process that returns carbon from forest soils to the atmosphere. Ectomycorrhizal fungi, in particular, are very effective at this, as they produce more nitrogen-degrading enzymes, which allow them to extract more nitrogen from the soil. This slows the growth of competing microbes, leaving more carbon locked away in the soil.

The impact of nitrogen on fungi

Fungi are essential for life on Earth, and they are recognised as their own phylogenic kingdom. They are major contributors to decomposition and soil organic matter (SOM) dynamics. Fungi are also important in the carbon cycle, the biogeochemical process by which carbon moves between the air, soils, and water.

Nitrogen is a primary nutrient critical for the survival of all living organisms. It is a necessary component of many biomolecules, including proteins, DNA, and chlorophyll. While nitrogen is abundant in the atmosphere, it is often inaccessible to most organisms, making it a scarce resource that limits primary productivity in many ecosystems.

The concentration and availability of nitrogen influence the activity and growth efficiency of saprotrophic fungi. When nitrogen is scarce in soils, fungi have to invest more energy to obtain it, which can result in lower growth efficiencies. Fungi contribute to nitrogen cycling by decomposing organic nitrogen in tissues and releasing inorganic nitrogen back into the ecosystem as ammonia in a process called ammonification. This ammonia then becomes available for uptake by plants and other microorganisms for growth.

Human activities, such as burning fossil fuels and the use of nitrogen-based fertilizers, have significantly impacted the nitrogen cycle by increasing the amount of biologically available nitrogen in ecosystems. This increased nitrogen availability can negatively affect soil fungal biomass and the growth of certain types of fungi, such as ectomycorrhizal fungi, which are important for carbon sequestration in forests.

In summary, the impact of nitrogen on fungi is complex and multifaceted. While nitrogen is essential for fungal growth, too much nitrogen in the form of pollution or fertilizer use can disrupt fungal communities and their contributions to ecosystem functions, such as carbon sequestration and decomposition processes.

The role of fungi in the carbon cycle

Fungi play a critical role in the carbon cycle, the biogeochemical process by which carbon moves between the air, soil, and water. Fungi are nature's recyclers, feeding on dead and decaying plants and animals, and transforming them into essential nutrients and elements that plants require.

Fungi help soils store more carbon. Globally, soil is the biggest single terrestrial reservoir of carbon, containing far more carbon than living things and the atmosphere combined. Fungi are the main regulator of this process. As decomposers, they produce organic materials with very long residence times in the soil.

Most plants have a symbiotic relationship with mycorrhizal fungi: the fungi extract nitrogen from the soil and make it available to plants through their roots. However, one major type of symbiotic fungi can extract nitrogen much more quickly than other types, slowing the growth of competing microbes and leaving more carbon locked away in the soil. Soils dominated by ecto- and ericoid mycorrhizal (EEM) fungi contain up to 70% more carbon than soils dominated by arbuscular mycorrhizal (AM) fungi.

Fungi sequester about 80% of the carbon they intake, continuously armoring their hyphae with mannins and chitin. Mycorrhizal fungi sequester carbon in the soil by assimilating carbon from the atmosphere in their hyphae. They augment the removal of atmospheric CO2 from their plant hosts and use it to build the hyphae, which extend into the soil. This can help offset the release of greenhouse gases into the atmosphere.

Fungi are also important in forest ecosystems, where they help trees absorb CO2. Ectomycorrhizal fungi, in particular, can slow down decomposition, a natural process that returns carbon from forest soils back to the atmosphere.

Fungi and climate change

Fungi play a crucial role in the carbon cycle, the process by which carbon moves between the air, soil, and water. Fungi are essential in helping to mitigate the damages of climate change by recycling and storing carbon.

Fungi, including mushrooms, can exist underground, growing symbiotically with the roots of trees. These root fungi, called mycorrhizal fungi, help forests absorb CO2 pollution, delaying the effects of global warming. Specifically, ectomycorrhizal fungi can slow down decomposition, a natural process that returns carbon from forest soils back into the atmosphere. By forming partnerships with trees, these fungi enhance the ability of forests to keep carbon locked up in trees and soils, preventing it from contributing to global warming.

However, human activities, such as burning fossil fuels and agricultural runoff, are causing forests to lose these vital fungi. Nitrogen pollution from fossil fuel emissions and fertilizers is particularly harmful to ectomycorrhizal fungi, leading to their decline and accelerating climate change.

On the other hand, certain types of fungi can be detrimental in the context of climate change. For example, the fungus that causes coffee rust (Hemileia vastarix) has devastated coffee crops in Latin America, with rising temperatures, rainfall, and extreme weather conditions favoring its spread.

Despite the complex relationship between fungi and climate change, fungi are crucial allies in the fight against climate change. By understanding and conserving these organisms, we can harness their potential to strengthen ecosystems and mitigate the impacts of environmental stressors.

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