Mycorrhizal networks are a major global carbon sink: ecosystems with plants that feed carbon to underground networks store an estimated 8 times more carbon compared to ecosystems with non-mycorrhizal vegetation. Underground fungal networks sequester carbon in three ways. First, fungi use carbon to build rapidly expanding networks in the soil. These networks are connected to plant roots, and act as nutrient highways. Second, sequestered carbon is used to create fungal exudates. Exudates are tough organic compounds that help form stronger soil aggregates, which act as a stable carbon reservoir, reducing erosion rates and maintaining soil structure. Third, sequestered carbon is stored in fungal necromass. Necromass describes underground networks that are no longer active, but whose complex architecture is structurally woven into the soil matrix. Microbial necromass is responsible for up to one-half of total soil organic matter and helps stabilize soils.
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