How do mycorrhizal fungi help tree roots absorb nutrients?

In the context of temperate forest ecology, mycorrhizal fungi form a mutually beneficial, or symbiotic, relationship with tree roots to enhance nutrient uptake. This association functions through the following mechanisms:12

• Increased Absorption Efficiency: Mycorrhizal roots are significantly more efficient at absorbing dissolved mineral nutrients from the soil than uninfected roots. By extending their branched, tubular filaments—known as hyphae—into the soil, the fungi effectively increase the surface area available for nutrient collection.213
• Nutrient Exchange: This partnership is a two-way street. The tree provides the fungus with essential nutrition in the form of carbohydrates (sugars) produced through photosynthesis. In return, the fungus shares the mineral nutrients, such as phosphorus, and other compounds it absorbs from the soil with the host tree.24
• Structural Integration: Depending on the species, the fungi either form a protective mantle around the exterior of the rootlets (ectomycorrhizae) or penetrate the root cells directly (endomycorrhizae) to facilitate this transfer.134

In some forest environments, these fungal networks can even connect multiple trees, allowing for the exchange of nutrients and chemical signals across the forest community.4