The ‘true’ body of a fungus is composed of microscopic threads called hyphae, and it has been estimated that the ratio of total hyphal length to root length in ectomycorrhizal fungi can be as high as 100,000:1 in a mature fungal network (Read, 1991). This ability to acquire nutrients 100,000 times more efficiently than tree roots explains why natural forest ecosystems can persist for so long. However, the benefits of mycorrhizal fungi extend beyond just nutrition.

Mycorrhizal fungi are important agents in mediating the fertility, structure, and carbon storage potential of soil. In natural woodlands, young saplings rely almost exclusively on fungal nutrients to establish. In addition, when trees have the right complement of nutrients, their defences against pathogens - including fungal ones - is enhanced.

The structure of the soil itself is affected by ectomycorrhizal fungi, which aggregate soil particles together, allowing it to hold more water and giving it that characteristic ‘loamy’ texture in healthy habitats. This ability to hold water, and the ability of fungal hyphae to reach deep into moisture reserves has profound impacts on overall soil hydraulics, and can confer increased tree tolerance to drought events.

The need for the right ectomycorrhizal fungi is made clear when trees are planted on degraded soils and ex-agricultural sites that are devoid of their fungal partners. Sapling mortality is much higher in these regions, which poses a setback for landowners interested in accelerating woodland and forest establishment. In these regions, inoculating young trees with ectomycorrhizal fungi has been shown to yield the greatest returns.