Last updated February 13, 2023

Interfacing

There are two main types of mycorrhizal fungi that form relationships with trees: arbuscular mycorrhizae (AM) and ectomycorrhizal fungi (EcM), which both employ different nutrient acquisition strategies and establish different forms of contact their host plants. Arbuscular mycorrhizae penetrate the outer cells of a plant’s roots and facilitate nutrient exchange within the cell membrane space. Nutrients released by saprotrophic microbes are scavenged and acquired by the network. In comparison, ectomycorrhizal fungi grow to surround a plant’s root cells for nutrient transfer through the cell walls. Nutrients are acquired by directly breaking down matter in the environment.

Research indicates that these nutrient acquisition strategies also contribute to the different growth and resource distribution patterns in AM and EcM dominant ecosystems. In resource rich situations, such as in high CO2 conditions, AM fungi will contribute more to plant growth, while EcM fungi will contribute more to mycorrhizal fungal growth. AM fungi also promote the growth of a diverse range of plant species (low host specificity), while EcM largely support fewer, more specific species (high host specificity) resulting in less diverse ecosystems. AM fungi are also more efficient at nutrient cycling and re-uptake, keeping nutrient loss within the network low compared to EcM fungi. These connection, nutrient uptake, and growth strategies result in encouraging very different kinds of ecosystems, each with pros and cons: AM fungi dominant ecosystems are much more diverse, however due to the lower contact surface area and within-plant root cell integration, they are also more likely to introduce pathogens to the network which can be detrimental to their host plants. EcM fungi form more monoculture ecosystems, but due to the enveloping, high surface area contact with root cells through a myceilal sheath, there is more of a protective barrier which generally promotes pathogen-free ecosystems. Generally most ecosystems contain both AM and EcM fungi networks.