Forest ecosystems depend on the symbiotic relationships between trees and fungi, which form complex networks of mutual benefit.
However, climate change and its associated effects, such as warming, drought, and fire, may disrupt these networks and threaten forest health and function.
The role of ectomycorrhizal fungi in forest networks
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One of the most important groups of fungi that associate with trees is the ectomycorrhizal fungi, which colonize the roots of many tree species in boreal and temperate forests.
These fungi acquire carbon from their tree hosts and provide them with nutrients such as nitrogen and phosphorus.
They also form underground threads, called mycelia, that connect different trees and facilitate the transfer of water and minerals.
These networks enhance the resilience and productivity of forest ecosystems, as they help trees cope with environmental stressors, such as nutrient limitation, drought, and pathogens.
Ectomycorrhizal fungi are diverse and specialized, meaning that different species of fungi prefer different species of trees.
This results in a mosaic of fungal communities across forest landscapes, reflecting the variation in tree species composition, soil properties, and climate conditions.
The diversity and specificity of ectomycorrhizal fungi are important for maintaining the stability and function of forest networks, as they allow for complementarity and redundancy among different fungal partners.
As temperatures rise, the fungi that form these networks may become less effective at providing nutrients to trees and other plants.
This is because warming may alter the activity and composition of soil microbes that decompose organic matter and release nutrients into the soil.
Warming may also increase the carbon demand of the fungi, reducing the amount of carbon available for their tree hosts.
In addition to the direct effects of warming on forest fungi, there are also likely to be indirect effects caused by disturbances such as wildfires, droughts, and insect infestations.
These disturbances can disrupt the networks of fungi that support forest ecosystems, leading to further declines in forest health and productivity.
For example, wildfires can destroy large areas of forest vegetation and soil organic matter, reducing the habitat and resources for ectomycorrhizal fungi.
Droughts can reduce the water availability and increase the water stress for both trees and fungi, affecting their growth and survival, while insect infestations can damage or kill trees, reducing their carbon supply for ectomycorrhizal fungi.
The combined effects of warming and disturbances may result in major shifts in the composition and structure of ectomycorrhizal fungal communities across forest landscapes.
Some fungal species may be more sensitive or resilient to these changes than others, depending on their ecological traits and preferences.
For example, some fungal species may be able to tolerate higher temperatures or lower moisture levels than others.
Some fungal species may be able to colonize new tree hosts or new habitats than others. These changes may affect the diversity and specificity of ectomycorrhizal fungi and their networks, altering their function and resilience.
