Mycorrhiza is a symbiosis between fungus and plant where the fungus hyphae penetrate the roots, resulting in a favourable nutrient exchange for both organisms. Fungi that form mycorrhiza are usually bound to one or a few specific plant species, and the fruiting bodies are only found near these. Most mushrooms you pick in the forest are arbuscular mycorrhizal fungi(AMF) and ectomycorrhizal fungi(EMF). The Yellow Chanterelle is an ectomycorrhizal fungi, which explains why no one can grow the prized delicacy. The symbiosis is too complex to recreate [1].
The fungi’s thin threads of hyphae create a dense web through the soil where they penetrate. A single fungus can spread over several square kilometres over several hundred years, forming a web that holds an entire forest together. A teaspoon of forest soil can contain several kilometres of hyphae [2]. In fact, under every step you take in the forest, there are about 48 miles of fungi with all their branches. And this is true worldwide, even in the desert and certain Arctic regions. [3].
‘The trees in a forest are often interconnected by subterranean networks of mycorrhizae, fungal stands that inhabit tree roots. The mycorrhizal symbiosis enables the fungi to forage for mineral nutrients in the soil and deliver them to the tree in exchange for carbohydrates. The mycorrhizae may form fungal bridges between individual trees so that all the trees in a forest are connected. These fungal networks appear to redistribute the wealth of carbohydrates from tree to tree.” [4]
How trees benefit from mushrooms:
- Nutrient Absorption
Fungi act as extensions of tree roots and can access nutrients, especially phosphorus and nitrogen, that are difficult for trees to reach on their own [5]. - Water Supply
Through their network of hyphae, mycorrhizal fungi play a key role in improving water availability in trees. As water becomes more accessible, trees are more able to cope with drought [6]. - Communication
Mycelium communicates with electrolytes and electrical impulses like our brains [3]. The trees use these signals to feed and talk to each other, exchanging information about hazards such as drought and insects [2] Plants also recognise their offspring in this way, allowing the mother tree and baby plant to communicate with each other. For example, suppose the mother tree knows that there are insect pests nearby and that she is in danger. In that case, she increases her competitiveness for her children, using mycelium so that they reproduce further away [3]. - Protection against Pathogens
Fungi act as a line of defence against harmful pathogens in the soil. They compete for space and nutrients, helping to protect trees from potential damage [7]. Still, they can also protect more specifically by providing plants with antibiotics to defend against parasitic attackers. This cooperation is so widespread that up to 85 per cent of all plants on Earth today need a fungal buddy to thrive [8].
How fungi benefit from trees:
- Carbohydrates
In exchange for nutrients, the fungi get back carbohydrates that the trees supply from their photosynthesis [8]. - Protection
Fungi benefit from the protective environment of the trees underground that prevents external influences [7]. - Propagation
Fungal spores can spread more efficiently through the tree’s root system, favouring the fungi in their reproduction [9].
Even shrubs, grasses, and all plant species have similar communication benefits to trees. But through plant breeding of the crops we grow today, they have largely lost the ability to communicate above and below ground. They have lost their natural defences, leaving them vulnerable. This selective breeding is one of the key factors behind the widespread use of pesticides today [2].
Sources
- Nature & Culture – Photographer Oliver Karlöf
- Good Reads – Peter Wohlleben – The Hidden Life of Trees
- Louie Schwartzberg – Fantastic Fungi Film
- Braiding Sweetgrass by Robin Wall Kimmerer – Milkweed.org-Braiding Sweetgrass
- New Phytologist – Mycorrhizal ecology and evolution
- ScienceDirect – Mycorrhizal Symbiosis
- Nature Communications – Mechanisms beneficial plant–fungus interactions
- Marcus Rosenlund (2022) – The Huge Small Life
- New Phytologist – Observations on the mycorrhizal status of alpine plant communities
April 2023, TÄNKOM | Revised May 2025 RETHINK
