Mycorrhizal networks

 July 5, 2022

Mycorrhizal networks.

I want to add this additional environmental note to yesterday’s about Terra Preta de Indio. It is another one of those facts that when presented along the traditional research path on the ‘net it doesn’t give you much leeway to do much with it. So let’s stick to facts. 

What we’re talking about with mycorrhizal networks are root fungi that link the roots of plants and trees together in a forest or garden. What this means is that trees in a forest are sharing nutrients, and even resistance to disease, among each other, through this network of root fungi. This has some real applications, both practical and theoretical. 

For instance, some gardeners know that some plants do well to be planted by each other - tomatoes and basil, or strawberries and sage, for instance. A lot of this has to do with mycorrhizal networks: it allows certain plants to “share” productivity with each other, and others, not. They’ve proved this empirically. (I believe the study is Song, et.al. (2010)). Tomato plants in the same pot that are airgapped (that is, their only connection could be through the roots) share resistance to disease among each other when one tomato plant is inoculated with a plant pathogen. That means, the tomato plants are sharing information through their roots about diseases that are present in the area, and also sort of pooling resources for defending against them. “Companion plants” can do this as well, even though they are not the same species. 

It stands to reason that the trees in forests also communicate and pool resources through the root fungi network. And it turns out this can be empirically shown, too. The result is that certain clades of tree species share among themselves in a forest ecosystem through the mycorrhizal networks. And there are actually central trees in this network that give more than they receive, for the benefit of younger trees further away on the new edges of the network, and so on. 

The practical application of this element of mycorrhizal networks to forest management is an age-old practice known as coppicing. They used to do this in medieval forests, i.e. those governed by the Charter of Forests. It stands to reason, that a tree that is cut down is not dead in the roots - because the root mycorrhizal network is also supporting the roots of that felled tree. And you’ll see, often, some new shoots come up out of a stump. What they used to do when coppicing was the prudent common practice, was allow those new shoots to grow, and gather firewood from those new smaller branches. This brings forest management down to a more granular level, of that of the individual tree. And it turns out the smaller branches of trees burn hotter for fuel, and so on. You can still see some old coppiced trees in Europe on the borders of forests. Yew trees, used for bow-making, and so on.