This is the fourth and final (for now) post about forests. This topic just continued to (bad pun warning) branch out on me.
You’ve heard of a negative feedback loop or a death spiral? You’ve probably seen them in your projects. Here's an example: There is pressure to get things done faster, so you have the team work overtime, there is team member burnout. You also try fast-tracking (doing things in parallel that best practice tells you should be done in sequence), leading to further slips in the schedule and increased costs, which causes further pressure to cut corners, do more fast-tracking, more overtime, which causes more slippage …. Yep, you recognize this - a death spiral.
Well, it’s the same thing with ectomycorrhizal fungi.
Yes: ectomycorrhizal fungi are an example of a fungal symbiont – a fungus which coats the outside of root branches of trees, exchanging carbon to the tree, in exchange for sugars. Symbiosis. A win-win situation.
The general term for these fungi are mycorrhizal fungi. Mycorrhizal fungi are those that form a symbiotic relationship with plants. There are two main groups of mycorrhizal fungi: arbuscular fungi (AM) that penetrate the hosts's roots, and ectomycorrhizal fungi (EM) which surround the tree's roots without penetrating them. See below for a photo of this partnership.
From a recent article in Nature magazine, EM fungi, mostly present in temperate and boreal systems, help lock up more carbon from the atmosphere. They are more vulnerable to climate change. You can see in the chart below that the EM fungi live in areas of colder (but potentially warming) climate. They have a much slower carbon cycle, therefore are much better at storing carbon in the ground long-term. AM fungi, more dominant in the tropics, promote fast carbon cycling.
According to the research, 60% of trees are connected to EM fungi, but, as temperatures rise, these fungi - and their associated tree species - will decline and be replaced by AM fungi.
In other words, the types of fungi that support huge carbon stores in the soil are being lost and are being replaced by the ones that spew out carbon in to the atmosphere. And the continued rise will continue that decrease of the longer-term carbon storage – you see it now, I hope – a death spiral.
From a recent article in Nature magazine - If there isn't a reduction in carbon emissions by 2100, there could be a 10% reduction in EM - and the trees that depend on them. The results of this finding can now serve as a basis for restoration efforts such as the UN's trillion tree campaign by informing which types of tree species, depending on their associated mycorrhizal network, to plant in what particular area of the world.
In addition to the article in Nature, a related story on BBC’s Science Hour, entitled “The World Wide Web” (podcast audio here), discusses this in great detail, and in fact, the video below is a great summary.
The interesting side story here is that the fungi that is involved in symbiosis with the trees also allows a sort of tree-internet (a Wood Wide Web) to exist, in which trees are interconnected via the fibers of the fungi. I won’t go into detail, but you really should watch the video below by scientist Susanne Simard, and if for no other reason than comedy, you should follow it immediately with the clip from the movie Avatar.
TED Talk Susanne Simard
I found this fascinating from a science standpoint but also a project standpoint. The mapping project, the trillion tree initiative, the research projects by Susanne Simard – they are all at the intersection of sustainability and PM. If you want to learn more of the science, I provide these additional readings:
An academic paper on the storage capability of CO2 by mycorrhizal fungi
An article describing the Wood Wide Web