This is the World Organic News for the week ending the 29th of April 2019.
Jon Moore reporting!
Decarbonise the air, recarbonise the soil!
I’m back to the usual format this week. I’m glad so many people enjoyed last week’s diversion with myself being interviewed for the Permaculture Plus Podcast about what we are doing here in Highclere as we run regenerative experiments on small plots.
This week’s first post is from with The Applied Ecologist’s Blog entitled: How to keep the mycorrhizae? The more hosts you leave, the more symbionts you get.
We haven’t looked at this area for some time so let’s dive in.
One of the most important above-below ground interactions is that between plants and mycorrhizal fungi. Acting as symbionts, mycorrhizal fungi are involved in plants’ nutrient uptake and water acquisition as well as protection against pathogens. They also take part in processes at a broader ecological scale: they contribute to plant diversity and community assembly, affect nutrient cycling and are fundamental at ecosystem functioning. Due to their key position at the plant-soil interface, mycorrhizae can be highly affected (both positively and negatively) by any human introduced change in environments.
The depths and extent of the mycorrhizal communities is beyond comprehension, some days. That we have managed to still produce food whilst ripping these apart is quite amazing. The biodiversity effects and community assembly do need a little thought. If we destroy the mycorrhizal communities through, say, clear felling. What pioneer species do we encourage? Are they more fire tolerant or less? Are they the species that thrive in fire affected niches and are therefore happy to burn as part of their propagation strategy? We know so little of these things. If the precautionary principle were applied, I think we would see some long term value.
Of course a cubic metre of wood chips has a value immediately. So to do the mycorrhizal communities. The wood chips’ value can be expressed in dollar terms, the mycorrhizal communities, not yet. It would appear that despite the greenwash of the triple bottom line, it is only ever the dollar value that will be accounted for. After all you can’t tax, yet, implied improvement in biodiversity by not clear felling a forest.
But there are opportunities. The post goes on to talk about retention forestry.
Retention forestry, a practice that has been implemented in forest management since just a few decades ago, is an alternative to clearcutting, by which a portion of the original stand is left unlogged to maintain the continuity of structural and compositional diversity. Human-introduced disturbance provoked by forestry can greatly differ from natural disturbance in terms of effects on the ecosystem. Retention forestry has emerged as a response to the rapid ongoing modification and simplification of forest ecosystems. It is therefore recognized, not only as a way to conserve the structural, functional and compositional diversity of forest ecosystems, but also as a useful tool for the restoration of impoverished or degraded forests. Mycorrhizal fungi are within the organisms that benefit the most from tree retention ( see Rosenvald & Lohmus, 2008).
In much the same way as no fishing zones allow for the rejuvenation of fish numbers so too retention forestry maintains an oasis of underground life intact. It is easier for these underground resources to strike out to repair when they are supported by a strong above ground community. And vice versa for that matter. We separate the above ground from the below but remember they are just one ecosystem. It is for our convenience that we who live above the soil surface and are not plant based make this distinction.
I heard an analogy the other day that seems appropriate at this point. If we accept the Earth is 4.6 billion years old, give or take and we convert that into 46 hours because we can understand that more easily. Then in the last thirty seconds of that 46 hours we humans have removed 50% of the world’s forest cover.
Now this is bad enough but with our growing understanding of the mycorrhizal communities we have also wiped out 50% of this balancing structure within the soils. On the most used soils we see North Africa, once the breadbasket of the Romans Republic and Empire, is now a desert for all intents and purposes. The fertile crescent and the desert lands of Iran and Iraq, once grain producing behemoths now desert.
Could it be that the tree cover removal is not the cause of desertification but that tree cover removal is cause of mycorrhizal death and it is that death which leads to desertification? Of course both explanations require the removal of tree cover. The point I’m attempting to make is that we may have a little more time up our sleeves. If we can re-establish the tree cover quickly, the mycorrhizal communities, especially if there was some retention forestry going on, those underground powerhouses of plant production may be restored and extended into desert areas over time. We need to draw a line. The Chinese have been attempting to stop the expansion of the Gobi, the green wall of Africa is a similar attempt to stop the southern expansion of the Sahara. Once stabilised, I’m certain we can then focus not so much on the tree cover which has been the focus since last century but on the underground resources. For it is here that I think we can affect permanent change.
A forest is not a static thing. Individual trees come and go. The make changes as fire events and rainfall variations occur through time but the forest remains. That 50% loss of tree cover mentioned above has been playing on my mind ever since I read it. It is both quite depressing but equally hopeful. There are any number of ways to produce food from trees. I discussed the 1 million hazelnut project in the US of A a few episodes back. Just about any oil would be better than palm oil with its tendency to cut down rainforest to grow a mono crop but it is in the temperate regions that most deforestation has occurred. And it is in these areas where tree planting will have massive impacts.
Not every tree will need to produce human food but I think a permaculture type approach where each tree provides at least three benefits would be a good place to start. So an Oak tree would provide: shade, mulch, acorns for pig feed and eventually timber. We can extend this out into other areas but the principle is straight forward enough.
Replacing as much of that 50% we have removed and converting the remaining agricultural land to regenerative models will have us well on the way to reversing the build up in the atmosphere of too much CO2 too quickly. Toss in the continually falling prices of solar PV and wind generation and we are heading towards a situation where we will be decarbonsing the air and recarbonising the soil.
And on that note I’ll draw this episode to a conclusion.
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Thank you for listening and I’ll be back next week.
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How to keep the mycorrhizae? The more hosts you leave, the more symbionts you get.