A few of us have been discussing, among other things, soil fertility, pastoralism, deforestation, reforestation, agriculture (of course) and permaculture-type solutions for restoring the ecologies impoverished by this culture over on this Leaving Babylon thread. Here’s my most recent contribution on the topic of soil fertility vs. conservation:
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I’ve been thinking lots lately about this issue of soil fertility. On the one hand we’re living through a period of extraordinary fertility thanks to the nitrates and phosphates in petroleum-based fertilisers – ‘more atmospheric nitrogen is fixed by man (as fertilizer) than by all natural sources combined’ (Ken Thompson, No Nettles Required, p.160) – and all gardening and farming is geared towards maintaining or increasing this. And on the other hand we have a legacy of plant and animal species uniquely adapted to the impoverished soils resulting from hundreds/thousands of years of intensive, organic farming, grazing and forestry; a biodiversity that dies out when the soils get too fertile or specific management practices are discontinued. Here’s Michael Allaby writing in the Woodland Trust’s Book of British Woodlands:
The trees that are coppiced regenerate and go on regenerating for a very long time: far from injuring them, coppicing seems to extend their lifespans, so they become an almost perpetual source of wood. Chemically, the wood is composed of substances obtained from the air and soil, like any part of any plant, and cropping removes those substances. Livestock grazing among the trees returned some plant nutrient, but they, too, were removing vegetation by their grazing. The overall effect is a slow but steady export of plant nutrient and a decline in the fertility of the soil. This makes it sound as though the coppicing system is harmful, but harmful to what, or whom? Some plants are better than others at exploiting rich supplies of nutrient. Feed them well and they grow vigorously and, in relation to the plants around them, aggressively. On a fertile soil, therefore, the natural succession by which plants colonise an area will proceed fairly quickly to a situation in which a small number of aggressive species dominate the vegetation.
On a less fertile soil this cannot happen, because the aggressive species are denied the nutrients they need for more vigorous growth. This allows the less vigorous species, with more modest requirements, to thrive. The final result is a great diversity of plant species. The ecological rule-of-thumb is that the greater the fertility of the soil, the fewer plant species will establish themselves on it; and if you prefer a great diversity of species you need a poor soil. Over the years coppicing produces poor soils, and so coppiced woodlands tend to have a rich diversity of plant species. The greater the diversity of plant species, the greater will be the diversity of animals feeding on them, and since the arrival of herbivorous animals is followed by the arrival of predators and parasites of those animals, the entire ecosystem is enriched. (p.106)
So what direction do we pull in? Obviously the petro-fertiliser era is a blip which is going to end in short order, yet I’m less-than-convinced about the longterm viability of the systems that preceded it. Intentionally working to impoverish the soil? Surely sooner or later that will starve the ecosystem to death (although I’m not aware of any coppice rotations that have been stressed to breaking point in this way, even when supplying charcoal for industrial purposes). I think I agree that we have a responsibility to do right by the species we’ve in effect provided the selection pressure for over all these centuries of domesticating the landscape, whether that’s helping them adjust to the changing circumstances or, if that’s not possible, allowing them to die out with dignity. But I think the conservationists are wrong about greater fertility equating to lesser diversity. Maybe this would be the case in the short term, but after a while I expect it will simply be a different kind of selection pressure leading to an explosion of diversity in the more nutrient-hungry plants. How many different hybrid forms of Bramble, Nettle & Dandelion are there already in existence?
Fire-setting is another case in point. From what I’ve read it sounds like N American Indians burned grasses and forest understory purposefully to release the nutrients locked up in the standing dead plants, changing them into a form that was bio-available to the herbs, shrubs and annuals that would be growing on that spot by the next season. This was also an active selection for plants that provided edible, medicinal and other uses for the Indians (and, I assume, for the wildlife they shared the habitat with). It would be interesting to know the mix of woodland plants in Paleo/Mesolithic NW Europe – whether fire management caused this to differ in a similar way. A local conservationist has told me to look for Nettles and Brambles growing in places where our group had previously set fires in old coppice woodland, due to the nutrients released in the wood ash.
Over all it seems to be the case that humans are associated with enriched fertility in soils. That’s one line of archeological evidence for habitation by prehistoric man – at least in Europe you find seeds or pollen grains of Nettle, Plantain, Goosefoot and other associated ‘weeds’. We pitch camp somewhere for the season, eat, shit, do some burning and maybe a bit of gardening before moving on. My best nettle crops have come from places disturbed by people (the very best being where those people fenced off special areas in parkland for their dogs to come and do their business in the times before the ubiquitous small black plastic bags – mmm, dog poo nettles…) Anyway, the main problem with coppicing and other woodland management seems to be the same old civilisational problem of exporting resources far away from their point of origin. If people lived in the woods, building homes, cutting fuel, crafting necessary artifacts from the trees around them, and letting it all rot down on site, I think that could lead to a thriving & enriched ecosystem, supportive of a wide variety of plants and animals.
Tags: biodiversity, conservation, coppicing, ecology, fertiliser, fire management, soil fertility, woodland
June 25, 2012 at 8:05 pm |
Now you’ve thrown in another facet that confounds. Man, it’s getting so complicated. Low fertility good sometimes? Gosh darn.
I’ve been wondering what would happen in arid eastern Colorado, if humans focused not on irrigation, but rather on rebuilding stable humus in the soil. Would that alter the prairie, bring in different plants, maybe more bushes and trees too? On the other hand, I am more inclined to think that it would bring the landscape back to what it was when the bison still roamed, and the vegetation was much more lush, though still grassland mostly. The stuff one sees on rehabilitated ranches in the southwest here, where the grasses just go nuts, and the willows and other bushes get more plentiful.
Thanks for the jolt!
July 6, 2012 at 6:13 pm |
About 15 years ago, there was a devastating ice storm that knocked down millions of trees in the forests of eastern Ontario and western Quebec. As they’ve rotted down they become ‘nursery trees’, and enriched the soil of the forest floor. Now I’m no botanist, but it doesn’t look to me as though the diversity has suffered any, in fact things like ginsengs and bloodroot seem to be making a comeback, and I can tell you many bird and animal species are flourishing again, now that the forests are ‘worthless’ for logging. The mycellium must be extraordinarily happy underneath all that rot. So I’m confused.
If these forests had been ‘managed’, ie, the deadwood hauled out, how would that ensure more diversity than what’s been occurring naturally?
Working to impoverish soil? The idea is unsettling to me.
So is the idea of needing to return areas of land back to their ‘natural’ state – land evolves all the time. Live with beavers and you learn it can happen quite quickly. Wetlands are incredibly diverse, is their soil not considered fertile? I’ve had swamp muck spread on my garden, that was some good dirt! As the beavers move their dams and change the land again the wetland dries out to meadow then back to forest and on it goes.
So I’m having trouble wrapping my head around this idea of fertility = less diversity. It may be politically incorrect to point this out, but the areas here that have been logged (although not clear cut) and *not replanted*, just left to their own devices, stumps and debris left to rot, are healthier than those that were managed according to human standards, ie planted with “desirable trees”. The managed areas end up a mess, susceptible to forest fires; the soil can’t hold moisture because it lacks the *fertility* that comes with gradual decay/growth cycles. Our national parks are a disgrace in that way…
We humans are always in such a hurry to tinker
Mind you, I may be showing my ignorance here. I’m not a scientist.
July 13, 2012 at 3:36 pm |
Usual apologies about delay. I suck etc…
@LG – not good/bad, just different. As ever you get some winners and some losers. There are particular plants that thrive in the most extreme environments – hot, cold, arid, waterlogged, even areas polluted by industrial toxins – but that doesn’t argue for creating those conditions everywhere & all of the time. I’d guess over all, though, that greater fertility is better for the totality of life than less.
That said, it seems like excess fertility introduced from outside the closed system can cause the balance to fluctuate wildly in a way that only benefits a select few (presumably until things settle on a new balance). Here’s Ken Thompson discussing the question of why rare plants seldom show up in peoples’ gardens:
@Christine – interesting. You’re talking about pine forests/plantations there, I presume? As far as I know it’s only the broadleaf species that respond to coppicing, so I’m guessing your ‘nursery trees’ sprang up from seed. Assertions about coppicing favouring biodiversity over here don’t tend to mention mycelium or the quality of the soil, but focus instead on the light availability for plants and animals on the forest floor & understory. For example, the Wikipedia page has this:
So that (greater light availability) might be another factor encouraging the flora & fauna in your ice-storm forest.
Well, it probably wouldn’t – even less so in a pine plantation. Chris Maser, formerly of the US Bureau of Land Management has said that ‘I know of no nation and no people that have maintained, on a sustainable basis, plantation-managed trees beyond three rotations’ (quoted in Jensen’s Strangely Like War, p.52). But coppiced or pollarded broadleaf woodland survives regular harvesting on a much longer timescale, perhaps indefinitely. Allaby’s point, I think, is that there has been time & space for wildlife to adapt to this management regime – indeed, to become dependent on its continuation – even if the exporting of materials leaves them with precious little to work with on the level of basic fertility. I’m still not saying that I like it, but…
You should know by now that politically incorrect, ‘unscientific’ observations are more than welcome on this site
It doesn’t surprise me at all to hear that the ecology’s spontaneous attempts to heal itself do better than the hubristic tinkerings of people who are totally alienated from the daily realities of that world.
cheers,
Ian
July 14, 2012 at 11:46 pm |
hi Ian – well now, it’s not that you suck, exactly. But it’s always nice when you reappear. I just assume that you have a life outside
Anyhoo, no, the forests I’m talking about are not pine plantations, these are hardwood/softwood mixed forest. They were virgin til about 150 yrs ago, when it was discovered the old growth made great masts for the British Navy’s ships. Since then they’ve been logged over about every 50 years, for various purposes. Now that the pulp industry is dead it’s mainly firewood – everyone here has a wood burning stove. So yes, your bit above on coppicing applies, in a way. It’s not that coppicing happens, so much as selective logging, so we get the meadows, etc.
Here and there, of course, we have those dreadful pine deserts but not near as many as in other, more developed areas. Our ‘Pontiac’, the federal riding, is about the size of Belgium, very rugged and mostly ignored by the rest of the country, a real blessing for nature.
However, when the ‘reveneurs’ (gov’t) get involved and rules of forestry management are followed, that leads to heavier logging and then reforestation – tinkering.
I’ll try to get some decent pics of forest up on my blog so you can have a look – it’s really gorgeous and wild, you’d love it. There’s a few there already but I have more waiting.
July 14, 2012 at 11:51 pm |
Oh, and Paul and I are heading for a place called Manitoulin Island for a few days, where there are amazing examples of forest management by the natives, still thriving. It’s going to be great to see, there’s one spot that’s mostly meadow, but dotted with old oaks and juniper. Interesting combination, isn’t it? Hope we can find it again, it’s a big island…
August 5, 2012 at 10:13 pm |
Hey Christine,
Not exactly a ‘life’ per se. More like a ‘job’
Only 3-4 days per week at the moment but it’s a big energy drain that makes it difficult to keep up with the multiple activities (including blogging) I got on with before. Garden maintenance + a 40-45min cycle commute in case you were interested to know…
Anyway, a couple more topical links:
Another example of too much fertility I should’ve mentioned above, ‘Fertilization’ in waterways and out to sea through nitrate runoff from farms:
But this doesn’t mean actively working to keep the oceans nutrient-poor. Here’s an example of the wonderfully intricate interspecies relationships that can evolve through the movement of nutrients from one zone to another:
Finally, you may have to junk some of the above comments on coppicing. Searching around Mark Fisher’s site, ‘Self-Willed Land‘ (an excellent source for debunking the claims of those in what he terms the ‘conservation industry’) I came across this article which references a piece from 1995 published by two Oxford-based ecologists, Clive Hambler and Martin Speight: ‘Biodiversity Conservation in Britain: Science Replacing Tradition‘. I found it an incredibly useful and important read, in spite of strong disagreements with several assertions. More on that later when I have the time, but basically my interest in foraging has biased my attention towards plantlife, especially that which provides a direct practical use for human beings. So the effect of coppicing in making more sunlight available for herbs and shrubs under the forest canopy sounds great to me. But it turns out that in woodland the real action lies at the smaller end of the scale:
If your focus is on biodiversity and preventing species loss, then traditional management doesn’t seem to be the way to go, as most of the threatened species are the specialists that thrive in the relatively undisturbed interiors of climax woodland – the ‘endpoint’ ecology for most of Northern Europe.
Hmm, some interesting implications in there for permaculture and forest gardening, with their stress on maximising edge and availability of sunlight. Perhaps the thing to take away from this is the importance of ‘neglect’ and not having a ‘working countryside’ straining everywhere to fulfill human desires. Maybe coppicing has a role on woodland edges as somewhere to provide essential building or tool-making materials. It definitely shouldn’t dominate all areas of woodland though, whose management we should leave to those who need freedom from our heaviest disturbances in order to survive.
August 6, 2012 at 2:50 am |
Hi Ian – ah, my husband was doing the same sort of work when we first met. Exhausting. And not terribly rewarding all the time, either. My sympathies.
Anyway, many thanks for all the (as usual) v. interesting reading. I enjoy Mark Fisher’s site. Maybe one day “conservation” will begin with the smallest micro-organisms and work up.
I’m reminded of the importance of salmon to forests in British Columbia. As the Grizzly bears catch the salmon and leave partial carcasses to rot, these enrich the soil – it turns out low salmon runs are the cause of degradation of otherwise protected old growth forests. Try telling that to the foreign trawlers in international waters off the coast, though, and see if they care.
I have long had my doubts about certain aspects of permaculture. As far as a gardening method on the smallish scale, I love it. But when it comes to managing larger landscapes the way they do, well, it always seems very human-centered. Sepp Holzer is amazing yet I can see why he makes the locals squirm, too.
A piece of land has just come up for sale near us, dirt cheap, too, at $175,000 – it’s 156 acres. One side of a small mountain and a bit of marshy lake at the bottom fed by a lovely clean stream. Because the terrain is too difficult to log, it is mostly pristine. There’s an old farmhouse that would be very easy to take back off grid and maybe 5 acres of arable land.
I wish I could buy it and just. leave. it. be. One could learn so much.
August 12, 2012 at 3:14 pm |
No, not hugely rewarding for the moment. Probably not a good idea for someone who likes wild plants to get a job where he spends a large amount of time killing them because ‘they’re weeds’. On the other hand it’s good for overall fitness levels and working in the fresh air etc. When not choking on strimmer fumes, that is…
Yeah, I’d heard some things about the salmon connection. Pretty amazing long distance relationships there!
Not familiar with Sepp Holzer. What’s he up to?
Hope that land goes to a sane person. A bit outside my price range at the moment!
best,
I
January 6, 2013 at 1:25 am |
[...] site. Basically, that Hambler & Speight article I linked to under the ‘recent’ post about soil fertility had me questioning and ultimately rejecting a lot of the standard lines you [...]
April 10, 2013 at 3:48 am |
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April 27, 2013 at 5:12 pm |
Pretty good NatGeo article on Nitrogen, over-fertilisation and runaway agricultural output: ‘The Curse of Fertilizer‘ touching on many of the above points and filling out some detail (h/t Vanessa). I thought this was particularly well put:
Although the author made the usual howler of putting the cart of human population before the horse of agricultural surplus:
Well, okay, maybe the old peasant traditions didn’t play so much of a role in it but those additional 300 million people came into the world as a direct result of the higher yields made possible by nitrogen fertilisers and the new plant varieties that were bred specifically to take advantage of them. If anything it was the human population which ‘struggled to keep up’ with the massive expansion of food availability and an artificially increased carrying capacity of the land. More food = more people.