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How do we measure health in an ecosystem?  RSS feed

 
Gilbert Fritz
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Location: Denver, CO
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How do we measure health in an ecosystem, either a wild one or a created, permaculture one? So much of our work, and so many of our debates, are based on creating healthy systems, or helping wild systems to become healthy. But what is health?

For instance, molybdenum deficient soils in Australia hosted a unique plant community. By broadcasting a few ounces of molybdenum per acre, this community was wiped out and it became useful farmland. (But was it wiped out by the molybdenum or by the farmers? ) So soil "health" is not a good indicator.

Similarly, adding new species adds to biodiversity. But it may wipe out unique species. So biodiversity of any given area becomes meaningless. Then again, this only says something about a given action, not a given system. It is not impossible that even with the loss of a unique species, that lowers the health of the world in general, the health of a given ecosystem could go up, though this is not the usual case. Also, a horribly designed garden may be very diverse, but require constant inputs to keep it that way and provide little cover for wildlife. So biodiversity is not useful as a stand alone indicator.

Looking at what existed before human habitation is relatively useless for determining the health of a permaculture system; I have yet to see a permaculture system composed of only native species. If I wanted to only use native species here in Denver, my plot would be rather sparse. (A related point is that just because a plant is native to a state, does NOT mean it is native to a yard; thousands of aspen are planted in Denver, but they are not native here, but only to higher elevations. )

Biomass is not a great indicator; I'm sure a kudzu thicket has more biomass then a native meadow.

Stability may be a good indicator, but it may not be. Some ecosystems/ permaculture plots may be stable but over mature. Evergreen plots may be stable, but they can be ecological deserts.

What are good indicators, and how should we weight them?
 
Tyler Ludens
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I'm not trained as an ecologist, so my opinions are only those of an interested layperson. From what I have learned, a healthy ecosystem is diverse and relatively stable - that is, there are many species of plants and animals and extinctions are low. Predator-prey relationships are somewhat balanced over time. Keystone species are in place.

I'll try to find some articles by actual ecologists discussing what makes a healthy ecosystem and how do we measure it. I think we should look to the people who actually study ecosystems, instead of relying on our own possibly uninformed opinions. We wouldn't think our uninformed opinions about nuclear physics are accurate if we aren't nuclear physicists, so I believe we shouldn't think our uninformed opinions about ecology are accurate if we aren't ecologists.

Obviously we can choose to inform our opinions by study.

 
Tyler Ludens
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This article give criteria for measuring ecosystem health: " We propose that a healthy ecosystem is one that is sustainable – that is, it has the ability to maintain its structure (organization) and function (vigor) over time in the face of external stress (resilience)." http://link.springer.com/article/10.1023/A%3A1009930313242

Assessing ecosystem health, with links to more information: https://learning.conservation.org/biosurvey/projects/Pages/AssessingEcosystemHealth.aspx

Here's an article which discusses several criteria for ecosystem health: http://onlinelibrary.wiley.com/store/10.1890/EHS14-0013.1/asset/ehs21400131.pdf;jsessionid=EF0C5278002EBEA2672BCC57FB7BF411.f02t04?v=1&t=iocui3lq&s=e52bb34170ded4e826f2df2706ac0f8d24af312c

This article discusses the development of criteria to measure ecosystem health: http://www.ecologyandsociety.org/vol12/iss2/art6/

Ecosystem health indicators for Scotland: http://www.snh.gov.uk/docs/A1308427.pdf

There are tons of articles out there, and scholarly papers some of which might only be available by subscription.
 
Gilbert Fritz
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Hello Tyler,

I couldn't access some of those, but thanks for looking around for stuff. From the abstracts, it looks like most of them would not be applicable to our hybrid/ novel permaculture setups; we don't have a good grasp on "indicator" species for these.

Also, about the stability; aren't some ecosystems inherently unstable? For instance, chaparral, which needs burning to keep it from becoming something else, or meadow, which also needs burning. So then what about a garden "ecosystem" which needs weeding?

And aren't some ecosystems, especially evergreen forests in boreal areas, low diversity?
 
Gilbert Fritz
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Something along these lines, from an EPA blog; https://blog.epa.gov/blog/2008/04/what-is-a-healthy-ecosystem/

Ecosystem health is hard to measure. And while Tyler's links point to some indicators of health for "natural" ecosystems, I can't find any metrics to measure the impact of what we do on our land, without "hybrid" ecosystems.

Of course, is there such a thing as an ecosystem? Or just a collection of plants and animals! I think there is, but defining it, and defining ecosystem health, seems like nailing a custard pie to the wall!
 
Tyler Ludens
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Gilbert Fritz wrote:
Of course, is there such a thing as an ecosystem? Or just a collection of plants and animals! I think there is, but defining it, and defining ecosystem health, seems like nailing a custard pie to the wall!


It probably helps to actually study and understand the science of ecology, which might take awhile, years even!

 
Gilbert Fritz
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Yes, but in most other areas, one can get an answer from the experts, without doing years of study. Instead, over my last few days of research, I've got all sorts of answers, most of them "it depends!" And that is what permaculture folks tend to say too, of course.

Basically, I can't find anything written that would be relevant to determining the health of a permaculture ecosystem.
 
Tyler Ludens
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Gilbert Fritz wrote:
Basically, I can't find anything written that would be relevant to determining the health of a permaculture ecosystem.


Perhaps this is an area which requires more scientific study. Permaculture is a relatively new discipline, so there's probably not a lot of scientific study been done on it. This is something Neil points out a lot. So perhaps the answer would be to learn a great deal about ecology, and then apply that knowledge to a study of permaculture systems.

 
Neil Layton
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Tyler Ludens wrote:
Gilbert Fritz wrote:
Basically, I can't find anything written that would be relevant to determining the health of a permaculture ecosystem.


Perhaps this is an area which requires more scientific study. Permaculture is a relatively new discipline, so there's probably not a lot of scientific study been done on it. This is something Neil points out a lot. So perhaps the answer would be to learn a great deal about ecology, and then apply that knowledge to a study of permaculture systems.



It's not so much that permaculture is a new discipline. Agroecology as a field of study has been around for less time but has a much bigger body of published work. There are historical reasons why permaculture has lacked supporting empirical data, going back to Mollison.

To answer Gilbert's question I'd first need to spend an hour explaining the problems inherent in the question. This summarises the problem: https://en.wikipedia.org/wiki/Ecosystem_health That's not Gilbert's fault by any means, but understanding the implications of the question is not trivial.

Then I'd need to equivocate about the answer. There are matters where I'm happy to come down on one side or another, on the basis of evidence, and it can be very difficult to get me to budge without good contrary evidence. This generally means I've done a lot of reading on the subject. I've done a certain amount of reading on this subject: enough to know that the answer is "it depends on a lot of factors, including a value system".

I'd need to ask "which ecosystem, under what conditions, using what clearly defined set of values?" I could give a set of goal statements, which would depend on what zone we were talking about, and I could define a set of values, but that would be a whole other ulcer factory thread. There are proxies you can use to measure diversity (beetles being an obvious one, but that takes specialist skills). I'd give a much higher priority to some goals (such as biodiversity) than others (such as human occupancy, never mind utility), but that in itself would be controversial, and have a whole set of other questions about neighbouring ecosystems (has anything jumped the fence; is anything likely to; what are the plausible consequences).

This is turning into the essay I didn't want to write. The implications of a systematic selective breeding programme on evolutionary processes in the ecosystem is an extended post in its own right.

In terms of the broader question, I'm drafting a long post about science for permaculture. That is unlikely to be finished today. It's nearly 3,500 words already, and will probably need to be split into multiple posts.

I have reviewed two books which may be of practical use:
http://www.permies.com/t/55688/books/Studying-Invertebrates-Philip-Wheater-Penny
http://www.permies.com/t/56250/books/Field-Laboratory-Investigations-Agroecology-Stephen

I have two more in the pile from the same authors, one a companion to studying agroecology, the other a text on ecological surveying.

Please do not hold your breath: I also have two thirds of Toensmeier's Carbon Farming Solution to get through and comment hopefully reasonably intelligently on. There is the rest of the pile, and the descriptive system for patches in such ecosystems (which might help this measurement question) to fix, plus a load of stuff going on in my own life getting in the way of it all.
 
Gilbert Fritz
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Yes, I read that wikipedia article. I guess E. O. Wilson was right about how little we really know; should humble us all.

On the other hand, it is easy to get analysis paralysis in permaculture. Without being able to define it, I think anyone would agree that my food forest will be "healthier" then the lawn it replaced, however we define health; stability, diversity, resilience, biomass, water retention, filled niches, complete utilization of resources, etc. etc., all different ways I've seen people measure ecosystem health.

Your remark about breeding is an important one; I'm now reading the book Tending the Wild, which posits that a few thousand years of tending by Native Americans left many native plants dependant on their activities. And their tending was so much more complex then just "set some fires." So in other words, they would now be key to ecosystem health, whereas they wouldn't have been 8000 ago.
 
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