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how to measure the healthiness of a forest

 
Ronaldo Montoya
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Hi, i was wondering how can i measure the healthiness of a forest or an ecosystem?

Are there sensors that allows to measure this?
which data from a forest should i get that reflect the healthiness of the forest?



any idea?

 
Dave Burton
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Location: Greater Houston, TX US Hardy:9a Annual Precipitation: 44.78" Wind:13.23mph Temperature:42.5-95F
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What kind of forest are we discussing?

The health indicators vary between climate zones. Also, it depends on what you mean by "health of an ecosystem. Do you mean the resilience of the ecosystem? Resilience is an ecosystem's ability to return to normal after a catastrophic event (i.e. a fire occurs in the savanna and the grasses return quickly). Do you mean the persistence of an ecosystem? Persistence (resistance) is an ecosystem's ability to prevent catastrophic events and remain unchanged when things do happen (i.e. the high biodiversity of the rainforest and fast nutrient cycling prevents invasive species from taking control because all niches are taken and held onto very tightly).

At the moment, the best indicator to use would be biodiversity and relationship strength. High biodiversity and weak interactions are important for a healthy ecosystem. Biodiversity creates a complex food web of connections between organisms which leads to persistence. Depending on the composition of species, the ecosystem may or may not have resilience. Weak interactions are important because when one food source becomes unavailable, the predator can switch over to eating a new species relatively quickly. For example, imagine one cow prefers to eat crab grass and occasionally eats bermuda grass. The crab grass goes extinct, but the cow knows the bermuda grass tastes OK. So, the cow can now transition smoothly over to eating bermuda grass.
 
Michael Qulek
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From a forestry aspect, individual tree health, and subsequently the health of the whole can be determined by what's called "site index". At least for the coniferous trees of the continental US, site index is defined as the numerical value equal to the height of individual trees at are of a specific age. Within a species, height, more an any other individual characteristic is a good indicator of health. Let's say a stand of trees is known to be 40 years in age. Let's also say that those 40 year old trees are 50 feet tall. Comparing other trees of the same age and species, trees that were 60 feet tall would be more vigorous, while trees only 40 feet tall less.

Typically, you'll see a set of curves for a particular species over time. The standard time may be 100 years. If the trees are 120 feet tall at one hundred years, those trees have a site index of "120". If only 80 feet tall, the site index would be "80". Going back to your graphs, you can plot your tree's height, against it's age and come up with a value for what height the tree is likely to reach when it's finally one hundred. Here's a web page that explains it in much more detail. http://www.cof.orst.edu/cof/fr/research/organon/pubs/FRL_RB59.pdf
 
Dave Lodge
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Location: New England
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For me the healthiness of the forest would be in bio-diversity and diverse wildlife capacity. Mushrooms can be indicators of healthy soil, and also unhealthy plants. All the layers intact, herbecous, shrubs, understory, canopy. And possibly second succession forest coming in. In the northeast coastal forest (USA), there are understory trees that will fill in gaps in the canopy (Sugar Maple, American Beech) caused by wind throw usually or ice damage.



01-canopy_structure_600.jpg
[Thumbnail for 01-canopy_structure_600.jpg]
 
Michael Qulek
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Dave Lodge wrote:For me the healthiness of the forest would be in bio-diversity and diverse wildlife capacity.
Ya know, that all sounds so wonderful, but one of the problems I think with the permaculture community is lack of objective documentation of anything that has a real effect. Not saying that it isn't important, not saying that it isn't the single most important factor, but the original poster is talking about "measuring" health. Something tangleable that can be written down on a piece of paper.

That I think is the single biggest hangup with permaculture enthusiasts is the inabillity to quantifiy anything. And it's one of the things that turns permaculture into a religion, instead of a science.

Dave, have you actually documented in any way your particular little forest, or is it just some vague feeling the forest gives you? Do you actually count the number of different species, or the population density of an individual plant or animal? I used to work for the US Forest Service, and this was something I used to do on a daily basis. I can tell you it takes a lot longer, and is much more labor intensive than just measuring the height of a tree.

Getting back to Ronaldo's orignal question, I think another easily quantifiable factor related to tree health and vigor is a term called "crown ratio". It's the relationship between the total length of the tree and the length of the leaf/needle bearing branches. Let's say you have two trees that are 60 feet tall. One tree has a crown (leafy area) covering about 30 feet. The second tree has leafy area covering 50 feet. Tree #1 would have a crown ratio of 30/60=50%. Tree #2 has a crown ratio of 50/60=83%. The tree with the higher crown ratio is in general more healthy than the one with the lower ratio. Again, this is another example of a very easy, at a glance, method for quantifiying health.

You can take this a step further, and quantify the overall crown coverage of an entire area. If you look at the graphic in Dave's post, you can see that the canopies of the trees (the crowns) more or less completely cover the ground. This typically happens when most environmental factors like soil, nutrients, and water are met, and the primary factor the plants are competeting over is light. The overall percentage of total land the crowns cover can also give you an easily quantifiable number to write down, which is easy to get from aierial photos.
 
Dave Lodge
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Location: New England
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I came into permaculture from the conservation side, with trying to add more edibles into environments while achieving conservation goals. One part of permaculture is ecology and being good to the planet, so I think it can be productive to bring both together.

Productivity in a forest in a forest is higher in recovering forests where they are filling gaps in the canopy. Increase light starts to enter the dark forest and a diverse amount of plants fill these gaps. closed canopy is 73% productive, compared to the peak 75% or so open canopy, in studies with understory productivity for herbivores. Selective opening of the canopy will give you better productivity. I have seen other studies too, on some conservation land, but I don't have a link to it. This is due to the edges being created and dispersed over a somewhat larger area than the canopy to increase productivity under other trees.

http://www.mttreefarm.org/Forestry-Tips/graze.pdf



I am currently on about 7000sq ft in an urban area, in a ravine. Tree cover is oak/pines with witch hazel, sugar maple, American chestnut, black birch, black cherry understory. Invasives (wisteria, bittersweet, burning bush, japanese knotweed, Himalayan Blackberry) cover most of the ground with some Path Rush, , Native Blackberry, Black Raspberry, ferns, woodland knotweed, enchanters nightshade.

In my yard it used to have old red oak trees, that were taken out 20 years ago, and some of the logs remain. Regrew with black locust, catalpa, butternut, sugar maple, red maple, black cherry, Japanese maple, tree of heaven trees. Invasives (wisteria, bittersweet, burning bush, Himalayan Blackberry, Boston Ivy), Native Blackberry, black raspberry, goldenrods, white snakeroot, pokeweed, enchanters nightshade, Virginia creeper, yellow wood sorrel, woodland knotweed. Pretty low biodiversity, and a lot of invasives. Now just letting the natives grow and plant more native diversity. Limited places for natives to come in from since its in the middle of the city.


Measuring is hard to do as a healthiness protocol for sure. Different aspects might got into that can be measured and analyzed. These areas can be seen to increase or decrease over time. Simpler things such as harvest amounts, trunk size, canopy coverage, leaf litter amounts, mushroom counts, sapling numbers, tree spacing, grass coverage, and so on.

Probably a good idea for someone to make different lists or checklists or tools people can use to analyzed these different factors on a limited resources or complexity. If you went out one day and saw 100 mushrooms, and last year you saw 110 mushrooms in one day when you counted, you might think it is going down, but the factors of analyzing the numbers would not make it objective information to go off of. So these "concepts" of change are not the reality of change, and these can be made clear with a checklist maybe. The scientific process should be applied more before making big changes.
 
Ronaldo Montoya
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As Michael said, i need to be able to quantify the amount of healthiness of a forest.
This is for an experimental project im working on, i need to be able to send the health value in real time into a software im developing .
Which variable that can be mensurable in a forest can represent the healthiness of it?
Is it possible to automatically measure biodiversity? The idea is to have some kind of sensor in the forest or cam that can automatically measure the amount of healthiness in real time.

Do you think there is a relation between the complexity of the forest and its health? I have seen that in the amazon forest theres a lot of complexity in the patterns of the plants and i think this can be mensurable with a camera or with a 3d scanner or maybe a kinect.


the idea of the project basically is how can we connect a biological process into a digital process in a way that we can have an architecture of a system that helps to take care of the biological process ?

any crazy ideas are welcome.


cheers







 
Shawn Harper
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Location: Portlandia, Oregon
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I guess I am in the "seeing is believing camp." When I walk into a nature park it just feels better than a regular park. It probably doesn't help that most big environmental groups don't quantify so there is few enough numbers around. How do I quantify a spotted owl or a monarch butterfly, I can't fathom it. I guess the best way I could think of to quantify a food forest is to record all food received, animals living there, and resources put into it and somehow turn that into a score.
 
Michael Qulek
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Shawn Harper wrote: How do I quantify a spotted owl or a monarch butterfly, I can't fathom it.
Just because you are incapable of "fathoming" it, that doesn't mean it's "unfathomable". My professional career spans the fields of forestry, biological control, and microbiology, and although I am not inimately knowledgeable about all the literature about Spotted Owls, or Monarch Butterflies, I know that others are, and they do a very good job of turning them into quantifiable data that can be studied and acted upon.

This leads to a much, much more basic question I think, and that is should permaculture be considered a science or a religion? That is, should the concepts of permaculture be a set of unquestionable beliefs based on feelings, or should they be documentalable procedures based on the data of rational quality science. I think in the past, the harshest criticism leveled against permaculturalists has been their inablity to construct a rational framework to emperically document what works and what doesn't. What Ronaldo is trying to do here is think of rational ways to document the effects of permaculture techniques, and I hope my information has been supportive.
 
Dale Hodgins
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Lichens grow on my rocks and trees. I think that's a good indicator.

Species mix amongst trees is important for soils and the nutrient cycle. When a forest burns or blows down in Coastal British Columbia, red alder, our #1 nitrogen producer, usually becomes dominant for 20-60 years. Conifers eventually shade them out and dominate until the next major disturbance which might be hundreds of years down the road. Tree farms where conifers were planted and alder were suppressed, experience acute nitrogen deficit after 60-80 years. This is a recipe for a less productive and less resilient forest. Even aged stands of conifers are prone to burn or blow down. There's not much for furry critters to eat in a coniferous monoculture.
 
Michael Qulek
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Ronaldo Montoya wrote:
This is for an experimental project im working on, i need to be able to send the health value in real time into a software im developing .
Which variable that can be mensurable in a forest can represent the healthiness of it?
Is it possible to automatically measure biodiversity? The idea is to have some kind of sensor in the forest or cam that can automatically measure the amount of healthiness in real time.

You have to be very careful in the interpretation of species diversity. A hallmark of diversity is that maximal species diversity occurs at the equator, and maximal species density occurs towards the poles. I've seen this myself. In a location like northern Idaho, or southern Canada, you are already likely to encounter forested areas where only one single tree species may be found. In equatorial Malaysian rain forest, you aren't likely to come across two trees of the same species on one acre of ground. That means diversity would be a good indicator for longitudinal comparisons, but not latitudinal ones.

A somewhat different measure I think would be the relative population density of the animal predators in a particular ecosystem. This may hold for both terrestrial and aquatic ecosystems. There's always a pyramid of life usual raising in terms of body size. On land it starts out with insects feeding of plants, the insects get fed on by larger insects. Those get fed on by mice, the mice get fed on by smaller predators, and finally up at the top is typically the biggest predator, a wolf, lion, or eagle. Same for the oceans. The planton gets eaten buy little crustaceans, they get eaten by forage fish like mackerel, which in turn get eaten by larger fish like tuna. Finally the tuna get preyed upon by the top of the food chain, sharks. It's the relative population density of the top predator (top of the food chain) that is the indicator. If the top predator's population is stable or increasing, you could think that ecosystem is growing more healthy. If the top predator's population is declining, or going extinct, then that ecosystem's health is declining. Again, you wouldn't want to compare an equatorial estuary with an arctic one, or an equatorial forest predator with a polar one.
 
Jeff LaPorte
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Location: Southern Ohio, Zone 6a
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Heres a couple of videos that might help. One is a 2000 year old food forest in morroco the other is a 300 yr old food forest in Vietnam.


 
Andrew Mateskon
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Here is a project from Greenpeace attempting just such a thing.

http://en.m.wikipedia.org/wiki/Intact_forest_landscapes

http://www.intactforests.org
 
Clarence Hagmeier
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First, you have to decide what you mean by "healthy". If you have meadow full of exotic grasses, grazed by an exotic ruminant and some exotic fowl in a way that makes the
land more fertile, is that a healthy ecosystem? I'd say yes. Is it a tree farm, a second or third growth forest, scheduled to be cut again at some point in the future? Is it old growth,
never been logged? You have to look at the history, to see trends.
The health of the top predator seems like a good, quick rule of thumb.
Another line of questions you could ask is, is every niche filled? (Preferably by native species, if possible.) What niches are threatened, and how important are they to the rest of the
system.

I stress knowing the history. The parable of the cattle, who eat their preferred grass to extinction, and so they simply switch to their second favorite. The first post-extinction generation,
having never tasted that wonderful stuff, think they live in a perfect world. Everywhere they go, there's something to eat.
My point is, we humans are like those cattle. An example from NorCal: We have rivers here that 2 or 3 hundred spawners in a run is a good year. Just a hundred years ago, a
large family might have taken that many home to keep them through the winter. We don't depend on salmon any more. We've found other stuff to eat. And when those run out, we'll
find something a little less palatable, and the next generation will never know the difference.
 
Joey Dodson
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Location: Hunan, China
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Ronaldo, I think you need to define the scope of your project first. Theoretically, how are you defining health? Are you thinking about a specific ecosystem or site or general rules that might be broadly applied? For example, do you think it's possible to measure the health of rain forest and desert ecosystems in the same way? Are you including man-designed food forests or are you intending to focus on totally natural ecosystems? Practically speaking, you'd need to consider the difference between what you want to measure and what you can measure. That is, will you have to design new sensors to complete this project? Or are you planning to design the project around existing sensors? For example, can you automate measuring the levels of humus in the soil? Depending on the answers to these questions, you may have vastly different research goals and vastly different implementations for your system.

That being said, Bernie Krause has a great talk about using sound to measure the health of an ecosystem in an aggregate way.
http://www.ted.com/talks/bernie_krause_the_voice_of_the_natural_world

There is also a project using audio feeds from re-purposed smart phones to detect illegal logging in rain forests as it is happening and alert local authorities.
 
Sean Banks
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look at an old growth forest......that is a place that has reached peak "health".......mycorrhizal fungi are fully established and there are distinct layers....these systems can last thousands of years if left undisturbed.
 
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