ceog Hatfield

Emerson White wrote:
1) The flooding problem is not that too much water goes down the river, but rather that too much goes down at one time. What would come down in a matter of weeks is now spaced out over a matter of months. Now if you like the flooding you are SOL but if not then beavers are useful.

Do you mean it used to be months and is now weeks? Or that the beavers have returned to your neck of the woods and things have improved?

I was wondering about how much effect beavers have on general flood prevention. Beavers build dams to maximize area of water, not volume of water. If they detect a leak (by sound or water flow) they go and plug the leak.

Assuming that, the height of their dams are tailored to the normal rate of water flow. They aren't going to pro-actively prepare for the next deluge (I presume). If flow rates increase temporarily due to a storm, it just escapes either over or around the dam before they have time to add another inch to the height of the dam.

Once the dam is full, the flow out=flow in - evaporation. So I'm not sure that would be very noticeable. (and as you point out, the evaporation will fall back to earth soon anyway)

It would have an effect during a dry season, where any increased flow would top-up the pond before continuing down stream, but that would just extend the dry period down stream. I'm guessing it would have less of an effect on major seasonal floods.

Firstly - as often here, I'm not sure exactly what my question is. It is something related to the risks, benefits, duties and responsibilities of introducing species.

The simple way of living is adhere to simplistic rules. Don't plant anything that hasn't been declared native, and pull up anything that has been declared introduced. However I don't want to do that. For a start I'd have to repatriate myself back to Europe, and presumably on to the Great Rift Valley, with a measurable percentage stopping off in Mongolia. Secondly I want to eat things that are not native to Southern Ontario.

So, given I've decided to break the simple rules. I need a new set of rules to follow.

A specific case study - at the moment I'm interested in 2 native North American species considered non-native in Southern Ontario - Northern Catalpa and Black Locust. From the official MNR documentation (Ontario Ministery for Natural Resources)... For the Northern Catalpa it asserts

"Not recommended because: Native species adapted to our local environment are always preferred to introduced species which often contribute little to our ecology and the web of life that sustains us."

For the Black Locust is asserts

"Not recommended because: Native species adapted to our local environment are always preferred to introduced species which often contribute little to our ecology and the web of life that sustains us."

This is just the simplistic rule I've decided to ignore, so the information is of little use to me. Also, from further reading, of the two, the Black Locust (fast growing, nitrogen fixer, rot resistant, high energy fuel) is criticised as very invasive, whereas Catalpa (pretty, but not much use) is mostly harmless. This further encourages me to ignore the simple rule which doesn't distinguish between them.

On the one hand 'local plants are adapted to local conditions' on the other hand 'invasive plants out compete them'. Surely the 'locally adapted plants' would have evolved a better strategy... so when that once in 100 year event comes along, bye-bye invaders, so why worry?

OR... are the local plants just not competitive enough, due to having had it too easy since the end of the last ice age without enough true competition?

OR.. the local adaptations are from 300 years ago when winters were harsher and the current set of mature trees sprouted. We should be sourcing trees from further south?

Given that human populations are living here in greater numbers than ever before, is it the duty of the most environmentally influential (vertebrate) species to dissuade monocultures by introducing new species of trees and actively managing woodlands, finding replacements for native plants that are affected by disease - for example Elm, Ash, Chestnut? Or just wait for the next ice age and see what survivors make it back up north next time?

Should we not move forward from where we are now, to a sustainable future, as opposed to attempt to return, guilt ridden, to a past perceived golden age of natural purity?

Erica Wisner wrote:
I don't think I've seen beaver-felled trees much over 1 foot diameter.  Usually, they're more in the 1" to 5" diameter range.  To make use of them for dams, the beaver generally has to be able to drag them.  Most of the trees they chew are small branches for food.  They can clear out brush quite a lot, tho.

I have a number 10" diameter trees brought down by beavers. They are very helpful. They fell the trees and strip the branches, leaving nice logs ready for sawing for firewood. They just don’t do it on demand - time or location.

That said, I was also referring to trees that get drowned by rising water levels, not just those directly felled by the beavers. But again, I don't know how long there is between beaver cycles in a given area, and how big trees might get between cycles. So maybe beavers seldom kill ancient trees, but I can’t find facts, I just have ideas, hence this discussion

Erica Wisner wrote:I've seen a lot of 600+ year old stumps that got chewed by chainsaw or 2-man saw, though.  Don't be pointing the finger at the beaver for our own mess.

Trying to read between the numbers, it seemed like somebody was trying to evaluate some kind of beavers vs. trees benefit analysis.

I am not pointing fingers at beavers or humans. I am merely trying to understand how it all fits together. I know it's complicated. There's no "beavers vs. trees benefit analysis" going on. I would not base any actions on a calculation about how much water the land would retain - even if I believed I could know that. I just want to know out of a desire to understand, not just believe.

Besides, beavers are far more than just how much water they hold back. They create variety in areas that would otherwise just be perpetual forest, and presumably ultimately a monoculture of White Pine (in this area), until the next big fire came along and the process stared over again.

Erica Wisner wrote:That equation seems to rest on a false assumption.  No point using logic if you don't have an axiom to stand it on. 
It's very difficult to apply simple numbers accurately to ecological interactions; they are notoriously complex, and hidden, compensating factors keep emerging layer after layer.  Simple relationships are the exception rather than the rule.

I agree that logic is easy, facts are hard. I state my assumptions, so they can be refuted. I would suggest it is even more dangerous to base logic on axioms! Apply logic to assumptions / facts that can be tested, as opposed to someone's declarations of axioms.

On the other hand, if one just accepts that things are too complex to understand, then one risks becoming a believer, which brings different dangers.

Erica Wisner wrote:It looks to me like both beavers and big trees have declined with industrial expansion, and other landscape-eroding and groundwater-reducing factors have increased with that same expansion.  You can chart the decline of life-supporting environmental quality factors on a very macro scale.  Some is due to geologic climate shifts, or introduced species, but much more to industrial effects.

Nothing to do with industrial expansion. Just human expansion. Long before industrialisation, human society was over using resources. Industrial expansion has just allowed the numbers of humans to rapidly increase -- so far.

Erica Wisner wrote:
What interested me in this thread was the perspective: a 'minor' creature like a butterfly or beaver, can have major effects that are visible in hindsight.

I would suggest that they are not visible, but perceived. I question whether the removal of beavers was the main 'industrial' problem, or simply the logging. I suspect that logging was the issue. After all everyone knows that killing a family of beavers and destroying their dam just makes an ideal site for a new beaver to move in. But ultimately I too have no facts, just thoughts.

Would logging (of white pine) not just increase the number of suitable sites for beavers?

Erica Wisner wrote:
With current rates of extinctions, when the crap hits the fan we probably won't even know the name of the lost creature that tipped the balance.

We are lucky in the case of the beaver: its numbers are recovering.

Nothing to do with luck. It has to do with responsible human discourse and debate... and the advent of cash cheap fossil fuel based materials.

Erica Wisner wrote:And in the case of industrial expansion: it is fueled by a resource glut, and unlikely to last forever.

I agree - at which point, the trees will go as the choice of individuals will be suffer now or later, or indeed suffer now and allow your neighbour to not suffer now. And then eventually later arrives.... but now I seem to be going OT  ops:

An interesting link if you want to convert your car to wood... They get consumption of 1.2 litres of wood per kilometre.

http://www.vedbil.se/veddrifte.shtml

I wasn't aware the Hudson Bay Company went west too. Thanks.

I think it is important to be aware of the facts as much as possible. Science is important. For centuries malaria was presumed to be caused by "bad air" - hence the name: it seemed obvious. You lived where the air was bad and you were more likely to get sick.

I was just trying to understand the relative effects on water flow of beavers building dams and in the process destroying trees, verses trees on their own. Nothing to do with 'good' vs 'bad'. Everything is good for some species, in some timescale. Floods and fires too are good, though often not for humans.

Humans generally encourage what they want for themselves in their short lifetimes. Ancient trees dying are bad for individual humans, as we cannot wait another 600 years for them to re-grow. This is why we constantly try to avert natural fires, and worry about beaver damage.

When I searched for information on beavers, I could find very little. Most sites are about how to get rid of them. Most of my understanding comes from this very informative (and I hope trustworthy) site http://www.sacredbalance.com/web/pond/

As an aside - The area I'm in requires local environmental agency permits for work within 30m / 100ft of wetland... but that doesn't include beavers - you can get rid of beavers and remove their dams, it doesn't seem to count as wetland. Currently I'm happy with my dam and pond. Camping to the sound of spring peepers is up there on my list of fantastic moments.

However if I thought I would lose my big trees, I would likely abandon my laissez faire approach.

PS I also realised that my (troubled) maths doesn't take into account that it isn't 1 beaver per pond, or that those 5,000,000 pelts were over a 200 year period.

There are many beavers in a pond, and many generations over 200 years, so that would significantly reduces the amount of water per beaver 

Thanks everyone - I just now have to wait until spring before I can do anything with these options. 

I must say that everyone I've met in the area has increased my enthusiasm for leaving the city, so thanks for the invite, I definitely plan on meeting more people in the area.

Mukwah,

Firstly - I'm afraid I have no idea if your plan would work. That said, it seems to me to be quite a lot of work. How big is the area?

The western part of my property is pretty much impenetrable at the moment. Thickets, water, grass and small trees. To resolve this problem we renamed it "The Wilderness", and decided to let *it* decide what it wanted to be. It looks like it is planning on reverting to forest, or maybe bog... time will tell.

We have plenty of ideas for the eastern portion of the property to keep us happy.

When you say you want to 'enjoy from above' what do you enjoy? Green? Flowers? Shapes? Smells? Wildlife? Food?

You could just leave it alone and rename it "The Alpine Meadow" and if it turns into a woodland, you can rename it again.

Humblebee: I agree that leaving plants behind is difficult. I used to have many blackcurrent bushes on an allotment 10 years ago. I would make the most delicious jam I've eaten, on the down side I've hardly had blackcurrent jam since. My expectations are too high

Thanks Travis for the links. Some good options there.

We're a bit east of you. Between Madoc and Kaladar not far off Highway 7.

thanks for everyone's comments - they have all been noted.

humblebee: What varieties of nuts and plums did you grow? Or perhaps more importantly - what were the most successful?

rockguy wrote:ceog~ Please go over your numbers again before you apply them to any practical application. Your "gallons per ac/ft" figure is less than the square ft per ac.

Thanks rockguy -  you're completely correct. I should have put ALL my calculations, and maybe I would have realised I mistook a cubic foot for a pint ops:

That makes 1 cu foot = 6.2 imperial gallons not 1/8 of a gallon. So I'm out by a factor of 50... so...

1 acre foot = 43 560 cubic feet. = 271 328 gallons. (500 trees would take 10 days to absorb)

8 acre feet of water would take 4000 trees 10 days to absorb *all* the water held back in the pond.

based on this chart of trees per acre http://www.hybridpoplars.com/space.htm 4000 mature trees is not feasible, so to make the numbers work, I'd have to have increase the time to absorb.

So for holding back water, a beaver pond holds back more water, but once full, it would not be able to hold back any additional water, whereas trees would continually reduce water.