jean_thie
Cartographer
Reged: 12/06/06
Posts: 96
Loc: Ottawa, Canada
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This shows a typical example how beavers manage water in wetlands in Northern Canada when they are relatively undisturbed. The image below gives a simple interpretation of the area. This area is part of the northern edge of the Boreal zone. Pieces of precambrian bedrock are visible as "islands" in a large wetland area. Most of the watermovement is in the form of "ground water" flows in the wetlands, and the beavers had to build extensive dams to contain the flow.
Beavers are typically boreal and temperate species surrounded by trees which provide a good food supply. The Northern Limit of the Beavers is interesting since beavers seem to follow climate warming trends (not just the last decades, but and are migrating north since the little ice age, the last period of climate cooling a few hundred years ago). With the acceleration in warming, the rate of migration into the subartcic may accellerate along the rivers and streams where they live of willow and alder.
Apparently Moose and Red Fox are also moving into the subarctic, but their "foot print" is not visible on a satellite image. Google Earth with its incredible ability to scale into high resolution detail makes beaver activity and possibly its migration north "mappable"
I am working on a series of transects through Canada's north to establish a sort of baseline on the GE visible status of beaver . Results will be added to this thread on a regular basis. By the way, the typical beaver example above is at the green place mark of the image below which shows a series place marks for site I have looked at
http://www.geostrategis.com
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Jean Thie
Executive Director, Canadian Institute of Geomatics
www.geostrategis.com
Google Earth - An Exceptional Ecosystem Science Tool!
Monitor Permafrost Melting with Google Earth
Fire Ecosystem Interpretations with Google Earth
Map Glacial lake Agassiz!
Find the longest beaver dam in the World with Google Earth!
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mspelto
Tourist
Reged: 12/11/06
Posts: 203
Loc: Massachusetts
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Here is an example from New England to compare. How long to they occupy the sites actively in your area?
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jean_thie
Cartographer
Reged: 12/06/06
Posts: 96
Loc: Ottawa, Canada
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This area in the remote north is, I presume, almost managed by the beavers in some sort of sustainble cycle. Food supply is relatively poor. and as your examples suggest they move along the stream.
I came along this example when I was using Google Earth to map the southern limit of sporadic permafrost ( I believe you do glacier studies if I am not mistaken?)
I have added a bit of an interpretation to the original post.
Also I lived with beavers for at least for 20 years on the Carp Ridge near Ottawa. This area is almost exclusively managed by beavers. I had to put chicken wire around all the trees I wanted to protect. Like we have with farming, they seem to have a kind of rotational system. When the food supply is exhausted, they move on to the next best area, but will be back again when new growt has re-established itself.
In the area A beavers have been active all the time I lived there, maintaining a dam, but not always living there. In area B the started to build the dam around 1992. Before that time they occupied the area C , just downstream the present dam, for at leat 5 years.
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Jean Thie
Executive Director, Canadian Institute of Geomatics
www.geostrategis.com
Google Earth - An Exceptional Ecosystem Science Tool!
Monitor Permafrost Melting with Google Earth
Fire Ecosystem Interpretations with Google Earth
Map Glacial lake Agassiz!
Find the longest beaver dam in the World with Google Earth!
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jean_thie
Cartographer
Reged: 12/06/06
Posts: 96
Loc: Ottawa, Canada
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Gatineau park is in the National Capital region of Canada (Ottawa, Ontario and Gatineau, Quebec. This folder contains just a few of the many lakes, streams and ponds which are "managed" by beavers in the park.
Gatineau Park has one of the largest beaver population densities in Canada. In 2002-2003 aerial surveys 283 active beaver colonies were estimated on the park territory. This amounts to 7.79 colonies per 10 km2. Various surveys have shown that the beaver polulation varies between 1360 and 1950 beavers based on an average of 5.1 animals per colony.
The abundance of beaver is the result of the richness of its habitat, about 50 lakes and a large number of wetlands. The forest cover provides qulaity food.
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Delta102
Master Guide
Reged: 07/07/05
Posts: 4805
Loc: United States
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Nice use of GE 
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jean_thie
Cartographer
Reged: 12/06/06
Posts: 96
Loc: Ottawa, Canada
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Hi Joe, That is a great picture, a text book example in a beatiful setting.
I have added a cross section of a beaver pond taken from a good factsheet on beavers in Hinterland Who's Who 
Also the distribution map may be helpful when looking for beavers with GE.
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Jean Thie
Executive Director, Canadian Institute of Geomatics
www.geostrategis.com
Google Earth - An Exceptional Ecosystem Science Tool!
Monitor Permafrost Melting with Google Earth
Fire Ecosystem Interpretations with Google Earth
Map Glacial lake Agassiz!
Find the longest beaver dam in the World with Google Earth!
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heamit
Master Cartographer
Reged: 10/26/06
Posts: 2333
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Quote:
Also the distribution map may be helpful when looking for beavers with GE.
Well that narrows it down a bit! 
Just kidding! This is a fascinating thread - thanks! 
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Delta102
Master Guide
Reged: 07/07/05
Posts: 4805
Loc: United States
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I have a Place in Montana and I've seen them at work.......... Really quite amazing what they can do
Beavers in Montana
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jean_thie
Cartographer
Reged: 12/06/06
Posts: 96
Loc: Ottawa, Canada
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Thanks Heamit
Quote:
Well that narrows it down a bit!
I appreciate the comment. You are right of course and your comment made me smile.
After that I started my defensive rationalization process: Only with GE can you quickly scan the whole beaver range. Until GE came along totally impossible for the amateur ecologist. And it is of course the Castor Canadensis: just one small example of Canada's heritage in the US
So my next explorations will be focusing on the northern limit of the range, but I will also try my luck in the southern edge, or perhaps somebody will contribute some great sites there!
Thanks
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Jean Thie
Executive Director, Canadian Institute of Geomatics
www.geostrategis.com
Google Earth - An Exceptional Ecosystem Science Tool!
Monitor Permafrost Melting with Google Earth
Fire Ecosystem Interpretations with Google Earth
Map Glacial lake Agassiz!
Find the longest beaver dam in the World with Google Earth!
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jean_thie
Cartographer
Reged: 12/06/06
Posts: 96
Loc: Ottawa, Canada
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Well if this is the view from you place in Montana- not bad. It looks like a more nutrient rich environment compared with your first picture.
Living with beavers is fun, and fascinating, but it can have its challenges. Particularly during spring snowmelt and run off: trying to keep my culvert under the road open was a daily chore. I would clean it up. They would plug it up. Every tree I wanted to keep, I had to protect with chicken wire. OK for a few trees , but for a couple of acres of trees- a chore
Thanks
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Jean Thie
Executive Director, Canadian Institute of Geomatics
www.geostrategis.com
Google Earth - An Exceptional Ecosystem Science Tool!
Monitor Permafrost Melting with Google Earth
Fire Ecosystem Interpretations with Google Earth
Map Glacial lake Agassiz!
Find the longest beaver dam in the World with Google Earth!
|
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