Program Item Details
TITLE: Dr. Lee Foote, Associate Professor, Department of Renewable Resources, University of Alberta and Researcher, Adaptive Management Experiment Team
SUBJECT: #133 Roads as Beaver Dams
SYNOPSIS: When it comes to cutting down trees, which came first, the beavers or the loggers? Dr. Lee Foote at the University of
Alberta has been investigating how beavers use roads as dams, and what significance this has for road building and forest management.
AUDIO: Download Audio (mp3 format)
TRANSCRIPT:
Interview starts at 1:13
Intro: The beaver was all but exterminated from the wilds of Canada because of the fur trade. But now, thanks to the overwhelming success of efforts to Reintroduce the species over the last 50 years, beaver populations are at an all time high.
Beavers cut down trees and they made dams. and because of the numbers, they’re a major concern for human engineers in the forests, the people who make roads for pipeline companies, oil and gas exploration and logging operations.
Dr. Lee Foote is an associate professor in the department of renewable resources at the University of Alberta. He and his graduate students have been studying the role of beavers for the AME Team, a group Of scientists researching adaptive forest management.
Dr. Lee Foote
LF: The Adaptive Management Experiment is a collection of scientists from private consulting groups, from academia, from government that work to build large-scale experiments and gain insights that are synthetic in nature, things that tackle problems that are as large as carbon dynamics in wetlands to road infrastructures to cumulative impacts. And I know that Innovation Alberta has had several of the AME folks talk about the great footprint concept that Stan Boutin uses, the ALCES model that Brad Stelfox has advanced quite far, some of the boreal impacts on songbirds that Fiona Schmiegelow has broken new ground in. It’s a great synergistic working team sponsored largely by Alberta-Pacific Forest Industries. And yeah, we’ve learned a lot from each other.CC: WHAT WAS THE QUESTION YOU’RE ADDRESSING WITH THE RESEARCH ON BEAVERS?
LF: It’s a question that’s unfolded over the last three years. We started with the premise that beavers were going to have a large impact on the downstream effects of riparian zones. The unfolding road network in Alberta has crossed lots and lots of streams, just by getting from one resource area to a production area. And when this happens, you interrupt the hydrologic flow. You force surface water to behave in a groundwater manner. You build up ponds on the upstream side. You change the flow patterns. You reduce the flood pulses downstream. And we really expected the riparian zones upstream and downstream to be quite different.
The astute observer from driving around the province will notice that upstream and downstream along certain roadbeds look very different. Often there will be dead standing timber on the upstream side where the water is deeper and its flooded. And lush growth of forests or willow thickets downstream where its moist ground but it’s perfect gardening conditions, not flooded and not dry.
Well we looked really hard. We happened to catch this in the middle of a 4 year drought, so our signal was somewhat muted. But, as we were looking at this, we started changing our question. Roads are there. Roads are important. But the beavers are there in spades. Beavers have come back dramatically in the last 50 years. And their impact on the landscape is probably far in excess of what the roading component is now
Not to say the two aren’t cumulative. But we changed our question to ask, is a roadbed nothing more than a human made beaver dam as far as the impacts on the riparian environment?
Now this work, I have to give credit to two of my graduate students. Katherine Martel and Adelle Flynn have done a bang-up job under some pretty tough conditions looking at the microsite impacts of beavers felling trees, flooding riparian zones, building dams and ultimately, plugging culverts.
And Adele looking at a higher resolution, a larger scale resolution using GIS, or Geographic Information Systems, to inspect the orientation of dams, the spacing, the size of streams, and the width of riparian zones. And beaver are completely reconfiguring some.
CC: WHAT WAS THE CONCLUSION?
LF: Well, we’re in the third year of a two year study, which is not uncommon for Masters students. We haven’t got the ultimate conclusion yet. This is a work in progress.
There’s a nice story here. We can’t call them different, because we find virtually no culvert roadbeds that don’t have beaver influence Beaver are attuned to find flowing water and plug it. They encounter a road bed and what they see is a beaver dam that is 99 percent complete. All they have to do is plug this small one meter culvert and they have their pond built. So consequently, virtually every road bed is also a beaver dam now.
CC: DOES IT MAKE SENSE THEN TO TAKE THE BEAVERS OUT? LF: Sometimes that’s necessary. You remember those nuclear beaver families I talked about. The two year old, what we call the teenagers, are constantly being booted out of Mom and Dad’s lodge. And they have to go somewhere. And they go find a nice neat road bed, a pre-made dam is you will. All they have to do is plug that blankety-blank culvert and they’ve got a dam built. So over and over they fell trees, plug the culverts. They are then classified as a nuisance beaver, and trappers are sent in to take these beavers out. And they do. They’re not wasted. The furs are used because they try trapping during the trapping season. But there’s a net sink to the population here.
That doesn’t mean beavers will be in danger again. What it means is its one of the spin-offs of road networks is they cause a certain removal, a chronic removal of beavers.
CC: WELL IT SOUNDS TOO LIKE IT MAKES IT EASIER FOR THE BEAVER TO MAKE HIS DAM.
LF: Yes, it makes it real easy. That was one of the problems of our study. We couldn’t make a clean distinction between what was and wasn’t a beaver dam. The roads basically became beaver dams.
They function a little differently. The don’t leak the same way. They don’t blow out as often. They’re like a permanent beaver dam on the landscape . But beaver do fell trees near by and they do change the water flow patterns there, so we had to change the study somewhat and look at the impact beavers were having.
And we actually went back in time. If we look at a set of aerial photos from 1949, 1970 and 1999, those were three of our better dates. (In 1949)What we see is virtually no beaver dams on the landscape. A nice narrow forested riparian corridor. Very little road activity and very little power line, pipeline or cut line activity.
1978, we see some human impacts and we see the occasional beaver dams.
1999 what we see is lots of upland impacts, beaver dams scattered throughout, usually 8 to 10 times as many beaver dams on the landscape, riparian zones that are showing the mowing effect of the beavers working on the uplands, the nearby uplands, And so, we can just see both of these things unfolding at the same time.
Now, I know you have a bit of an interest, and your listeners will have a bit of an interest in the riparian buffer strips that the operating ground rules of Alberta forestry require forest harvesters to leave there. And I hate to say, but a lot of those are destined to become beaver food.
If its poplar, it’s probably ultimately going to be felled by beavers. That 60 meter swath on either side of the stream channel, it’s highest and best use probably is as beaver food. They deliver it to the stream as coarse woody debris at just the right rate for insect colonization, they provide nesting cavities for buffleheads and golden eyes. And they build dams that provide habitat for otters and muskrats and dragonflies. It’s this little corridor, this ribbon of biodiversity that runs through sometimes an industrial landscape. And even though they may cost us a little timber, in the long run, beavers are a tremendous friend to our biodiversity system in Alberta.
CC: SO IN THAT SENSE, IT’S REALLY IMPORTANT TO CONTINUE TO MAINTAIN RIPARIAN OR BUFFER STRIPS IN THE FORESTRY OPERATION?
LF: Exactly. That’s one of the functions I think buffer strips provide. They do lots of other things. They provide building material for beavers, they provide a food source for beavers. And you know, they may also keep beaver out of the regenerating plantations. Beavers love nothing more than a nice succulent stand of head high aspen suckers . So , in some ways, we’re baiting the beavers out of there.
Beavers will normally forage up to about 60 meters from the waters edge. They get very ansy beyond that because they’re coyote bait. They’re black bear bait. These are few things that eat beavers. And so they’re foraging range is between 30 and 60 meters from the water where they can fell trees, chew the bark, drag building materials back down the slope to build their dams. And that’s just coincidentally just about the size of our buffer strips.
CC: WHAT WOULD THE PART BEAVERS PLAY IN THE TOTAL ECOLOGY OR THE ECO SYSTEM? WHY ARE THEY IMPORTANT?
LF: I’ll answer this from two different perspectives. First from the forest industry perspective. Beavers are probably one of the most effective reclamation units you’ve got. They provide a stair-step like series of ponds that are water quality enhancement agents. They stop the sediments from run-off from roads or from any harvesting operation or even oil well pads. They give the sediments a chance to settle out the aggregated, flocculated fall out and so the water quality downstream is much higher. They’re good that way.
The other perspective I would take this from is from a broadscale ecological perspective . Beavers are engineers. Beavers engineer habitats for a lot of wetland dependent species. In the short term, I mentioned dragonflies, otters, things like that. In the long term, they provide a level of diversity, as each beaver dam fills up, turns into a wet meadow or gets abandoned, it turns into a wet meadow, moose pasture is what s some people might call it. Willow flats. Eventually the sediments move out. It becomes suitable for colonization again. Trees have grown up along the edge, so it gets reflooded.
So if we could take a time lapse photography from a satellite over time what we would see is a ribbon of creek with little beaver patches popping up and disappearing, popping up and disappearing. So we have spatial variability. We have temporal variability. But we still have a continuity along our riparian zone that lots and lots of species use.
CC: WELL THE REASON YOU’RE LOOKING AT THIS IS TO TRY AND COME UP WITH SOME MANAGEMENT IDEAS FOR PEOPLE WHO ARE IN THE FOREST AND WHO ARE BUILDING ROADS, WHETHER ITS IN OIL AND GAS OR FORESTRY OR WHATEVER. ANY IDEA AT THIS POINT WHAT YOU MIGHT BE ABLE TO SAY TO MANAGERS IN TERMS OF THIS INTERRELATIONSHIP BETWEEN BEAVERS, BEAVER DAMS AND ROAD BUILDING?
LF: Yes. We need to think outside of the box. The standard old culvert crossing just won’t get it in this era of beaverness. They’re going to be plugged and you’re going to have an ongoing headache on your hands.
More and more we see the progressive companies moving to putting in small bridges. And that pretty well thwarts beavers. They’ll try. But it won’t work. So bridges make a lot of sense. Less hydrological interruption. They’re more expensive.
The second thing I would say is consider some really innovative approaches that people haven’t done around here. Like French drains. A French drain is a large cobble substrate that the water can actually move through. And a beaver can’t very effectively plug that.
An interesting piece of natural history. Beavers are tremendously attracted to the sound of running water and a beaver instinctively trie to plug that up. A French drain doesn’t gurgle, so beavers aren’t going to hear that. One researcher put a continuous loop tape player of water sounds on a beaver dam and it just about drove the beavers crazy. They built a six foot wall of mud all the way around it and they couldn’t make it shut up.
CC: WHAT’S LEFT TO DO ON YOUR STUDY?
LF: Well there’s a lot interpretation to do. And get these two wonderful women graduated. I’ll be going up to talk with some of our industrial partners. We’re going to brainstorm. And we’re going to pick their brains. They’re going to pick mine. And we’re going to try and come up with the most innovative approach to problems and opportunities that we can. And try and figure out iwhat happens when beavers come and go. Are we at a current peak of beaver numbers or is this just a one time blip or are they here to stay at this level? This re-colonization may be a bit of overshooting of beaver populations.
The other thing I’ m interested in and we’ll try to tease out is to model this beaver to the entire northeastern quadrant of Alberta and see what benefits and costs beavers bring to humans on the landscape.
CC: THANK YOU VERY MUCH.
LF: Oh it’s been great. Thanks Cheryl
Dr. Lee Foote is an associate professor in the Department of Renewable Resources at the University of Alberta and a researcher with the Adaptive Management Experiment Team.
FEATURED LINK: Visit the AME (Adaptive Management Experiment) website
FEATURED LINK: Visit Dr. Lee Foote's home page