North American beaver (Castor canadensis) in the Northwest Territories, Canada. Credit: Dr. Helen Wheeler, Anglia Ruskin University A study has provided new evidence of beavers' expansion into the Canadian Arctic by dating the changes they have made to the tundra landscape as they spread northward. Published in the journal Ecosphere , the research combines tree-ring analysis, or dendrochronology, with satellite imagery of surface water to pinpoint the spread of the North American beaver (Castor canadensis) in a remote part of Canada's Northwest Territories. Beavers are ecosystem engineers , capable of changing landscapes through the construction of dams, which can alter the stability of permafrost and impact the flow of water, fish populations and local livelihoods. Beavers reshape and record the tundra Led by researchers from Anglia Ruskin University (ARU) in Cambridge, England, this new study shows that beavers leave behind a datable environmental record.…