Many of the trees on both sites have been girdled, their bark removed in a full circle around the tree, near the bottom, by mice. This either kills the trees or forces them to shoot up new stems, which they can only do so many times.
“The mice are the big culprits,” said Farnham, a Mankatoan.
Farnham has tried to keep the mice away by wrapping a sort of tape around the trunk of trees at a Highway 14 site, along Good Counsel Hill. It works, but it would be far too time-consuming for Farnham to wrap hundreds of trees. She has already spent many hours on this hill removing invasive species like buckthorn to give the trees a chance.
Hagen said mice do well in drought, which helps to explain their numbers.
The Million Tree Project was always an experiment to learn what sort of plantings worked best in each place, Hagen said. And some of the trees have survived. If they grab a foothold, nature may take over and expand the forest.
Hagen said it would be best to wait until the drought is over before trying again.
Farnham said the mice could perhaps be counter-acted with barriers, but that, again, would take a lot of work.