Actually the opposite. Most woodland managers now recognise the value of leaving fallen trees to rot as the micro environment they generate fosters growth of fungus and its been found these fungi growing underground link with the roots of the trees and help provide nutrients and other benefits. After the great storm in 87' they subsequently found that most woods recovered better if they fallen trees were left where they fell.
Look like a Lime. Its a shame its not in flower as the perfume from the lime in full flower is amazing, not a tree like it. If you are in a wood where one is flowering the breeze carries it everywhere. The wood from lime is the best for carving you can get as it has little grain and is relatively soft. They grow to a large size and i think the one which you also showed which was large and had many top shoots is also a lime.
Great Danes are lovely dogs but sadly don't live long. I had a Great Dane in Nepal years ago but she left as she had to get back to work.