Formica lemani does look like Lasius niger, but is a litle paler. Also the odour of the nest from F. Lemani seems to be stronger, according to the antblog website.
The typical habitat for these ants is mainly heatland, close to trees. The nest on the photo’s below was found near Olsberg in the Hochsauerlandkreis, Germany. Several ants were bringing nest materials under this trunk. This location was destroyed during a storm in 2006.
