coupe sombre

Etymology
From woodcutting; the idea being that the forest is still dense and dark, because it was only lightly felled.

Noun

 * 1)  light felling, thinning of the trees
 * 2)  drastic cuts

Usage notes

 * This idiom is often misunderstood to mean "heavy felling" (for which would be the right term), whence the figurative sense.