The trees were hung up with ropes. This road sat 6 miles from the Russian border, so when looking down from observation airplanes, the road would be disguised.
It was intended to be viewed obliquely (slanted) not directly from above. The suspended trees would conceal enough of the road to make it difficult to identify visually when flying past, or from surveillance photos taken from aircraft. Camouflage is designed to break up the shape of something against the background, this would have been effective within certain limits.
The photo is from the Richard Stallman (RMS) visit to Cyprus. We are both staring and not starting at the ancient settlement of Choirokoitia. You can listen to his speech here