Why is the outside of the German townhouse black wood walls?

According to the query black wood used for building exteriors, or cool, it is said that the "fire wood" originated in Japan 1600 years ago, when Japan's extreme lack of wood, the good thing is that the proximity of the coastline, the beach often drift drift driftwood, but also to avoid the use of the process of insects and ants disaster, the Japanese invented this kind of wood treatment with fire! wood treatment.