Years back I stumbled upon an article comparing the art of the Romantic period in France and Germany. The author concluded that the French Romantic art tended to celebrate the "savoir vivre" while the German Romanticists revelled in the "savoir mourir". This idea (though not to be generalised) is rather intriguing.
Taking a look at the German landscape art of the late 19th and early 20th century, the "savoir mourir" is still a valid aspect of its multiple facets. Be it Arnold Böcklin with his variants of the "Isle of the Dead" or Walter Leistikow with his landscape paintings of the Mark Brandenburg, their landscape is distinctively melancholy in its atmosphere. They are landscapes that don't want to portray a specific landscape as much as they want to evoke a certain sentiment for the audience to associate and feel while viewing their artwork.
Same goes for the works of the two Art Nouveau artists, Hermann Hirzel and Georg Jahn, and their landscape illustrations for the magazine "Teuerdank" (published 1901-03 by Fischer & Franke in Berlin and Düsseldorf). - Hirzel's landscapes, entitled "Stimmungen" ("Moods"), are not serene at all. They show a quiescent world with an air of loneliness, of melancholy. They are beautiful, but sad, and this even though the artist did not paint his landscape in gloomy colours. It's the motifs and their "Inszenierung".
Georg Jahn's views of the coast and sea are equally un-lively: showing a barren land, buffeted by wind and waves. It's not a welcoming or forgiving landscape. It existed long before men travelled it, and will exist long after the extinction of mankind it. It's the old idea of death, of a Memento Mori that is part of the landscapes' inherent moods. It's the "savoir mourir" that becomes apparent in these works, the decision of the artists not to draw a landscape evoking happiness but a sad longing.