This postcard depicts a haven of outdoor activity. There are many options for outdoor enthusiasts. In total 34 bikes rides, 71 hiking trails, 26 long distance hiking trails, 7 pilgrim trails.
Otherwise I found it difficult to find much information about this area. Even the German Wiki entry only makes the most cursory remarks. The Gutach Valley is between 250-850 m above sea level with 2.300 inhabitants. Along with the villages of Kirnbach (near Wolfach) and Reichenbach (near Hornberg), Gutach is the home of the Bollenhut, a traditional ladies’ hat topped with pom-poms, which is a symbol for the Black Forest as a whole. The Gutach Valley is a side valley of the Kinzig valley, which the Black Forest Railway runs through between Hausach and St. Georgen. The railway runs through spectacular scenery, the route is 150 km long, ascends 650 metres from lowest to highest elevation, and passes through 39 tunnels and over 2 viaducts. It is still the only real mountain railway in Germany to be built with two tracks.
References
https://www.black-forest-travel.com/gutach/
https://en.wikipedia.org/wiki/Black_Forest_Railway_(Baden)
https://www.gutach-schwarzwald.de/
https://www.schwarzwald.com/gutach/
https://www.outdooractive.com/en/bicycle-rides/gutach-schwarzwaldbahn-/bicycle-rides-in-gutach-schwarzwaldbahn-/2501727/