Germany have similar things though I do not know of a general nature corridor project. There are rather project specific corridors i.e for wildcat (https://www.

Germany have similar things though I do not know of a general nature corridor project. There are rather project specific corridors i.e for wildcat (https://www.bund.net/fileadmin/user_upload_bund/bilder/wildkatze/wildkatzen_projekt_korridore_karte.jpg https://www.bund.net/fileadmin/user_upload_bund/bilder/wildk...) or the mentioned german green belt. These are smaller than the thing you link in Poland, however at least the green belt program is an initiative for almost 100% natural reserve (i.e no agriculture or forestry at all) in that area which I believe most other corridors are not. Also, there are lots of local projects to protect old tree alleys along smaller streets etc. that serve a similar purpose. https://en.wikipedia.org/wiki/German_Green_Belt https://en.wikipedia.org/wiki/German_Green_Belt