"We have to tamper with nature. We must manipulate it to suit our pictures," Tarkovsky told his crew when they worked on The Sacrifice on Gotland. Some of the scenes including the very last one were filmed at Närsholmen peninsula, a nature reserve with  savanna-like landscape and rich birdlife. The Nordic nature is beautiful indeed but capricious, and some of the scenes had to be recreated later in the studio.  

Bonus fact: in 2011, the famous Swedish singer Lykke Li filmed the video for her song "I Follow Rivers" on Närsholmen. The music video was directed by Tarik Saleh and features Li and actor Fares Fares.

Sources: “Daily Rounds with Andrej Tarkovskij” by Lars-Olof Löthwall, Wikipedia