young trees growing in protective tubes in the siebengebirge forest.

europe germany park young trees growing protective tubes reforestation efforts siebengebirge forest klosterruine heisterbach agriculture beech botany care cologne cologne forests covering cultivated cultivation cylinder ecological efforts environment environmental europe growth protection regeneration forestry germany green landscape growing heisterbach nature conservation reserve restoration outdoor nature park plant plantation plastic reforestation project row seedlings shelter forest spring sustainable tree protection tubes woodland