Fig. 1.
Map of southern Norway with the locations of the hollow oaks (n = 40). The symbols show isolation category: solitary (high isolation) and aggregated (low isolation).
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.