'A line called the 50 deg. summer isotherm  closely follows this northern limit of forest growth'
Treeline
WAY UP NORTH: A line called the 50 deg. summer isotherm  closely follows this northern limit of forest growth
A line called the 50 deg. summer isotherm  closely follows this northern limit of forest growth
A line called the 50 deg. summer isotherm  closely follows this northern limit of forest growth
WAY UP NORTH
Treeline
WAY UP NORTH