Fig. 2From: Variable retention harvesting in Great Lakes mixed-pine forests: emulating a natural model in managed ecosystemsAge structures for old-growth red pine-dominated stands in MN, USA, showing a variety of forms, including broadly single-cohort, two-cohort, and three-cohort structures. Dates are known fire occurrences. Solid triangles denote known fire dates in each stand; open triangles denote known fire dates from nearby stands. Redrawn from Fraver and Palik 2012Back to article page