Scientific Definitions and Measurements of Second-Growth, Mature, and Old-Growth Forests

Abstract

We examined US scientists’ (1) use of second-growth, mature, and old-growth forest in scientific publication titles, (2) definitions of second-growth, mature, and old-growth forest, and (3) sampling methods in second-growth, mature, and old-growth forest. “Second-growth forest” (55 titles) and “mature forest” (40) experienced the most frequent use in the 2010s. “Old-growth forest” (247) had the most use in the 1990s. Definitions of second-growth forest originated from successional theory and were consistent across scientists. Definitions of mature forest lacked consensus. Definitions of old-growth forest increased in complexity as scientists integrated biological, social, and political factors. Soil was the most frequent abiotic factor measured in mature and old-growth forests. In second-growth forests it was dead organic matter. Trees were the most common life form measured in all forests. The results show that researchers would benefit from a clearer differentiation between second-growth and mature forest and a formal definition for mature forest.