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Table 1 Summary of forest structure and environmental data from 1923 compared to 2001–2010. The smaller size classes (15 to 30 and 30 to 60 cm DBH) were adjusted from one third of the plots (those sampled in 1936) to bring the density down to estimated 1923 levels, as described in Methods. The environmental variables were averaged across all historical sample transects and FIA plots (2001–2010) using long-term average values from 1981 to 2010

From: Historical and modern landscape forest structure in fir (Abies)-dominated mixed conifer forests in the northern Sierra Nevada, USA

Forest structure and data 1923 2001–2010
Trees per hectare 15 to 30 cm DBH 45.1 180.2
Trees per hectare 30 to 60 cm DBH 40.4 113.1
Trees per hectare 60 to 91 cm DBH 20.5 24.7
Trees per hectare >91 cm 22.0 8.7
Total trees per hectare 128.0 326.7
Total basal area (m2 ha−1) 43.1 42.1
Mean Abies:Pinus ratio 0.6 0.5
Mean elevation (m) 1840.8 1740.0
Mean annual precipitation (mm) 1402.8 1427.0
Mean annual temperature (°C) 15.4 16.3