The relative density of forests in the United States

A relative stand density assessment technique, using the mean specific gravity of all trees in a stand to predict its maximum stand density index (SDI) and subsequently its relative stand density (current SDI divided by maximum SDI), was used to estimate the relative density of forests across the United States using a national-scale forest inventory. Live tree biomass (dry metric tons) varies widely across the US with the largest amounts in the Pacific Northwest region followed by the hardwood forests of the eastern US. In contrast, the range of relative density appears to be less disparate with numerous forests across the US having densities as high as areas in the Pacific Northwest. Overall, the large-scale assessment of relative density indicates that the majority of forests in the US are fully occupied in a rather contiguous pattern except for areas of the western US.