Generalized biomass equations for jack and red pine in the Lake States

Abstract

The biomass of 76 jack pine (Pinusbanksiana Lamb.) trees (29 stands) and 72 red pine (P. resinosa Ait.) trees (28 stands) from throughout the northern Lake States was determined. All trees were from even-aged, unthinned plantations ranging from 20–61 years old; site indexes represented nearly the complete range for these species. Individual tree component weights (foliage, live branches, dead branches, stem wood, and stem bark) were regressed against dbh and tree height using the nonlinear form Bt = aDbHc. Stand biomass was also estimated with stand basal area and mean height of dominant and codominant trees using the equation form Bs = a + b(B) + c(Hs) or a + b(B)(Hs). The equations were tested in two additional stands of red pine and two of jack pine and by comparison with literature values. Individual tree equations were most accurate for estimating bole components and the total tree and less accurate for foliage and branches. The standard error of the estimate divided by mean weight ranged from 0.06 to 0.17 for bole components, from 0.21 to 0.28 for live crown components, and from 0.43 to 0.49 for dead branches. For all components, jack pine equations were slightly less precise than those for red pine. The individual tree equations appear to be applicable over a wide geographical area and usable for both natural stands and plantations. The equations appear to be valid for the majority of unthinned stands in the age range of 20–50 years. The stand equations, while less precise than individual tree estimates, should give reasonably accurate estimates of stand biomass components in most situations.