EQUATIONS FOR PREDICTING ABOVEGROUND BIOMASS OF PLANT-SPECIES IN EARLY SUCCESSIONAL FORESTS OF THE WESTERN CASCADE RANGE, OREGON

We present a set of 152 regression equations that predict the above-gr ound biomass of 38 herb, shrub, and tree species common on early succe ssional (clearcut) sites in the western Cascade Range of Oregon. For m any of these species, biomass relationships have not been modeled prev iously or have not been modeled for early successional sites. Biomass of herbaceous taxa is best predicted by cover, while biomass of woody species is best predicted by stem diameter and/or length. We discuss h ow relationships between biomass and plant size vary with site age amo ng species of diverse growth form and life history. We supplement best -fit models with alternative equations that are easier that are easier to implement in the field of that are less sensitive to sources of va riation associated with time since disturbance. To minimize the misapp lication of equations, we report the dimensional ranges of all plant v ariables measured, whether or not they are explicitly modeled.