One of the main elements of dendrochronological standardization is the removal of the biological trend, i.e., the progressive decline of ring width along a cross-sectional radius that is mostly caused by the corresponding increase in stem diameter over time. A very common option for removing this biological trend is to fit a modified negative exponential curve to the ring-width measurements. Because this method has numerical and conceptual drawbacks, we propose an alternative way based on a simple assumption, namely that a constant basal area increment is distributed over a growing surface. We then derive a mathematical expression for the biological trend, which can be easily calculated and used for dendrochronological standardization. In turn, this "C-method" provides an empirical test of existing theories on life-long progression of tree basal area increment. The proposed method was applied to tree-ring records from ponderosa pines (Pinus ponderosa Douglas ex P.Lawson & C.Lawson) located at the G. A. Pearson Natural Area in northern Arizona, U.S.A. Master ring-index chronologies built with the C-method reproduced stand-wide patterns of tree growth, and are therefore preferable for ecological applications. Other advantages of the C-method are that it is theoretically derived, it is applicable to individual series, and it does not require fitting a growth curve using nonlinear regression.