This paper describes the removal of extraneous color from increment cores of conifers prior to reflected-light image analysis of tree rings. Ponderosa pine in central New Mexico was chosen for study. Peroxide bleaching was used as a pretreatment to remove extraneous color and still yield usable wood for image analysis. The cores were bleached in 3% peroxide raised to pH 12 and heated to 60° C, and then they were soaked in 95% ethanol and rinsed in water. The cores were dried slowly to avoid checking or cracking. This treatment removed heartwood color while leaving the wood reasonably sound. Wood reflectance and latewood width were measured using reflected-light image analysis. For dendroclimatic modeling, best-subsets regression was used to determine the strongest predictive model, which was May-September rainfall using latewood reflectance and latewood width. The ability to dendroclimatically model and reconstruct summer precipitation is contingent on having latewood reflectance (density) measurements, and reconstructing summer precipitation in the Southwest will enhance paleoclimatology of the region. Image analysis with reflected white light is thus closer to being more widely applicable in dendrochronology
