Bark Thickness Equations for Mixed-Conifer Forest Type in Klamath and Sierra Nevada Mountains of California

Abstract EN

We studied bark thickness in the mixed-conifer forest type throughout California.

Sampling included eight conifer species and covered latitude and elevation gradients.

The thickness of tree bark at 1.37 m correlated with diameter at breast height (DBH) and varied among species.

Trees exhibiting more rapid growth had slightly thinner bark for a given DBH.

Variability in bark thickness obscured differences between sample locations.

Model predictions for 50 cm DBH trees of each species indicated that bark thickness was ranked Calocedrus decurrens > Pinus jeffreyi > Pinus lambertiana > Abies concolor > Pseudotsuga menziesii > Abies magnifica > Pinus monticola > Pinus contorta.

We failed to find reasonable agreement between our bark thickness data and existing bark thickness regressions used in models predicting fire-induced mortality in the mixed-conifer forest type in California.

The fire effects software systems generally underpredicted bark thickness for most species, which could lead to an overprediction in fire-caused tree mortality in California.

A model for conifers in Oregon predicted that bark was 49% thinner in Abies concolor and 37% thicker in Pseudotsuga menziesii than our samples from across California, suggesting that more data are needed to validate and refine bark thickness equations within existing fire effects models.