Abstract
We analyzed 45-yr data collected from three ponderosa pine (
Pinus ponderosa Lawson & C. Lawson) levels-of-growing-stock installations in Oregon (OR) and northern California (CA), USA, to determine the effect of stand density regimes on stand productivity and mortality. We found that periodic annual increment (PAI) of diameter, basal area (BA), volume, and aboveground dry weight were significantly related to Stand Density Index (SDI) and stand age at start of period; the quadratic trends varied among sites. Precipitation departure from the normal for each period explained a significant amount of residual variation in all PAI variables but diameter. BA production did not change significantly as SDI exceeded 270 trees ha
-1 at the OR sites and 320 trees ha
-1 at the CA site. Stand productivity was the highest at Elliot Ranch (CA) and the least at Blue Mountains (OR). A similar trend held in growth efficiency under lower stand densities (SDI < 600). Most of the mortality was caused by
Dendroctonus bark beetles in stands that exceeded SDI 500. Limiting SDI was about 900 although plots at Elliot Ranch reached much higher than that. The results demonstrate that silvicultural control of stand density can be a powerful tool for reducing bark beetle-caused mortality without sacrificing stand productivity.
Keywords
Level-Of-Growing-Stock study,
stand density index,
mortality
Citation
Zhang, Jianwei; Ritchie, Martin W.; Maguire, Douglas A.; Oliver, William W. 2013. Thinning ponderosa pine (
Pinus ponderosa) stands reduces mortality while maintaining stand productivity. Can. J. For. Res. 43:311-320.
