• Fraver, Shawn
  US Forest Service
  
• Bradford, John
  US Forest Service
  
• Palik, Brian J.
  US Forest Service
  

Accurate tree ages are critical to a range of forestry and ecological studies. However, ring counts from

increment cores, if not corrected for the years between the root collar and coring height, can produce sizeable

age errors. The magnitude of errors is influenced by both the height at which the core is extracted and the growth

rate. We destructively sampled saplings and small trees of red pine (Pinus resinosa Ait.) and combined withinand

between-tree cross-dating to determine accurate rings counts and radial growth rates for 11 stem sections of

each sample. We developed regression models to estimate age adjustment as a function of coring height and

radial growth rate. We compared candidate models using corrected Akaike’s information criterion scores, and

we evaluated model performance by jackknife permutations. Application of our best-fit equations clearly

improved age estimates: compared with unadjusted ring counts, our adjusted age estimates had normally

distributed errors centered near 0, lower standard deviations, and a narrower range of values. Thus, these

equations can be used to adjust ages of cored, mature trees occurring in these same settings. The methods used

here may be applied to other shade-intolerant or mid-tolerant species where improved tree establishment dates

are needed.