Clues to wood quality and production from analyzing ring width and density variabilities of fertilized Pinus taeda trees

Tree growth and wood density are influenced by forest management. Nevertheless, few studies have evaluated their variability responses to fertilizer treatments at inter-annual, inter-tree and stand-production levels. Therefore, the annual ring width (RW) and density (RD) of sixty 17-year-old-Pinus taeda trees fertilized with six doses of composted pulp-mill sludge (CPMS) were analyzed. Ten trees for each treatment were felled and from which wood discs were taken at different trunk heights. The annual RW and RD were provided by X-ray microdensitometry, synchronized and the trunk basic specific gravity (SG_B) and biomass calculated. The effects of CPMS treatments were explored using interaction of variables RW and RD with cambial age, diameter, trunk SG_B and biomass production. Trees treated with CPMS grow faster, increasing their biomass (up to 108%), presenting lower wood density values (significant up to the 6th year) and reaching the mature wood later than untreated trees. Furthermore, the potential use of RW and RD in allometric equations showed good accuracy to predict trunk SG_B and biomass. Altogether, our results indicated that ring width and density revealed the impacts of fertilization treatment on wood quality and production. Our study also provides useful information for forest managers on the fertilization monitoring process.