Eucalyptus forests are grown in many parts of the world for their commercial value and use in construction projects. Density management becomes im- portant as a means to attain the management goals in these forests. Changes in canopy and tree crown structure were quantified for Eucalyptus urophylla x E. grandis forests at different ages to determine when canopy closure occurs and the onset of competition begins. Site index was developed for these forests to determine whether site quality affects the canopy structure. Site index had little effect in the forests sampled, with the forest canopy on the better sites becoming slightly more elongated. Based upon crown projection ratio and crown diameter： dbh （diameter at breast height） ratio, it appears that crown closure occurs by age 4 years in these forests. The age at which this occurs was also checked and verified with the evaluation of relative spacing, RS （the ratio of the mean distance between trees to the average dominant height of the stand）. The RS value displayed a rapid decline until age 4 years, and then became relatively flat through age 21 years. The rapid height growth during the first 3 years with no change in density accounted for this rapid decrease. By age 4 years, reductions in the number of trees due to mortality began to have more of an influence on this value, resulting in a more gradual de- cline. The implications for management are discussed.
Carbon （C） stocks and sequestration rates were determined for oak-hickory forests in Ohio, USA. The models we developed show that the patterns of C sequestration rates follow what we expect in total and merchantable volume increment. The current annual increment （CAI） and the mean annual increment （MAI） peaks at ages 23 and 46 years, respectively, for total aboveground C. The peak CAI and MAI for the aboveground C peaks at ages 26 and 53 years, respectively. The 5-year periodic MAI for both total aboveground C and aboveground portion of merchantable trees occurs at age 30 years, occurring simultaneously with the 5-year periodic MAI for total and merchantable volume. Knowing that C sequestration occurs in similar patterns to volume growth is helpful in transitioning from traditional volume-based management to carbon-based management.
