Analysis on the Growth Rhythm and Cold Tolerance of Five-Year Old Eucalyptus benthamii Plantation for Bioenergy

Abstract

A research plot of Eucalyptus benthamii was planted to evaluate this species’ ability to supply the emerging bioenergy markets that are developing in the southern U.S. The plot was planted in two different densities to investigate the growth parameters and the cold tolerance. The stand was measured annually through five growing seasons. The results indicated that the growth difference among the young E. benthamii was noticeable. For example, the maximum and minimum value of five-year old trees at diameter breast height (DBH) was 27.9 centimeters and 1.27 centimeters; and the maximum and minimum value of tree height was 22.86 meters and 2.44 meters, respectively. The yearly change in DBH and height of E. benthamii had significant differences. The average annual survival rates of E. benthamii had differences under the two planting densities (1650 trees ha−1 and 1237 trees ha−1). The densities also had effects on the height and DBH growth of E. benthamii. The average DBH and height of 1650 trees ha−1 plantation were 11.18 centimeters and 15.03 meters, and the average DBH and height of 1237 trees ha−1 plantation were 13.46 centimeters and 16.28 meters. The volume per hectare of 1650 trees ha−1 and 1237 trees ha−1 plantation were 111.45 cubic meters and 101.15 cubic meters, respectively. Average diameter growth was almost 2.54 centimeters per year and average height growth was over 3 meters. E. benthamii plantations were considered tolerant to −7.4 degrees Celsius and a cold spell during early 2014 (−11.3 degrees Celsius for two consecutive nights) killed the plantation. The growth of E. benthamii also varied depending on surrounding conditions. The difference in growth of row seven versus row one was a good example. The reason probably was that row seven was adjacent to a loblolly pine plantation and row one was next to an open field.