Comparison Study on Ring Characteristics and Basic Density of Pinus elliottii and Pinus caribaea Wood

The 19-year-old Pinus elliottii and Pinus caribaea in Hepu, Guangxi were tested. The tree ring width, latewood ratio and wood basic density of 2 pines were compared by the method of different diameter class selecting. The results showed that the ring width did not reach the significant difference, annual ring width of P. elliottii in first 10 years was longer than that of P. caribaea. The growth of P. caribaea in the last 9 years was equal or surpassed that of P. elliottii. The latewood ratio of 2 pines increased rapidly in the first 10 years and began to be relatively stable after 10 years. The latewood ratio of P. elliottii was significantly higher than that of P. caribaea, all diameter classes reached significant difference level. The wood basic density of 2 pines did not reach the significant difference. The wood basic density of P. elliottii in 1–7 ring segments were lower than P. caribaea, and 8–19 ring segments were higher than P. caribaea. The average wood basic density of full diameter classes of P. elliottii was slightly lower than that of P. caribaea. According to the latewood ratio and wood basic density, the transition age from juvenile to mature wood of P. elliottii was 5–6^th years, and that of P. caribaea was 7–8^th years. The proportion of juvenile in P. caribaea was higher than P. elliottii 10%, but the latewood ratio of juvenile was similar. The radial trend of ring width, latewood ratio and wood basic density of P. caribaea was more stable than Slash pine.