Carbon storage of exotic slash pine plantations in subtropical China.
Exotic conifer trees have been extensively planted in southern China because of their high apparent growth and yield. These fast-growing plantations are expected to persist as a considerable potential for temporary and long-term carbon sink to offset greenhouse gas emissions. However, information on the carbon storage across different age ranges in exotic pine plantations is often lacking. We first estimated the ecosystem carbon storage across different age ranges of exotic pine plantations in China by quantifying above- and below-ground ecosystem carbon pools. The carbon storage of each tree component of exotic pine (Pinus elliottii) increased significantly with increasing age in Duchang and Yiyang areas. The stem carbon storage except <10 years in Ji'an areas was the largest component among all other components, which accounts for about 50% of the total carbon storage followed by roots (∼28%), branches (∼18%), and foliage (∼9%). The mean total tree carbon storage of slash pine plantations for <10, 10-20 and 20-30 years across three study areas was 3.69, 13.91 and 20.57 Mg ha<1, respectively. The carbon stocks in understory and forest floor were age-independent. Total tree and soil were two dominant carbon pools in slash pine plantations at all age sequences. The carbon contribution of aboveground ecosystem increased with increasing age, while that of belowground ecosystem declined. The mean total ecosystem carbon storage of slash pine plantations for <10, 10-20 and 20-30 years across China was 30.26, 98.66 and 98.89 Mg ha-1, respectively. Although subtropical climate in China was suitable for slash pine growth, the mean total carbon stocks in slash pine plantations at all age sequences from China were lower than that values reported in American slash pine plantations.