A long-term evaluation of biomass production in first and second rotations of Chinese fir plantations at the same site

Abstract

Since the 1970s, a long-term research project has been conducted to monitor the changes in primary productivity of Chinese fir plantation at Huitong Ecosystem Research Station, Hunan, China. Standing biomass and net primary productivity (NPP) of the plantation were investigated at four times (7, 11, 14 and 18 years old) in two successive rotations on the same site. The mean individual tree biomass and stand biomass in the second rotation were reduced by ∼18, 17, 7 and 3 per cent in 7-, 11-, 14- and 18-year-old stands, respectively, compared with the first rotation. In the first rotation, annual NPP was higher in the 7-, 11- and 14-year-old stands, but lower in the 18-year-old stands, compared with those in the second rotation. The proportion of biomass in stem, canopy (branch and leaf) and root was ∼80, 13 and 7 per cent and 64, 20 and 16 per cent at the later stages of the stand development (≥14-year old) in the first and second rotations, respectively. The results suggests that relative large dry matter found in root systems in the second rotation increases the capacity of Chinese fir to exploit the soil for nutrient and water resources, which facilitates tree growth and productivity. © Institute of Chartered Foresters, 2011. All rights reserved.