Chinese fir(Cunninghamia lanceolate[Lamb.]Hook.)is a fast-growing species which is not only important as a timber-supplier,but also as an available sink for carbon(C)storage in biomass.Stand age and density are two cr...Chinese fir(Cunninghamia lanceolate[Lamb.]Hook.)is a fast-growing species which is not only important as a timber-supplier,but also as an available sink for carbon(C)storage in biomass.Stand age and density are two critical factors that can determine tree C sequestration as interrelated drivers through natural self-thinning.C.lanceolate were planted using 1-year-old bare-root seedlings at the initial density of 1800 stems ha^(-1)in a 15-ha montane area of Hunan Province,China in 1987.The plantation was thinned twice 10 and 20 years after planting to leave trees of437.5±26.6,675.0±155.2 and 895.8±60.1 stems ha^(-1)as low,medium,and high densities,respectively.Tree height and diameter at breast height(DBH)were measured every2 years beginning from 23 years(2009)to 31 years(2018)after establishment,timber volume(TV)and biomass C were estimated accordingly.We did not find any interactive effect of age and density on any variables except for height.Both TV and biomass C increased with stand age or decreased in higher densities.The allometric heightDBH relationship can be fitted by an exponential risingto-maximum model with higher maximum value over time.The decline of biomass C along density fit with the inverse first-order polynomial model which indicated that at least1300-1500 stems ha^(-1)may be needed to maximize TV and biomass C for a longer term over 20 years.Therefore,to control the density to a reasonable level,over 1300 stems ha^(-1)in a rotation over 20 years old will be practical for tree biomass C in Chinese fir plantations.展开更多
基金funded by Research on High-efficient management technology of large-size timber of Cunninghamia laceolata in the National Key R&D Program(Grant Number 2016YFD0600301)。
文摘Chinese fir(Cunninghamia lanceolate[Lamb.]Hook.)is a fast-growing species which is not only important as a timber-supplier,but also as an available sink for carbon(C)storage in biomass.Stand age and density are two critical factors that can determine tree C sequestration as interrelated drivers through natural self-thinning.C.lanceolate were planted using 1-year-old bare-root seedlings at the initial density of 1800 stems ha^(-1)in a 15-ha montane area of Hunan Province,China in 1987.The plantation was thinned twice 10 and 20 years after planting to leave trees of437.5±26.6,675.0±155.2 and 895.8±60.1 stems ha^(-1)as low,medium,and high densities,respectively.Tree height and diameter at breast height(DBH)were measured every2 years beginning from 23 years(2009)to 31 years(2018)after establishment,timber volume(TV)and biomass C were estimated accordingly.We did not find any interactive effect of age and density on any variables except for height.Both TV and biomass C increased with stand age or decreased in higher densities.The allometric heightDBH relationship can be fitted by an exponential risingto-maximum model with higher maximum value over time.The decline of biomass C along density fit with the inverse first-order polynomial model which indicated that at least1300-1500 stems ha^(-1)may be needed to maximize TV and biomass C for a longer term over 20 years.Therefore,to control the density to a reasonable level,over 1300 stems ha^(-1)in a rotation over 20 years old will be practical for tree biomass C in Chinese fir plantations.
