关键词: 碳储量, 固碳能力, 可变参数, 生长模型, 连年生长量, 平均生长量, 气候因子

Abstract:

Objective: Developing growth models of carbon storage in tree layers for five major plantation types in China, i.e., Chinese fir, popular, eucalyptus, larch, and masson pine, determining the stand age with maximum average carbon growth, and analyzing difference of and climate effect on carbon sequestration capacity would provide scientific basis for increasing carbon sequestration capacity of plantations and decision-making of sustainable forest management. Method: Based on the carbon storage data of 8 520 sample plots from the 9^th national forest inventory of China, the growth models of carbon storage in tree layers for five major plantations were developed through using weighted nonlinear regression method and variable parameter model, the impacts of two climate factors, i.e., mean annual temperature (MAT) and precipitation (MAP), to model parameters were analyzed, and the difference of carbon sequestration capacity in tree layers among five plantations was compared. Result: The mean prediction errors of growth models of carbon storage in tree layers for five types of plantations developed in this study are less than 5%, and total relative errors are all less than 3% for both calibration and cross-validation. The mean carbon growth of larch, masson pine, Chinese fir, popular, and eucalyptus plantations reach to the highest 1.50, 1.85, 2.10, 2.96, 6.97 t?hm^?2, respectively at 24, 16, 12, 6, and 2 years old of stand age. Comparison to larch plantation, the highest mean carbon growth in tree layers of masson pine, Chinese fir, poplar and eucalyptus plantations are 1.23, 1.40, 1.97 and 4.65 times, respectively. The models were used to analyze the influence of climate factors on carbon storage in tree layers. The results showed that 1 ℃ decrease in MAT could result in 7.6%, 4.5%, 4.0% and 3.0% decrease of annual mean carbon growth for popular, masson pine, eucalyptus, and larch plantations, respectively; and 100 mm decrease in MAP could result in 5.8% decrease of annual mean carbon growth for larch plantation, but increase in some extent for poplar and eucalyptus plantations. Conclusion: The carbon sequestration capacity in tree layers of major five types of plantations was successively eucalyptus, popular, Chinese fir, masson pine and larch, which was affected by MAT and MAP to varying degrees. The most significant effect is to poplar plantation, followed by larch, Masson pine and eucalyptus plantations, but there is no significant effect to Chinese fir plantation. To maximize the carbon sequestration potential of plantations in China, we need to determine reasonable management cycle referring to the growing process of carbon storage, and do efforts for developing eucalyptus and poplar plantations based on balancing regional development.

Key words: carbon storage, carbon sequestration capacity, variable parameter, growth model, annual growth, mean growth, climate factor