【Objective】Carbon from the forest plays a dominant role in contributing the development to terrestrial ecosystem. Therefore, the purpose of this study is to predict the carbon sink potential of artificial trees by determining their carbon density and value-added carbon storage potential. The results of the study can further improve the structure of the artificial main forest age groups, improve the sustainable management levels of the forest, provide scientific basis for increasing the artificial tree forest unit area, and achieve the goal of increasing the amount of foreign exchange in China.【Method】This study applied the data of area and volume of the dominate tree species in China. The data are all from the 8th (2009-2013) and the 9th (2014-2018) national forest inventory data of China. Moreover, adopted the IPCC volume-biomass method to calculate the carbon storage and carbon density of the six main artificial arboreal forest. Meanwhile, the changing patterns and age group structure characteristics of the carbon storage and density of artificial arboreal forests in China were also analyzed between the two inventories. The aim of this step was to comprehensively analyze and evaluate China's artificial forest under age structures of carbon sequestration function; furthermore, the fitted unit area accumulation-forest-age logistic regression growth equation was applied and the IPCC volume-biomass methods were combined to calculate the accumulation of different ages of each dominant tree species after decades. The purpose was to estimate the data of carbon storage and carbon density of China's existing artificial arboreal forest in future stages.【Result】During the two inventory periods, the total carbon storage of the main artificial forest increased by 498.81 Tg, with an average annual increase of 99.76 Tg. The carbon storage from the highest to the lowest forest age groups in China was in the following order: over-matured forests (439.19 Tg) > mature forests (426.43 Tg) > near-mature forests (359.75 Tg) > middle-aged forests (292.34 Tg) > young forests (105.15 Tg). Carbon density from the lowest to the highest age groups in China were in the following order: over-matured forests (59.17 Mg/hm2) < young forests (169.12 Mg/hm2) < mature forests (178.13 Mg/hm2) < near-mature forests (190.38 Mg/hm2) < middle age forests (348.09 Mg/hm2). With regard to the future carbon sequestration capacity of artificial forests in China, the analysis results predict that the carbon storage and density of artificial arboreal forests based on current data will increase to 1 716.27 Tg and 36.51 Mg/hm2, with an increase of 92.92% and 93.17%, respectively, compared with the values in 2015.【Conclusion】The carbon storage of the six main artificial forest increased significantly between the two inventories. Carbon storage shows a linear positive increase trend, while carbon density does not show a linear increase due to the effect of accumulation of the area and the volume. Moreover, by the year of 2035, the carbon storage of artificial forest will account for about 20% of the total carbon storage, of which the area of young-aged and middle-aged trees will account for 64.66% of the total area of trees in China, and it can be predicted that the carbon storage of main artificial arboreal forest will have great potential for increase.
【Objective】The carbon storage of a forest ecosystem in Wenzhou City, Zhejiang Province was studied to understand the current situation of forest ecosystem carbon storage and provide data for the evaluation of the regional carbon sink function.【Method】Based on monitoring data from the 10 main forest resource types in Pinus massoniana forest, other pine forest, Cunninghamia lanceolata forest, Cryptomeria japonica var. sinensis forest, Cupressus funebris forest, hardwood forest, mixed coniferous forest, mixed broadleaved forest, mixed coniferous and broadleaved forest, and Phyllostachys edulis forest in Wenzhou City in 2018, as well as the data measured from 30 survey sample plots, the carbon storage and carbon density were calculated for different forest types by using the average biomass conversion factor method. The Pearson correlation analysis method was used to analyze the correlation of organic carbon storage among the different forest ecosystem components.【Result】The carbon storage of the forest ecosystem in Wenzhou City was 81.70 Tg, including 18.46 Tg in the tree layer, 1.55 Tg in the shrub and grass layer, 1.02 Tg in the litter layer, and 60.67 Tg in the soil layer, accounting for 22.60%, 1.89%, 1.25%, and 74.26% of the carbon storage of the ecosystem, respectively. The carbon density of the forest ecosystem in Wenzhou was 123.81 t/hm2, including 27.98 t/hm2 in the tree layer, 2.34 t/hm2 in the shrub and grass layer, 1.54 t/hm2 in the litter layer, and 91.95 t/hm2 in the soil layer. The soil organic carbon pool was 2.88 times that of the vegetation organic carbon pool. The organic carbon storage of the tree layer and the soil layer represented the main carbon pool of the forest ecosystem, accounting for 96.86% of the total organic carbon storage. In the arbor layer, the highest carbon density was recorded in the cypress forest (46.06 t/hm2) and the lowest carbon density was in the broadleaved mixed forest (20.50 t/hm2). In the soil layer, the highest carbon density was the Cryptomeria japonica var. sinensis forest (136.97 t/hm2) and the lowest was the other pine forests (49.38 t/hm2). There were some differences in the carbon density of the stand ecosystem for different species. The Cryptomeria japonica var. sinensis forest had the highest carbon density (185.42 t/hm2) and the Pinus massoniana forest had the lowest carbon density (83.34 t/hm2). There was a significant correlation between the carbon storage of the tree layer and the litter layer (P < 0.05). There was a highly significant correlation between the carbon storage of the soil layer and the carbon storage of the forest ecosystem (P < 0.01). This indicated that the soil layer contributed the most to the carbon storage of the entire ecosystem. The correlation between other components did not reach a significant level.【Conclusion】The carbon density of the forest ecosystem in Wenzhou was slightly higher than the average level in Zhejiang Province, but was lower than the average level of China. Therefore, improving the forest carbon density through sustainable forest management will be the focus of carbon sequestration forestry in the future in Wenzhou.
【Objective】Natural arbor forest biomass carbon pool and its changes were estimated for Fujian Province based on inventory data for forest resources. Strategies for increasing carbon sinks have been put forward, which provided a theoretical basis for the improvement of the carbon sequestration capacity and the scientific management of natural forest.【Method】The carbon storage and the carbon density of the natural arbor forest in Fujian Province were estimated based on four sets of forest inventory data from 2003 to 2018 using the continuous biomass expansion factor method, combined with the carbon fraction and the root shoot ratio of the main forest types.【Result】Results showed that the natural arbor forest carbon storage in Fujian Province increased from 156.11 Tg in 2003 to 248.68 Tg in 2018, with an average annual growth rate of 3.15%. The carbon density increased from 47.30 Mg/hm2 in 2003 to 76.24 Mg/hm2 in 2018, with an average annual growth rate of 1.93 Mg/hm2. The carbon storage of the natural arbor forest was dominated by broad-leaved species including mixed coniferous and broadleaved forest. This accounted for more than 70% of the four forest inventory periods up to 86.47%. From 2003 to 2018, the area of young and middle-age natural arbor forest accounted for 58.78%-73.76%,and the carbon storage accounted for 50.72%-61.90%. The area and the carbon storage were predominantly young and middle-aged forest,but the proportion showed a pronounced downward trend. The proportion of carbon storage was significantly lower than that of the area. The carbon density of the natural arbor forest showed a pronounced upward trend with the increase in forest age. The carbon density of the broadleaved species was higher than that of the coniferous species.【Conclusion】The natural arbor forest carbon storage and the carbon density of Fujian Province show a trend of rapid growth, and the carbon sink capacity markedly enhanced. With the continuous strengthening of natural forest protection and ecological restoration, the dominant young and middle-age forest has entered a fast period for growth. There is considerable potential for natural arbor forest carbon sequestration in the future.
