摘要： 樟子松(Pinus sylvestris var. mongolica)作为华北地区重要的造林树种, 其生长及固碳特征的研究对樟子松人工林经营有着重要的意义。该文通过2006-2016年10年的定点观测, 研究河北省塞罕坝林场樟子松人工林的生长和固碳特征。结果表明: 10年间樟子松人工林胸径年增长4.19%, 树高年增长1.97%; 林木死亡率8.39%。该林分2006年和2016年的碳储量分别为59.04和109.64 t?hm-2, 即10年间固碳量为50.6 t?hm-2, 固碳年平均增长8.57%。不同径级的林木固碳能力有差异, 0-10 cm径级的林木总株数占39.1%, 但固碳量仅占8.3%; 10-20 cm径级的林木株数占59.2%, 固碳量占比达87.1%。结果显示樟子松人工林具有较大的固碳潜力, 未来评估林分生态效益与固碳潜力时, 应充分考虑林分的结构特征。
樟子松(Pinus sylvestris var. mongolica)作为华北地区重要的造林树种, 其生长及固碳特征的研究对樟子松人工林经营有着重要的意义。该文通过2006-2016年10年的定点观测, 研究河北省塞罕坝林场樟子松人工林的生长和固碳特征。结果表明: 10年间樟子松人工林胸径年增长4.19%, 树高年增长1.97%; 林木死亡率8.39%。该林分2006年和2016年的碳储量分别为59.04和109.64 t?hm-2, 即10年间固碳量为50.6 t?hm-2, 固碳年平均增长8.57%。不同径级的林木固碳能力有差异, 0-10 cm径级的林木总株数占39.1%, 但固碳量仅占8.3%; 10-20 cm径级的林木株数占59.2%, 固碳量占比达87.1%。结果显示樟子松人工林具有较大的固碳潜力, 未来评估林分生态效益与固碳潜力时, 应充分考虑林分的结构特征。
Abstract: Aims Pinus sylvestris var. mongolica is one of the main afforestation tree species in North China. It is important to study the characters of growth and carbon (C) sequestration, which can provide scientific basis for the sustainable management. Therefore, our study aims at quantifying the growth characters and C sequestration in these middle-aged plantations, and to investigate the effect of diameter at breast height (DBH) on those dynamics. Methods We selected a middle-aged P. sylvestris var. mongolica plantation as our permanent experimental plot, which is located in Saihanba, Hebei Province, China. DBH and height of all stands in this plot were measured in 2006 and 2016. Based on the anatomical trees and allometric equation, we calculated C density and sequestration from 2006 to 2016. We also analyzed C sequestration in different DBH groups in the study area. Important findings Our results showed that the carbon sink of those middle-age (age between 28 and 38 years old) plantation would be enhanced in future, and there were differences in characters of growth and C sequestration among DBH groups. The decadal increment rate of DBH and height were 4.19% and 1.97%, and the increment rate was the lowest in the 0-10 cm DBH class. The mortality rate of the plantation was 8.39%, with 7.82% mortality occurred in 0-10 cm tree size class. The forest stands biomass carbon stocks in 2006 and 2016 were 59.04 and 109.64 t?hm-2, respectively, and almost 87.1% of the carbon stocks were in the middle DBH-class, even though the number of trees only accounted for nearly 59.2%. The small class’s number of trees accounted for 39.1%, while the carbon stocks accounted for 8.3%. Our results also demonstrate that forests in Saihanba would continue to act as a carbon sink in the coming years. The variations among DBH groups highlights that the diameter class should be taken into consideration while assess the ecological efficiency and carbon sequestration capacity in a certain area.
Aims Pinus sylvestris var. mongolica is one of the main afforestation tree species in North China. It is important to study the characters of growth and carbon (C) sequestration, which can provide scientific basis for the sustainable management. Therefore, our study aims at quantifying the growth characters and C sequestration in these middle-aged plantations, and to investigate the effect of diameter at breast height (DBH) on those dynamics. Methods We selected a middle-aged P. sylvestris var. mongolica plantation as our permanent experimental plot, which is located in Saihanba, Hebei Province, China. DBH and height of all stands in this plot were measured in 2006 and 2016. Based on the anatomical trees and allometric equation, we calculated C density and sequestration from 2006 to 2016. We also analyzed C sequestration in different DBH groups in the study area. Important findings Our results showed that the carbon sink of those middle-age (age between 28 and 38 years old) plantation would be enhanced in future, and there were differences in characters of growth and C sequestration among DBH groups. The decadal increment rate of DBH and height were 4.19% and 1.97%, and the increment rate was the lowest in the 0-10 cm DBH class. The mortality rate of the plantation was 8.39%, with 7.82% mortality occurred in 0-10 cm tree size class. The forest stands biomass carbon stocks in 2006 and 2016 were 59.04 and 109.64 t?hm-2, respectively, and almost 87.1% of the carbon stocks were in the middle DBH-class, even though the number of trees only accounted for nearly 59.2%. The small class’s number of trees accounted for 39.1%, while the carbon stocks accounted for 8.3%. Our results also demonstrate that forests in Saihanba would continue to act as a carbon sink in the coming years. The variations among DBH groups highlights that the diameter class should be taken into consideration while assess the ecological efficiency and carbon sequestration capacity in a certain area.
表1 樟子松和落叶松各生物量组分计算公式
Table 1 Formulae for biomass in different components of Pinus sylvestris var. mongolica and Larix principis-rupprechtii
表2 樟子松人工林林分结构特征(平均值±标准偏差)
Table 2 Stand characteristics of Pinus sylvestris var. mongolica plantations (mean ± SD)
表3 树木年生长量特征
Table 3 Dynamics of annual tree growth
图1 10年间塞罕坝樟子松人工林胸径、树高增长量(平均值±标准误差)。
Fig. 1 Decadal increment of diameter at breast height (DBH) and tree height in Pinus sylvestris var. mongolica plantations in Saihanba (mean ± SE).
图2 10年间不同径级的胸径、树高和胸高断面积增长量。小写字母表示不同径级的10年间胸径、树高、胸高断面积增长量的多重比较显著水平(p < 0.05) (平均值±标准误差)。
Fig. 2 Decadal increment of diameter at breast height (DBH), tree height and basal area in different DBH-class. Lowercase letter represent the significant level of multiple comparisons of decadal increment of DBH, tree height and basal area in different DBH-class (mean ± SE).
表4 不同径级林木死亡率
Table 4 Mortality of forest stand in different DBH-class
图3 2006年和2016年樟子松人工林胸径频率分布。
Fig. 3 Diameter at breast height (DBH) frequency distribution in Pinus sylvestris var. mongolica plantation in 2006 and 2016.
图4 10年间不同径级林木碳储量变化和碳储量年平均变 化率。
Fig. 4 Decadal variation and annual rate of change of tree carbon storage in different DBH-class. DBH, diameter at breast height.