Abstract:

Quercus is the largest tree species in China with a great potential for carbon sequestration. This study examined the carbon stock and distribution pattern of the natural secondary Quercus mongolica forest under different management modes to provide theoretical bases for evaluating its carbon sink potential in China. To this end, the study employed the random layout and typical sampling method and collected both plant and soil samples for forest ecosystem carbon stock evaluation under three distinctive Q. mongolica forest stands with different management intensities within the Danqinghe Forest Station in Harbin, Heilongjiang province, northeast of China. These three Q. mongolica forest stands were (1) target tree nurture management (40%, 45% and 70% of nurture intensity), (2) comprehensive tree nurture management (45% and 40% of nurture intensity), and (3) undisturbed tree nurture management. The results showed that after 17 years of management practices, the carbon stock of secondary Q. mongolica forest under the undisturbed tree nurture management (279.01 t∙hm^-2) was significantly higher (P<0.05) than that under the other two tree nurture management modes, while the differences between comprehensive tree nurture (218.81 t∙hm^-2) and target tree nurture (183.01 t∙hm^-2) were not significant. The soil layer accounted for the largest share of the stand carbon stock (82.71%-89.56%), followed by the tree layer (9.53%-16.41%), the shrub layer, the herb layer, and the litter layer. The latter three combined only accounted for 1%. Carbon stock of the tree layer varied significantly (P<0.05) among the three management modes. The order of the carbon stock size was: no-disturbance tree nurture (45.78 t∙hm^-2)>comprehensive tree nurture (27.17 t∙hm^-2)>target tree nurture (17.44 t∙hm^-2) (P<0.05). The carbon stock of the shrub layer was significantly larger than that of target tree nurture under comprehensive tree nurture (P<0.05), and the carbon stock of the litter layer was significantly larger than that of comprehensive tree nurture and target tree nurture under no-disturbance tree nurture (P<0.05), while no differences were observed among these three management modes for the herb layer carbon stock. Soil carbon stock under no-disturbance management was significantly higher than that under target tree nurture (P<0.05), but similar with that under comprehensive tree nurture. In conclusion, from the perspective of enhancing the carbon sequestration potential and sustainable management, it is therefore recommended to reduce the management intensity of similar forest stands and optimize management technology measures to achieve multi-objective management of carbon sequestration and improve the quality of forest stands.

Key words: natural secondary Quercus mongolica forests, target tree forest management, comprehensive nurturing management, carbon stock, management mode, carbon sequestration potential

摘要：

栎类是中国第一大树种,固碳潜力巨大。以黑龙江省哈尔滨市丹清河实验林场蒙古栎（Quercus mongolica）天然次生林为研究对象,研究了目标树经营（经营强度45%、40%、70%）、综合抚育经营（经营强度45%、40%）、无干扰经营对林分碳储量及其分布的影响,为评估蒙古栎天然次生林的碳汇潜力提供理论依据。结果表明,（1）经过17年的经营实践,无干扰模式下蒙古栎天然次生林林分碳储量（279.01 t∙hm^-2）显著（P<0.05）高于目标树经营（183.01 t∙hm^-2）和综合抚育经营（218.81 t∙hm^-2）,但后两者之间差异不显著。（2）土壤层碳储量占林分碳储量的比重最大（82.71%—89.56%）,乔木层次之（9.53%—16.41%）,灌木层、草本层和凋落物层合计占1%左右。（3）乔木层碳储量在3种经营模式之间差异显著（P<0.05）,碳储量大小顺序为无干扰经营 (45.78 t∙hm^-2)>综合抚育经营 (27.17 t∙hm^-2)>目标树经营 (17.44 t∙hm^-2)。（4）灌木层碳储量在综合抚育经营下显著大于目标树经营（P<0.05）,凋落物层碳储量在无干扰经营下显著大于综合抚育经营和目标树经营（P<0.05）,草本层碳储量在3种经营模式之间无显著差异。（5）土壤层碳储量在无干扰经营模式下显著大于目标树经营（P<0.05）,但与综合抚育经营差异不显著。从提升林分固碳潜力和可持续经营的角度,建议对类似林分降低经营强度,优化经营技术措施,达到固碳增汇和提高林分质量的多目标经营。

关键词: 蒙古栎天然次生林, 目标树经营, 综合抚育经营, 碳储量, 经营模式, 固碳潜力