【摘要】 老龄林是重要的森林碳库,研究老龄林碳储量长期变化对评价老龄林碳源和碳汇功能和量化区域尺度森林生态系统碳循环具有重要的意义。基于云南省迪庆自治州森林资源规划设计调查数据、样地数据和迪庆州造林、采伐、灾害等统计数据,运用林业碳收支模型（CBM-CFS3）模拟并预测了2005—2020年云南省迪庆州区域尺度云杉（Picea likiangensis）老龄林（过熟林）的生物量、死亡有机质（包括枯落物、枯死木和土壤有机碳）以及生态系统碳储量及其动态变化。结果表明,干扰情景下,2005—2020年迪庆州云杉老龄林的生物量、死亡有机质和生态系统碳储量范围分别为3.98⁴.73 Tg、5.41⁷.28 Tg和9.44¹2.01 Tg,且均呈逐渐增长趋势。模拟期间,云杉老龄林的生物量碳密度和生态系统碳密度均呈减少趋势,其中生物量碳密度平均值为106.40 Mg·hm^-2,生态系统碳密度平均值为255.56 Mg·hm^-2;死亡有机质碳库碳密度呈增加趋势,平均值为149.16 Mg·hm^-2。研究结果显示,迪庆州云杉老龄林生态系统碳储量动态受林分生长、成熟林为过熟林和干扰三方面影响;其中自然生长导致生态系统碳储量增加0.51 Tg,成熟林进阶导致生态系统碳储量增加2.75 Tg,而采伐干扰造成生态系统碳储量损失1.14 Tg。建议未来森林经营中将老龄林每年采伐总面积控制在1.9×10³ hm2·a^-1以内,以保证老龄林生态系统碳储量趋于稳定,避免老龄林转变为碳源。更多还原

【Abstract】 Old-growth forest is an essential carbon pool in forest ecosystem.To understand the function of old forest as a carbon sink or source,it is necessary to quantify the long-term carbon dynamics in old-growth forest ecosystem on regional scale.Supported by local forest inventory data,field measurement data,statistics data on afforestation,reforestation,harvesting and disturbances（forest fire and other damages） from Diqing Tibetan Autonomous Prefecture,we used a forest carbon budget model（CBM-CFS3） to simulate and project the carbon dynamics affected by disturbance scenarios in the old-growth spruce（Picea likiangensis） forest in Diqing from 2005 to 2020.The results showed that the carbon stocks increased from 3.98 to 4.73 Tg（by C） in biomass,from 5.41 to 7.28 Tg in dead organic matter（DOM,which include litter,dead wood and soil organic carbon）,and from 9.44 to 12.01 Tg in total ecosystem from 2005 to 2020.The average carbon density in biomass and total ecosystem tended to decrease,which averaging as 106.40 Mg·hm^-2 and 255.56 Mg·hm^-2 during the period,respectively.But the carbon density in DOM,averaged as 149.16 Mg·hm^-2,tended to increase during the simulation period.Our simulation result also showed that carbon dynamics of old-growth spruce forest was obviously influenced by three factors: stand growth,mature-forest moved forward and harvesting disturbance.Positive effects including mature-forest moving forward（totally 2.75 Tg） and forest ageing（totally 0.51 Tg） increased the carbon stock of old-growth forest ecosystem.Harvesting,in contrast,had a negative effect and reduced carbon stock by 1.14 Tg during the period.If the disturbed area could be controlled as smaller than 1.9×103 hm²·a^-1 in the future forest management practices,it would effectively prevent the old-growth spruce forest ecosystem in Diqing from being a net carbon source.更多还原