不同轮伐期对巨尾桉人工林碳固存的影响

【目的】深入探讨不同轮伐期对巨尾桉人工林碳固存的影响,为从应对全球气候变化的视角确定合理轮伐期提供理论依据。【方法】以轮伐期为短(7a)、中(13a)和长周期(21a)的巨尾桉人工林为研究对象,通过对不同轮伐期桉树林分生物量、碳固存、年平均固碳量的分析,揭示不同轮伐期对桉树林分碳固存的影响。【结果】巨尾桉人工林的生物量碳随着轮伐期的延长而逐渐增加,由7a轮伐期的(75.81±5.12)t·C/hm~2增至13a轮伐期的(180.11±19.97)t·C/hm~2以及21a轮伐期的(192.08±16.50)t·C/hm~2,方差分析表明,13a和21a轮伐期的总生物量碳显著高于7a轮伐期,而13a和21a轮伐期之间的差异不显著。巨尾桉人工林土壤有机碳随轮伐期延长而显著降低,由7a轮伐期的(89.99±0.35)t·C/hm~2、13a轮伐期的(85.42±0.76)t·C/hm~2下降到21a轮伐期的(74.64±0.24)t·C/hm~2。7~13a仍是巨尾桉人工林固碳能力迅速增长期,年平均总生物量碳由7a时的10.78t·C/(hm~2·a)迅速提高到13a的19.54t·C/(hm~2·a),增长81%;21a时巨尾桉人工林进入固碳能力下降期,年平均总生物量碳降至3.78t·C/(hm~2·a),固碳能力只是13a的19.34%。【结论】在南亚热带,巨尾桉人工林的最佳轮伐期确定在13a左右较为适宜,这与经济效益的最大化一致。

Effects of Rotation Length on Carbon Sequestration in Eucalyptus grandis×E.urophylla Plantations

Objective] The objective of this in-depth study was to provide theoretical foundation for confirming rational rotation length from the perspective of coping with global climate changes by investigating the effects of rotation length on carbon sequestration in Eucalyptus grandis×E.urophylla plantations.Methods] The short-term (7 a), medium (13 a), and long (21 a) rotations of Eucalyptus grandis×E.urophylla plantations were studied.Through the analysis of biomass, carbon sequestration, and annual average carbon sequestration of E.grandis×E.urophylla plantations in different rotations, the effects of different rotations on carbon sequestration of E.grandis×E.urophylla plantations were revealed.Results] With the extension of the rotation period, the biomass carbon sequestration of E.grandis×E.urophylla plantations sustainably increased.The biomass carbon sequestration increased from (75.81±5.12) t·C/hm² in 7 a to (180.11±19.97) t·C/hm² in 13 a, and slightly increased to (192.08±16.50) t·C/hm² in 21 a.Results of ANOVA showed that the total biomass carbon sequestration of the 13 a and 21 a rotations were significantly higher than the 7 a rotation, while the difference between the 13 a and 21 a rotations was not significant.The soil organic carbon sequestration in the Eucalyptus grandis×E.urophylla plantations decreased significantly with the extension of the rotation period.The soil organic carbon sequestration decreased from (89.99±0.35) t·C/hm² in 7 a and (85.42±0.76) t·C/hm² in 13 a to (74.64±0.24) t·C/hm² in 21 a.7~13 a was still a period of rapid growth of carbon sequestration capacity of Eucalyptus grandis×E.urophylla plantations, and the annual average total biomass carbon rapidly increased from 10.78 t·C/(hm²·a) in 7 a to 19.54 t·C/(hm²·a) in 13 a, which increased 81%.In 21 a, the Eucalyptus grandis×E.urophylla plantations entered a period of decline in carbon sequestration capacity, the annual average total biomass carbon fell to 3.78 t·C/(hm²·a), and the carbon sequestration capacity was only 19.34% of 13 a.Conclusion] In the South Asian subtropics, the rotation period of the Eucalyptus grandis×E.urophylla plantations was determined to be appropriate around 13 years, This was accordance with the maximum of economic benefits.