基于碳汇木材复合经营目标的综合效益及影响因素分析

【目的】研究基于碳汇木材复合经营目标的最优森林管理,为提高森林综合效益提供理论依据。【方法】基于福建顺昌国有林场杉木和桉树经营成本数据,结合生长收获模型和碳储量模型,利用修正的Faustmann-Hartman模型,以社会效用最大的综合效益为决策目标,模拟分析营林成本、碳价格、木材价格和利率变动对杉木、桉树多效益经营下综合效益的影响。【结果】在当前营林成本和经营强度不变的情况下,多效益经营提升了综合效益,说明碳汇经营具有一定的投资效益。在营林成本变动(-40%~40%)范围内,随着营林成本的增加,杉木综合效益从40 402.33元/hm²下降到5 599.02元/hm²,桉树综合效益由51 521.61元/hm²下降到15 530.34元/hm²,两树种轮伐期均延长2 a。碳价格由0上升到500元/t时,杉木综合效益由21 423.52元/hm²上升到34 209.48元/hm²,最优轮伐期均为20 a;桉树综合效益从25 845.13元/hm²上升到92 644.11元/hm²,最优轮伐期由8 a下降至6 a。在木材价格变动(-20%~20%)范围内,随着木材价格的增加,杉木综合效益由4 545.44 元/hm²上升到41 117.14元/hm²,最优轮伐期缩短1 a;桉树综合效益由9 575.92元/hm²上升到56 470.14元/hm²,最优轮伐期缩短3 a;利率从1%上升到7%时,杉木综合效益由383 745.32元/hm²下降到890.14元/hm²,最优轮伐期缩短6 a;桉树综合效益由254 648.72元/hm²下降到16 728.99元/hm²,最优轮伐期缩短1 a。【结论】杉木、桉树的综合效益受碳价格和木材价格正向调节,受利率和营林成本的负向调节;杉木、桉树的综合效益对不同经济因素敏感性大小和顺序不同;在森林综合效益方面,桉树大于杉木,而在应对气候变化方面,杉木响应优于桉树。

Analysis of comprehensive benefits and influencing factors based on the combined economic value of carbon sequestration and timber benefits

【Objective】This study aimed to explore the optimal forest management for combined carbon sequestration benefits and timber values and provide a theoretical basis for improving the comprehensive benefits of forests.【Method】Based on the forest management cost data and harvest carbon model of Chinese fir and eucalyptus in the Shunchang County State-owned Forest Farm of Fujian Province, a modified Faustmann-Hartman model was used to predict the effects of forest management costs, carbon sequestration benefits, timber value, and interest rate fluctuation on optimal forest economic value.【Result】Under the existing conditions of constant forest management cost and management intensity, multiple-benefit management involving carbon sequestration may improve the optimal forest economic value, suggesting that the carbon market has certain investment benefits. If the silvicultural cost fluctuates from-40% to 40%, the comprehensive benefits of Chinese fir and eucalyptus will decrease from 40 402.33 to 5 599.02 yuan/hm² and 51 521.61 to 15 530.34 yuan/hm², respectively, and the rotation period of the two tree species will extend for two years. When the timber price increases from null to 500 yuan/hm², the comprehensive benefits of Chinese fir and eucalyptus will increase from 21 423.52 to 34 209.48 yuan/hm² and 25 845.13 to 92 644.11 yuan/hm², respectively. The optimal rotation period of Chinese fir will remain at 20 years;however, that of eucalyptus will decrease from 8 years to 6 years, being associated with rising timber prices. When the interest rate increases from 1% to 7%, the comprehensive benefit of Chinese fir will decrease from 383 745.32 to 890.14 yuan/hm², and its optimal rotation period will be shortened by 6 years. With the same interest rate change, the comprehensive benefits of eucalyptus will decrease from 254 648.72 to 16 728.99 yuan/hm², and its optimal rotation period will be shortened by one year. 【Conclusion】Carbon sequestration benefits and timber prices positively affect the comprehensive benefits of Chinese fir and eucalyptus, whereas interest rate and silvicultural cost have a negative impact. The sensitivity and order of the comprehensive benefits of Chinese fir and eucalyptus to the various economic factors differ;in terms of forest comprehensive benefits, eucalyptus is better than Chinese fir;however, the reverse is true in response to climate change.