碳汇木材复合经营对杉木人工林经济成熟龄及现值收益的影响

摘要

以中亚热带杉木中心产区为案例，基于样地调查数据、前人有关模型及相关经济技术指标，采用年均净现值法研究碳汇木材复合经营目标下杉木人工林经济成熟龄及现值收益，探讨了立地质量、木材及碳价格、森林经营成本、利率等因素变化对经济成熟龄及现值收益的影响.结果表明：在地位指数为16 m、利率为5％、碳价格为42.41元��t-1的条件下，杉木人工林经济成熟龄为19 a，年均碳汇木材复合收益最大值max( ANPVw＋c )为1695.5元��hm-2.回归分析发现，碳汇木材收益净现值NPVw＋c和ANPVw＋c与林龄之间分别呈现出Sigmoid函数、三次函数关系；增加碳汇目标并未对经济成熟龄产生影响，但现值收益max( ANPVw＋c )增加幅度为7.34％~9.96％；地位指数从8 m指数级增加到24 m指数级，经济成熟龄由25 a提前至16 a，max(ANPVw＋c)由225.3元��hm-2增加到5680.1元��hm-2；木材价格每上涨或降低5％，max(ANPVw＋c)上升或下降5.65％~9.97％；营林成本每上涨或降低5％，max(ANPVw＋c)下降或上涨2.01％~4.84％；经济成熟龄随利率水平的提高而不断提前，max(ANPVw＋c)则逐渐下降，利率每提高1％，max(ANPVw＋c)下降13.66％~20.04％；碳价格从0增加至800元��t-1，经济成熟龄提前1~3 a，max(ANPVw＋c)增加2.39~2.94倍，碳价格每提高一个价位，max(ANPVw＋c)平均增加11.55％~14.53％.表明增加碳汇经营目标对现值收益有较大影响，木材收益目标和碳汇收益目标可以兼容，为开展人工林碳汇经营、发挥人工林巨大的碳汇潜力以及增加林业经营者的收益等提供重要依据.%To evaluate uncertainty and risk on plantation investment, site quality, timber and carbon price, silviculture cost, impact of interest rate change on economic maturity age and present value of central area of Cunninghamia lanceolata plantation were inves-tigated basing on sample plot surveying and previous economic indexes. Average net present value method was applied to calculate e-conomic maturity age and present value. Results indicated that when exponential economic was 16m, interest rate P being 5% and carbon price Pc reaching 42. 41 yuan��t-2 , maturity age was 19 years, with average net present value max ( ANPVw+c ) reaching 1 695.5 yuan��hm-2 . According to regression analysis, net present value NPVw+c and ANPVw+c with forest age could be represented by Sigmoid and cubic function, respectively. Though carbon source did not influence economic maturity age, max( ANPVw+c ) in-creased by 7.34%-9.96%. When site index increased from 8 m to 24 m exponential, economic maturity age dropped from 16 a to 25 a, with max(ANPVw+c) increasing from 225.3 to 5 680.1 yuan��hm-2. Furthermore, when max (ANPVw+c) increased by 5.65%-9.97%,timber price and silviculture cost simultaneously rose by 5%, correspondingly, max( ANPVw+c ) dropped by 2.01%-4.84%, and vice versa. Economic maturity age was shortened and max( ANPVw+c ) was reduced when interest rate increased. To be specific, max( ANPVw+c ) dropped by 13.66%- 20.04% when interest rate increased by 1%. With Pc increasing from 0 to 800 yuan��t-1 , eco-nomic maturity age was cut down by 1 to 3 years and max( ANPVw+c ) increased by 2.39-2.94 times. In other word, max( ANPVw+c ) increased by 11.55%-14.53% with carbon price rose per 100 yuan��t-1 . To summarize, joint carbon and timber management has great impact on economic maturity age and present value. To fully play the role of plantation in carbon sequestration, integrated car-bon benefit and timber resource management should be taken into emphasis.