单叶省藤与石梓间种的经济效益分析

评价了13a经营期内5种采收方式下单叶省藤人工林的经济效益,分析了间种对上层林木生长收获的影响以及对林地经济收益贡献水平。研究结果表明:不同的初采年龄和采收间隔期对13a单叶省藤人工林经济效益具有重要的影响,其中单叶省藤以9a初采和4a间隔期的采收方式获得最高经济效益,净现值、内部收益率和收益成本比分别为20255元·hm-2、20 08%、1 38;单叶省藤种植后对上层林木石梓的生长与收获量产生不利影响,进而导致20年生石梓林分的纯收益和净现值比未间种时分别减少4000、1500元·hm-2。通过综合分析,5种采收方式对整个林地经济收益仍有较大贡献,林藤间种产生的林地增益水平和净现值增量分别为12 49%～91 10%、706～5145元·hm-2。

An Economic Analysis of the Interplanting of Calamus simplicifolius with Gmelina arborea Plantation

The objective of this study was to analyze the economic benefit of rattan plantation and to determine the impact of harvesting regimes and management technique on economic return in the forestland.Data were obtained from the permanent plots established in Calamus simplicifolius plantation where 5 different harvesting regimes were set,including first harvesting at 5,6,7,8,9 years and harvesting intervals of 8,7,6,5,4 years respectively.In addition,field investigation on the upper support trees,20-year-old Gmelina arborea mixed with C.simplicifolius was made and 2 temporary plots nearby were also established in pure stands to know the effect of rattan planting on the growth and yield of support trees.Harvesting regimes had eminent effect on economics of 13-year-old rattan plantation.Under the regime of first harvesting at 9 years with 4 years'interval afterward,optimal economic benefit was gained in C.simplicifolius plantation,being 20 255 yuan·hm^-2,20.08%,1.38 in term of net present value (NPV),internal return rate (IRR) and the ratio of benefit to cost (B/C).Rattans had unfavorable effect on the growth and yield of upper trees.As a result,the net income and NPV from G.arborea plantation interplanted with C.simplicifolius decreased by 4 000 yuan·hm^-2 and 1 500 yuan·hm^-2 respectively over those from pure stand.However,the economic loss in the upper stand could be compensated with the monetary gain from rattan plantation generating considerable economic benefit.The level of economic gain and the increment of NPV by interplanting G.arborea with C.simplicifolius under various harvesting regimes were estimated to range from 12.49% to 91.10% and 706 yuan·hm^-2 to 5 145 yuan·hm^-2.