油桐林生物量和养分循环的研究

对不同生育期的油桐林生物量和大量营养元素(N、P、K、Ca、Mg)的生物循环进行了研究。结果表明,桐林的生物量随树龄的增大逐渐积累,从幼龄期开始到20年生的桐林,其生物量的积累值为79,61t/ha。桐林不同生育期的光合产物在各器官中的分配比例不同。经济产量(果生物量或种仁生物量)随树龄的动态变化服从二次抛物线函数:W_(FR)=-2.11398+0.82471(t-1)-0.03540(t-1)~2W_S=-1.37257+0.38539t-0.01706t~2不同生育期,桐林中大量营养元素的吸收量、存留量、归还量和输出量均不同。     

Comparison of structural diversity of tree-crop associations in Peripheral and Buffer zones of Gachabari Sal forest area, Bangladesh

The structural diversity of different tree-crop associations were studied at Gachabari Sal forest area of Madhupur Garh on Buffer and Peripheral Zone during 2006. The total density, basal area of trees in the Buffer and Peripheral Zone were 155.5 trees·hm^-2, 795.4 trees·hm^-2 and 3.9 m^2·hm^-2, 5.8 m^2·hm^-2, respectively. No regeneration and natural trees were found in Peripheral Zone and the Zone is totally occupied by exotic species where the Buffer Zone comprised of both natural and exotic trees. The Peripheral Zone belonged to younger and smaller trees whereas the Buffer Zone belonged to mixture of smaller, taller, younger and mature trees simultaneously. For the practicing of different agroforestry systems both Zones have lost their original characters of Sal forest.     

紫花苜蓿蓄水保土功能与经济效益分析

研究了退耕还林地种植的一年生紫花苜蓿蓄水保土功能并进行了经济效益分析。结果表明：在退耕还林地上种植紫花苜蓿可显著改善土壤的物理性状，增加土壤孔隙度，减少土壤容重，防止水土流失.减少土壤侵蚀作用十分显著。其茎叶持水率可达自身重量的34.3％，其根系大部分分布在0～30cm土层内。生物量为5.892t/hm^2，年产干草30.0～37.5t/hm^2，直接经济效益达18000～22500元/hm^2。其生态效益与经济效益均十分显著。     

长白落叶松丰产林造林密度及其经济效益初探

本文以长白山落叶松人工林的造林初植密度为研究对象,在5种不同初植密度下,优选出适于黑龙江省利用世界银行贷款集约经营人工林项目合理密度。建筑材林分的合理初植密度为3000株/ha,纤维材林分为3300株/ha。     

浅析日本的森林公益机能经济价值评价

简要分析了日本全国水平的森林公益机能经济价值评价的历史和现状 ,并讨论了将来的发展趋势。日本人对森林公益机能的认识较早 ,频繁的自然灾害和林业经济的不景气是森林公益机能经济价值评价的起因和动机。从 1972年开始的全国森林公益机能的价值评价 ,当时用代替法 (RCM )评价出的金额约为 12 8兆日元 ;1987年单独评价东京圈内的森林价值的结果 ,每公顷森林测算出的价值为 5 0 0万日元 ,如按 5 %的还原率计算 ,其资本还原价高达每公顷 1亿日元。 2 0世纪 80年代还出现了用支付意愿法 (WTP)评价环境财产的事例。至 2 0 0 0年同样用 1972年使用过的代替法 (RCM )重新评价全国森林的结果 ,核算出约 75兆日元的最新数字。但至今为止评价过程中存在问题尚多 ,评价手法上也有局限性 ,其成果仅能为部分林业政策的制定和环境工程的评价起有限的参考作用。指出国际上森林公益机能价值评价今后的动向 ,提出了进一步开展评价理论和方法研究的必要性和重要性 ,并对中国林业可持续发展的启示提出了一些见解     

净现值法在林分经济成熟中的应用探讨

利用微观经济学手段,对林分生长过程进行了经济分析.根据林分经济成熟的内涵,结合林学知识,分析了净现值法在林分经济成熟中的应用.     

European forest accounting: general concepts and Austrian experiences

Within the European Union there exist three different frameworks for forest accounting at the national level. For purposes of the national accounts, the regulations of the European System of Integrated Economic Accounts (ESA) have to be observed. They require a distinction between forestry and logging and provide specific guidelines for the valuation of standing timber. In recognition of the special character of forests and forestry production, two satellite accounts are devoted to forestry: the Economic Accounts for Forestry (EAF) and the European Framework for Integrated Environmental and Economic Accounting for Forests (IEEAF). Although they were designed as complementary to the national accounts and refer to the same basic methodologies, the guidelines for forest accounting provided by the three manuals are not fully compatible. Just recently, a further integration and harmonization of the concepts for forest accounting has been proposed. Austria has implemented the valuation of the increment as an output of forestry as requested by ESA and produces the EAF tables on a regular basis. The possibilities for extending forest accounting to natural resource accounts for standing timber and the IEEAF have been investigated in terms of pilot studies. The Austrian experiences and results exemplify the problems and possible solutions associated with the adoption of the different European schemes. Data deficits and valuation issues restrict the significance of respective results to some degree, especially as regards forestry-specific extensions of the accounting schemes.     

国有林业产业对地区经济发展贡献度的动态演绎分析

基于1998~2018年黑龙江省国有林业产业数据,从发展规模、产业结构、投入产出效益、专业化水平等4个方面对黑龙江省国有林业产业发展现状进行总体概述和分析。借助产业贡献度指标测算国有林业产业对黑龙江省经济发展的贡献水平,并基于三次产业构成进一步对国有林业产业贡献度进行了结构性动态评价。研究得出:黑龙江省国有林业产业对地区经济发展贡献呈现稳步上升的特征,第一产业表现突出,第二、三产业呈小幅下降、小幅上升的反向变动特征。基于结果分析,从产业自身发展和持续推进多种经营产业转型两个方面提出方向性建议。     

小陇山林区日本落叶松人工商品林抚育间伐技术及经济效益研究

通过分析，确定了小陇山林区日本落叶松人工商品林抚育间伐的时间，抚育间隔期及抚育强度，预测了抚育间伐的经济效益。     

Effects of organic and mineral fertilizer inputs on maize yield and soil chemical properties in a maize cropping system in Meru South District, Kenya

Soil nutrient depletion as a result of continuous cultivation of soils without adequate addition of external inputs is a major challenge in the highlands of Kenya. An experiment was set up in Meru South District, Kenya in 2000 to investigate the effects of different soil-incorporated organic (manure, Tithonia diversifolia, Calliandra calothyrsus, Leucaena leucocephala) and mineral fertilizer inputs on maize yield, and soil chemical properties over seven seasons. On average, tithonia treatments (with or without half recommended rate of mineral fertilizer) gave the highest grain yield (5.5 and 5.4 Mg ha⁻¹ respectively) while the control treatment gave the lowest yield (1.5 Mg ha⁻¹). After 2 years of trial implementation, total soil carbon and nitrogen contents were improved with the application of organic residues, and manure in particular improved soil calcium content. Results of the economic analysis indicated that on average across the seven seasons, tithonia with half recommended rate of mineral fertilizer treatment recorded the highest net benefit (USD 787 ha⁻¹) while the control recorded the lowest (USD 272 ha⁻¹). However, returns to labor or benefit-cost ratios were in most cases not significantly improved when organic materials were used.