落叶松人工林间伐技术优化研究*

本文以林分生长模型为基础，将林分的经营指数作为状态变量，将主伐时林分平均直径作为目标，将达到这一目标时林分总收获蓄积量作为指标函数，建立了离散确定性动态规划模型，编制了计算机模拟系统。利用此系统即可对落叶松不同培育目标下的最佳间伐时间、间伐强度和主伐年龄等进行决策。结果表明，优化决策方法在保留株数、间伐次数和总收获蓄积量上都优于一般决策方法，它既可对落叶松林分进行生长预测，也可为制定经营单位的经营     

城市道路网信息管理系统研究

针对国内城市交通规划缺乏完整的道路信息资料 ,提出了如何利用功能完善的EMME/2交通规划软件结合中国的交通特性 ,进行城市路网信息资料的获取 ,并提出相应的数据库记录规定 ,据此研制开发了城市道路网信息管理系统。     

Cutting technic forPinus elliottii plantation of the multi-benefit management pattern

The cutting technic for thePinus elliottii plantation of the multi-benefit management pattern in the hilly region of Jiangxi Province was studied by establishing the model of growth progress according to Richards function and simulating the tending cutting on computer by use of dynamic programming. The results showed that the best time for the initial thinning was at tree age of 8–10 and final cutting was at tree age of 25. The optimal thinning project was 3 times of thinning cutting including the first thinning, and the thinning time was at tree ages of 8, 12 and 16, respectively. Their thinning intensities were separately 950, 700 and 300 trunks per hectare, and the preserved density was 550 trunks per hectare until the final cutting Foundation item: This study was supported by Natural Science Foundation of Jiangxi Province (A grant 0330023) Biography: WANG Qing-chun (1970-), male, Ph. Doctor, Senior Engineer in Academy of Forest Inventory & Planning, Jiangxi, Nanchang 330046, P.R. China. Responsible editor: Song Funan     

Improving adoptability of farm forestry in the Philippine uplands: a linear programming model

In the Philippines, smallholder farmers have become major timber producers. But the systems of timber production practiced have several limitations. In intercropping systems, the practice of severe branch and/or root pruning reduces tree-crop competition and increases annual crop yields, but is detrimental to tree growth and incompatible with commercial timber production. In even-aged woodlots, lack of regular income and poor tree growth, resulting from farmers’ reluctance to thin their plantations, are major constraints to adoption and profitable tree farming. In the municipality of Claveria, Misamis Oriental, the recent practice of planting trees on widely spaced (6–8 m) contour grass strips established for soil conservation suggests ways to improve the adoptability (i.e., profitability, feasibility and acceptability) of timber-based agroforestry systems. Assuming that financial benefits are the main objective of timber tree farmers, we develop a simple linear programming (LP) model for the optimal allocation of land to monocropping and tree intercropping that maximizes the net present value of an infinite number of rotations and satisfies farmers’ resource constraints and regular income requirements. The application of the LP model to an average farmer in Claveria showed that cumulative additions of widely spaced tree hedgerows provides higher returns to land, and reduce the risk of agroforestry adoption by spreading over the years labour and capital investment costs and the economic benefits accruing to farmers from trees. Therefore, incremental planting of widely spaced tree hedgerows can make farm forestry more adoptable and thus benefit a larger number of resource-constrained farmers in their evolution towards more diverse and productive agroforestry systems.     

A Danish example of optimal thinning strategies in mixed-species forest under changing growth conditions caused by climate change

In this study, we analyse the economic and managerial aspects of option values related to having a mixed-species stand. As an example, we look at a mixed Norway spruce and Sitka spruce stand in Denmark when timing and intensity of future climate, and its effect on tree growth, are uncertain. Assuming that tree growth follows a discrete non-stationary stochastic process, we use dynamic programming to optimise the harvest distribution between the two species.

The results show that facing growth uncertainty caused by potential climate change implies an option value. Such uncertainty can be a potential advantage as long as we are able to maintain flexibility, keep decisions open, and there is a chance that climatic change will benefit some species. We analyse the model under different uncertainty assumptions and show that the larger changes we expect, the higher is the option value at any time during the stand’s life and, hence, we keep, on average, both tree species in the stand for a longer period of time. Moreover, we find that the adjustments may take place rather late in the rotation, a result brought about by the significance of the option value, which makes it optimal to maintain a reasonable stocking of both species.     

河南省林种结构调整的研究

根据１９９３年省森林资源清查、森林资源消耗量及消耗结构的调查资料，以可持续发展的理论为指导，采用线性规划对我省的林种结构进行了研究。研究结果：河南省现阶段的林种结构应为：用材林∶防护林∶经济林∶薪炭林∶特用林＝３４９∶１５９∶２３７∶２１１∶４４。     

山西石楼县生态林业工程建设中的土地合理利用

根据区域生态经济学原理 ,结合晋西石楼县生态林业工程建设的实践 ,分析了县域土地资源利用现状 ,进行了土地利用多目标综合规划 ,阐述了生态林业工程土地合理利用的途径 ,并对其战略决策进行了分析。     

基于激光雷达数据的东北林区航空林分材积表编制

利用东北林区云冷杉林、落叶松林、樟子松林、红松林、栎树林、桦树林、杨树林、榆树林、椴树林和水胡黄林10种森林类型的1947个样地的激光雷达数据和地面实测蓄积量数据,首先通过多元线性回归和非线性回归方法,分别建立基于机载激光雷达数据的森林蓄积量回归估计模型,并通过对比分析,确定统一形式的基础回归模型;然后利用哑变量建模方法,建立基于不同森林类型参数和相同激光雷达变量的蓄积量模型。结果表明,研究建立的10种森林类型的线性蓄积量回归模型的解释变量个数在2~7之间,确定系数在0.460~0.858之间;非线性蓄积量回归模型的解释变量个数在2~4之间,确定系数在0.461~0.846之间。基于点云平均高度和平均强度建立的10种森林类型的二元蓄积量模型(研究称之为标准模型),其确定系数在0.440~0.815之间,平均预估误差在2.88%~4.42%之间,平均百分标准误差在16.76%~25.52%之间,预估精度基本达到森林资源规划设计调查技术规定要求。依据研究建立的10种森林类型的蓄积量模型,可以编制基于激光雷达数据的航空林分材积表,在森林资源调查实践中推广应用。     

Strategies of inorganic and organic trace mineral supplementation in gestating hyperprolific sow diets: effects on the offspring performance and fetal programming

The aim of the present study was to evaluate the effect of trace mineral nutrition on sow performance, mineral content, and intestinal gene expression of neonate piglets when inorganic mineral sources (ITM) were partially replaced by their organic mineral (OTM) counterparts. At 35 d postmating, under commercial conditions, a total of 240 hyperprolific multiparous sows were allocated into three experimental diets: 1) ITM: with Zn, Cu, and Mn at 80, 15, and 60 mg/kg, respectively; 2) partial replacement trace mineral source (Replace): with a 30 % replacement of ITM by OTM, resulting in ITM + OTM supplementation of Zn (56 + 24 mg/kg), Cu (10.5 + 4.5 mg/kg), and Mn (42 + 18 mg/kg); and 3) Reduce and replace mineral source (R&R): reducing a 50% of the ITM source of Zn (40 + 24 mg/kg), Cu (7.5 + 4.5 mg/kg), and Mn (30 + 18 mg/kg). At farrowing, 40 piglets were selected, based on birth weight (light: <800 g, and average: >1,200 g), for sampling. Since the present study aimed to reflect results under commercial conditions, it was difficult to get an equal parity number between the experimental diets. Overall, no differences between experimental diets on sow reproductive performance were observed. Light piglets had a lower mineral content (P < 0.05) and a downregulation of several genes (P < 0.10) involved in physiological functions compared with their average littermates. Neonate piglets born from Replace sows had an upregulation of genes involved in functions like immunity and gut barrier, compared with those born from ITM sows (P < 0.10), particularly in light piglets. In conclusion, the partial replacement of ITM by their OTM counterparts represents an alternative to the totally inorganic supplementation with improvements on neonate piglet gene expression, particularly in the smallest piglets of the litter. The lower trace mineral storage together with the greater downregulation of gut health genes exposed the immaturity and vulnerability of small piglets.     

Low protein provision during the first year of life,but not during foetal life,affects metabolic traits,organ mass development and growth in male mink (Neovison vison)

Low protein provision in utero and post‐partum may induce metabolic disorders in adulthood. Studies in mink have mainly focused on short‐term consequences of low protein provision in utero whereas the long‐term responses to low protein (LP) provision in metabolically programmed mink are unknown. We investigated whether low protein provision in utero affects the long‐term response to adequate (AP) or LP provision after weaning in male mink. Eighty‐six male mink were exposed to low (19% of ME from CP; crude protein) or adequate (31% of ME from CP) protein provision in utero, and to LP (~20% of ME from CP) or AP (30–42% of ME from CP) provision post‐weaning. Being metabolically programmed by low protein provision in utero did not affect the response to post‐weaning diets. Dietary protein content in the LP feed after weaning was below requirements; evidenced by lower nitrogen retention (p < 0.001) preventing LP mink from attaining their growth potential (p < 0.02). LP mink had a lower liver, pancreas and kidney weight (p < 0.05) as well as lower plasma IGF‐1 concentrations at 8 and 25 (p < 0.05) weeks, and a higher incidence of hepatic lipidosis at 25 weeks (p < 0.05). Furthermore, LP mink had a higher body fat (p < 0.05) and lower body CP content (p < 0.05) at 50 weeks of age. It is concluded that some effects of low protein provision in utero can be alleviated by an adequate nutrient supply post‐partum. However, long‐term exposure to low protein provision in mink reduces their growth potential and induces transient hepatic lipidosis and modified body composition.