The method for designing the profile of forest roads supported by genetic algorithm

This study examines a method for designing an optimum profile of a forest road in a short matter of time. In this method, a genetic algorithm (GA) searches for points where the gradient changes and dynamic programing (DP) designs the longitudinal slope. This method can be applied to the ground heights of an actual forest road. The evaluation function of the DP assesses the total expenditure. The inverse of this function is the fitness function. Crossover and mutation are operators of an evolution simulation of a GA. They are each repeated 20 times and 420 profiles are designed and assessed, all within about 10 min. A comparison of the profile designed by the GA with that of an actual forest road shows only one section where the formation level differed substantially. Overall, both profiles seem to show a high degree of correspondence. From this result, we believe that the profile designed by the GA is best, or the one of the best. A conventional method takes about 65 h to calculate all changing points of gradients. However, by using the GA, the calculation time was reduced to about 1/389 that of the coventional method, showing that the method which uses the GA through the profile design is very useful.     

洞庭湖区防浪林林分林冠结构的研究

对洞庭湖区河洲、滩地上的不同林龄的旱柳、杨树防浪林、芦苇林进行了标准地调查,选取标准株(地),对其茎杆、枝条、叶片的空间分布进行了测定,通过对其差异进行比较分析,旨在间接测定不同防浪林的防浪效益的差异。     

浙江富阳市竹林道建设实践与问题探讨

基于富阳市竹林道建设7年多的实践,评估了竹林道建设的成本与效益,分析了目前竹林道建设中存在的问题,提出了加快竹林道建设的建议,即加大政府扶持力度、建立长效管理机制、深化林权体制改革、加强多部门协调合作等。     

The behaviour of the measure of surround in relation to the diameter and spatial structure of a forest stand

Forestry inventory practices have, in the past, concentrated on obtaining information primarily required for timber management. To assess the ecological impact of exploitation, particularly under continuous cover forest management, diversity measures are required that consider the structural diversity in a forest stand. The measure of surround that was initially developed in Germany may be used to quantify the spatial interspersion of different tree size classes as a measure of spatial diversity. While the measure of surround has been applied to practical problems in the past, little is known about its actual performance in relation to stand compositions. This study investigate the behaviour of the index using a number of simulated age class distributions under various degrees of interspersion to provide a norm against which it may be compared. The measure of surround applied to diameter distributions is closely related to the diameter structure of a stand. When diameter classes are interspersed completely randomly within a stand the relative cumulative frequency of the diameter class provides an estimator of the size specific measure of surround. This provides a baseline from which the index may be interpreted.     

易门县森林生态效益补偿中存在的问题及对策思考

国家建立森林生态效益补偿基金制度后,易门县列为森林生态效益补偿项目县之一,先后纳入中央财政和省级财政森林生态效益补偿面积71126．67hm^2。针对项目实施以来补偿中存在的问题进行了分析,提出了相应对策、建议。     

塞罕坝林场森林经营示范体系建设与发展构想

以全国首批森林经营示范国有林场之一的塞罕坝林场为研究对象,在总结以往生产管理经验的基础上,分析研究林场在生产中出现的主要问题,以及制约发展的主要因素,结合林场发展方向,对森林经营示范体系建设与发展构想进行了探讨。     

吉林省长白山林区采育林经营技术规程的研究

本文根据长白山顶级森林群落特点及林区现状,以现代林业理论为指导,以吉林省汪清林业局采育林模式为支撑,以林区大量森林调查数据为基础,提出了吉林省长白山采育林经营技术规程编制原则、内容及论据等,旨在用于指导吉林省长白山林区的森林经营。     

Topography related spatial distribution of dominant tree species in a tropical seasonal rain forest in China

The degree to which variation in species distribution is predictable from topographic variation is of considerable current interest. In this paper, canonical correspondence analysis (CCA), linear regression and principal coordinates of neighbour matrices (PCNM) models were used to explain the variation in the distributions of the 13 dominant species in a 20-ha tropical rain-forest plot in China. The results showed that: (1) Tree distribution maps show that some species are mainly found in the gullies of the plot, whereas others occur on the slopes. Which indicates topographic variables are important factors for the distribution pattern of species. (2) Both linear regression and CCA results show that convexity and elevation are the most important variables effecting distribution of trees. For saplings, elevation, convexity and aspect explain 15.3%, 9.0% and 10.1% of the total variation of species abundance. For poles, elevation and convexity explain 19.3% and 11.4% respectively. However, only 5.3% of the total variation is explained for adults. (3) The PCNM results showed that topography alone explained 20%, 24% and 5% of the total variation of species abundance for saplings, poles and adults, respectively. Overall evidence for topographic control of the tropical tree distribution is strong, but the explanatory power of topographic variables was a small part of the total of variation.     

安徽省石台县长江防护林工程建设现状研究

系统研究了石台县2001年~2007年长江防护林工程建设情况,特别是其4个主要工程类别:人工造林、低产林改造、幼林抚育和封山育林工程的建设规模和资金投入结构。在此基础上,结合该县长防林工程建设的成功经验、取得的三大效益及尚存在的主要问题,作者建议在今后的长防林建设工程中应该加强工程管理、增加国家投资、拓宽融资渠道、巩固基层林站和加强监督监测等。     

Population structure of Carapa guianensis in two forest types in the southwestern Brazilian Amazon

Carapa guianensis Aublet. is a tropical tree with strong multiple-use characteristics, and is valued for both the high quality oil extracted from its seeds and as a timber resource. This study compares the population structure of this economically important rainforest tree in two contrasting forest types: occasionally inundated and terra firme forests. Main study objectives were (a) to assess the density, spatial distribution, and size class structure of C. guianensis in these two forest types and (b) to use patterns of abundance, distribution and demographic structure to help infer key demographic stages or ecological variables that merit special focus for management. Four 400 m × 400 m plots, two in each forest type, were established to determine distribution and density patterns of C. guianensis ≥10 cm diameter at breast height (dbh) at the landscape level, and 32 10 m × 10 m subplots were randomly nested within each of the larger plots to measure individuals <10 cm dbh. Larger individuals (≥10 cm dbh) were found at higher densities in occasionally inundated forest than in terra firme forest: 25.7 trees ha⁻¹ and 14.6 trees ha⁻¹, respectively. Mean density of C. guianensis individuals <10 cm dbh was also higher in occasionally inundated forests, but variation of regeneration density among the subplots was high. Spatial distribution methods revealed a tendency toward clumping in both forest types, and both had similar size class structures, suggesting that both environments are suitable for C. guianensis. This new finding illustrates the potential for C. guianensis management in terra firme forests. High densities and clumped distributions in both forest types are also indices favorable for sustainable species management. Finally, several ecological variables (tree density and reproductive potential) were sufficiently different between terra firme and occasionally inundated forests to recommend stratification by forest type when conducting further studies on key ecological and management variables of C. guianensis.     

广东廉江次生季雨林主要建群种空间分布(英文)

根据所调查样方的树种综合优势比值，对广东西部(粤西)廉江谢鞋山次生季雨林最重要的三个建群树种，进行了空间格局分析。分析方法采用了Poisson分布、负两项分布、Neyman分布的频次比较模型和聚合度指数测定以及Taylor指数和 Iwao's 方程模拟。结果表明这三个建群种均符合聚集分布。荔枝（Litchi chinensis ）和山杜英（Elaeocarpus sylvestris）两种群有基本型聚集分布的特点并表现出个体间的聚集现象。橄榄（Canarium album）有可能随着密度的增大而趋于均匀分布。树种的空间分布格局依赖于其繁殖特性之外，还受该次生季雨林保护的影响。这些主要建群种的空间格局表明进行该林区保护的迫切性。     

The effect of participatory forest management on the livelihood and poverty of settlers in a rehabilitation program of degraded forest in Bangladesh

The sal forest is the only plainland forest in Bangladesh, and is of national economic and environmental importance. High population and ever increasing poverty has stimulated exploitation of the forest alarmingly and brought it near extinction. In facing this situation, the Bangladesh Forest Department implemented a participatory management approach, involving the householders living in and around the forests, for forest maintenance and protection. This study examines the effectiveness of practicing participatory forestry on the settlers’ livelihood in the encorached area of the sal forest. The settlers were given degraded and encroached forest land through the program. Two major social forestry models — namely agroforestry and woodlots — are included in the study. Participation in the resettlement increased household income, employment opportunities and financial and non-land assets. It was found that the participatory management regime could attain the sustainability of the forest and accelerate the standard of settlers’ livelihood, hence the program is an efficient management option towards sustainability of the forest resources. These findings suggest that there is a role for extending the approach to rehabilitate other degraded and encroached forest lands in Bangladesh.     

建设二滩水电站库区防护林体系的探讨

针对二滩水电站库区水土流失的现状,提出实施库区防护林体系的分类建设技术,并探讨了有关的建设保障措施.     

月溪乡生态公益林建设现状和存在的问题及对策

通过对月溪乡生态公益林的建设现状进行分析,指出了月溪乡生态公益林建设存在的突出问题,并提出要从科学规划、改善林分质量、创新管护机制、规范资金管理、科学利用等方面推进月溪乡生态公益林建设可持续发展的对策.     

豫东平原农区林种结构调查研究

以2003年商丘市森林资源调查资料为基础,用层次分析法调整商丘市的林种结构,结果表明,调整后的林种结构比调整前更适合于商丘市的实际。其结果显示,在保证生态效益的前提下应该适当的增加特殊用途林和用材林的比例,来满足商丘地区的实际需求,但生态林与经济林6︰4的总比例不变,这样能在满足可持续发展的生态需求前提下加快经济的发展。     

苏北沿海地区不同模式农田林网胁地效应的研究

从野外测定和理论估算两个方面，分析了苏北沿海地区杨树和水杉农田林网的胁地范围，结果表明：这两种模式农田林网存在着不同程度的胁地作用，且网格组成林带的胁地范围有着明显的差异，南林带量严重，水杉林网为１．０Ｈ；；杨树林网为１．５Ｈ；东、西林带其次，水杉林网为０．５－０．８Ｈ；杨树林网为１．０Ｈ；北林带胁地范围不明显。在胁地范围内，水杉林网的小麦减产率约为杨树林网的一半（北林带除外）。     

辽河源国家森林公园的山杨林

对辽河源国家森林公园山杨林的种类组成、外貌、结构、林木蓄积、死地被物贮量及其最大持水量进行了调查与研究。结果表明,山杨林的植物种数为47种,林木蓄积量为195.3 m3/hm2,死地被物贮量为17.7t/hm2;最大持水量为21.9 t/hm2。     

不同经济发展阶段下我国的森林资源利用与保护

森林资源是经济发展过程中重要的投入要素,不同经济发展水平下的森林资源利用与保护具有明显的阶段性特征,反映了人类对森林资源的认识程度和发展林业的核心目标。依据经济发展阶段划分的相关理论,本文将我国的经济发展划分为4个阶段,研究了各发展阶段森林资源利用与保护的特点。分析认为:随着经济总量增加和经济增长方式的转变,森林利用的形式从单一趋向综合,对森林质量的要求不断提高,并决定着森林保护的形式和力度。     

江西省珠江流域防护林体系工程建设经验与对策建议

以实施完成的珠江流域防护林体系建设二期工程为例分析江西省珠江流域防护林体系建设成效,总结珠江流域防护林体系工程建设经验特点和工程建设中存在的主要问题,并对后期工程建设提出对策、建议。     

凤凰山林场建设的问题,成因及对策

分析探讨了国营凤凰山林场建设中存在的问题、成因及其对策。