Heuristic planning techniques applied to forest road profiles

Two heuristic techniques, the genetic algorithm (GA) and Tabu search (TS), both with an embedded linear programming routine for earthwork allocation, were compared to a manually designed forest road profile. The manually designed road length was 345.7m and its average gradient was 14.1%. The best costs of the profiles designed by GA and TS, without changing the placement of control points, were less than that designed manually. The best cost found by GA was almost the same as the global optimum solution. While TS could not find a better solution than GA, it usually found a good solution in less time. It was not possible to search all alternatives by changing the placement of control points and find the global optimum solution within a reasonable time. However, it can be concluded from the results that both GA and TS found good solutions within a reasonable time. Since it is not possible to manually evaluate many alternatives, road designers should find heuristic techniques helpful for design of the road profile. Moreover, the effect of the number of control points on construction costs was examined. The results indicated that increasing the number of control points reduces the construction costs. However, driving safety and comfort might be decreased.     

Application of an airborne laser scanner to forest road design with accurate earthwork volumes

In this study we developed a forest road design program based on a high-resolution digital elevation model (DEM) from a light detection and ranging (LIDAR) system. After a designer has located the intersection points on a horizontal plane, the model first generates the horizontal alignment and the ground profile. The model precisely generates cross-sections and accurately calculates earthwork volumes using a high-resolution DEM. The model then optimizes the vertical alignment based on construction and maintenance costs using a heuristic technique known as tabu search. As the distance between cross-sections affects the accuracy of earthwork volume calculations, the results were examined by comparing them with the exact earthwork volume calculated by the probabilistic Monte Carlo simulation method. The earthwork volumes calculated by the Pappus-based method were similar to those calculated by the Monte Carlo simulation when the distance between cross-sections was within 10m. The model was applied to a high-resolution DEM from the LIDAR of Capitol Forest in Washington State, USA. The model generated a horizontal alignment, length 827m, composed of five horizontal curves. We examined the number of grade change points. The results indicated that tabu search found the best solution ($61.42/m) with five grade change points. This was composed of two vertical curves that almost followed the ground profile. As the accuracy of a high-resolution DEM from LIDAR increases, the model would become a useful tool for a forest road designer because it eliminates or at least reduces the time-consuming process of road surveys.     

Spatially explicit assessment of forest road suitability for timber extraction and hauling in Switzerland

Efficient forest management, and wood production in particular, requires a forest road network of appropriate density and bearing capacity. The road network affects the choice of a suitable extraction method and the length of the transport route from the forest, while the road standard defines the truck type that can be used.

We evaluate the forest road network’s economic suitability for harvesting operations in the entire Swiss forest, an area of about 13,000 km² covering a range of topographies, based on the Swiss National Forest Inventory’s (NFI) forest road dataset. This dataset is based on information from an interview survey with the local forest services and includes all forest roads in Switzerland capable of carrying trucks. Extraction options and hauling routes are analysed together; thus, the entire logging process is examined.

Model results include maps of the most suitable extraction method; extraction costs; hauling costs; and a suitability map based on a combination of the results. While the larger part of the Swiss forest is classified as “suitable” for economic harvesting operations, significant portions also fall into the “limited suitability” and “not suitable” categories. Our analysis provides an objective, country-wide, spatially explicit assessment of timber accessibility. The resulting suitability map helps identify areas where timber harvesting is economic using the current forest road network, and where it is not. The model results can be used in road network planning and management, for example, by comparing road-network re-design scenarios, and compared to the spatial distribution of available wood volume.

     

树木、林内、林冠上与森林区风速廓线研究

One of the most important and frequently studied variable in forests and the most basic element in governing transport processes of airflow is wind speed. The study of wind profile, defined as the change of wind velocity with height, and wind velocity are important because of tree physiological and developmental responses. Generally, wind profiles above the ground or at a canopy surface follow classical logarithm law, but wind profiles in a single tree and in a forest stand are not logarithmic. This paper summarizes the results of wind profile studies within a single tree, in a forest stand, above the forest canopy and in a forest area from recent research in a coastal pine forest. The results demonstrate that: 1) wind profiles with in a single conifer tree crown showed an exponential function with height, 2) wind profiles in forest stands were able to be expressed by attenuation coefficient of wind, 3) wind profiles over a forest canopy could be determined using profile parameters (friction velocity, roughness length and displacement), and 4) for a forest area, the extreme wind speed could be predicted reasonably using the methods developed for the design of buildings. More research will be required to demonstrate: 1) relationships between wind profiles and tree or stand characteristics, 2) the simple methods for predicting wind profile parameters, and 3) the applications of wind profile in studies of tree physiology, forest ecology and management, and the detail ecological effects of wind on tree growth.     

Tabu search optimization of horizontal and vertical alignments of forest roads

This article describes a program for optimizing horizontal and vertical alignments of forest roads using Tabu search, a modern heuristic technique. Once a series of intersection points (IPs) is selected manually, the program generates alternative horizontal and vertical alignments. The program precisely generates ground profile and cross sections using a high-resolution digital elevation model (DEM) derived from light detection and ranging (LiDAR) data. It accurately calculates earthwork volumes for curved roadways using the Pappus-based method. The program also estimates construction and maintenance costs. Tabu search optimizes forest road alignments based on the total costs. The application of the program to part of Capitol State Forest in Washington State, USA, indicated that the program successfully found better alignments than manually selected initial alignments. The effect of initial solutions and the number of iterations on the Tabu search process was examined. The result showed that the solutions were improved using the best solutions with the smaller number of grade change points as the initial solutions. It also showed that a small number of iterations could be used to reduce computation time due to the fact that Tabu search is based on a gradient search technique. Finally, the Dijkstra method was examined to find initial solutions without manually initialized solutions. The program, when combined with the Dijkstra method, could find similar-quality solutions from manually initialized solutions. The program will become useful with further tests and verifications.     

Constructing forest plans interactively based on owner-driven evaluation of the holding- and stand-level alternatives

In this study, an interactive forest planning process corresponding to the practical demands was developed and further tested in a challenging forest planning situation in northeastern Finland. The process includes prior preparation of alternative stand-level treatments and a small amount of holding-level forest plans; an interactive planning session consisting of the primary choice of the forest owner's profile; the owner's selection of the best holding-level plan; and finally a local improvement of this plan. The method as a whole aims to bridge the gap between the prevailing planning culture that has developed for private forest planning over three decades in Finland and the planning approach suggested by multiobjective forest planning theory. The usability and characteristics of the process were evaluated through an exercise set given to both forestry students and forest professionals. Tests of the process indicated, among other things, that comparison particularly of stand-level alternatives and offering owners the possibility to make changes and truly affect the end-result of the planning process are seen as important characteristics of the process.     

浅谈东北林区道路规划思想转变的必要性

基于林区可持续发展战略的高度,从东北林区道路规划理论、林区经济发展预测、道路功能转变的角度,分析了东北林区道路规划理念转变的必要性,提出林区道路规划指导原则,为解决东北林区道路规划问题提供参考.     

New strategies for estimation of cut and fill areas in road design with different ground cross-section offsets

Earthwork operations accounted for great amount of forest road construction costs. Any Optimization in planning road profile needs a reliable objective function that calculates earthwork volume in an appropriate time and accuracy. This study aimed at incorporating the shape of the ground cross sections in calculating cut/fill areas using three alternative methods including: Multiple Linear Regression (MLR), Artificial Neural Network (ANN) and heuristic programming in MATLAB environment. The accuracy of results was validated via AutoCAD as a manual method for area calculation of road’s cross-section. Trapezoidal method applied to calculate the area of cut/fill in the heuristic method. Paired sample T-Test and statistical analysis (ANOVA) with confidence level of 0.95 indicated that the heuristic method not only reduced computing time but also provided accurate estimations as same as the manual AutoCAD based method. It can be concluded that although MLR and ANN estimations were as well as AutoCAD results within a reasonable time, they need to be retrained by adding, removing or changing entrance parameters.     

Roads, fire and aggressive competitors: Determinants of bird distribution in subtropical production forests

Forestry practices such as fuel-reduction burning and maintenance of road networks can negatively impact avian assemblages, both directly by changing habitat structure and indirectly by creating conditions favorable for predators or competitors. The Brigalow Belt forests include some of the largest contiguous areas of native forest in the temperate and sub-humid zones of eastern Australia. Over 1 million ha of these forests are proposed to be converted from forestry to conservation tenure, yet the impacts on the avifauna of current and potential future forest management practices are not known. We investigated the influence of road edges and habitat type and structure on the avifauna of a 356 000 ha forest. Survey sites were either <50 m or >300 m from a road, and in either cypress pine Callitris glaucophylla forest, spotted gum Corymbia citriodora forest with a regenerating cypress pine/buloke Allocasuarina luehmannii understorey or spotted gum forest with an open understorey due to fuel-reduction burning. The avifauna differed significantly among vegetation types but not with proximity to a road, with the greatest differences between cypress pine and both types of spotted gum forest. The noisy miner Manorina melanocephala, an aggressive avian competitor, appears to be the factor mediating these assemblage-level differences. Noisy miners were rare in cypress pine forest but were three times more numerous than any other species in spotted gum forest. Spotted gum forest with a regenerating understorey had fewer noisy miners. Although total bird abundance was highest in open spotted gum forest, the species richness and abundance of passerines smaller than noisy miners was significantly lower in this forest type. Abundance of small passerines was eight times higher in sites where <3 noisy miners were recorded. Only one species, the eastern yellow robin, was influenced by proximity to a road edge. Cypress pine forest is potentially an important refuge for smaller birds. The results suggest that burning regimes that reduce regeneration of the cypress pine and buloke subcanopy in spotted gum forest potentially are exacerbating the problem of noisy miner domination of the avifauna.     

关于林道开发效率评价的研究

本文在论证和分析影响林道开发效率的主要因子的基础上,提出了用林道开发效率系数来评价林道开发效率的方法。这是评价林道开发效率的一种简单而实用的新方法。研究结果表明,按林道开发效率系数趋近于1时所对应的路同密度来修建林道,可获得最佳的伐区开发效率。     

基于工程造价比较法的森林公园道路设计方案选优——以东莞市森林公园的园区道路建设为例

文章以东莞市4个森林公园的园区道路建设案例,采用数理统计的方法,分析了公开招投标项目中施工图预算的量价关系,阐述降低园区道路建设成本的科学方法,最后提出如何用工程造价比较法判断森林公园道路勘测设计的经济合理性。     

Climate risks and forest practices: forest owners' acceptance of advice concerning climate change

Based on qualitative interviews with Swedish forest owners this study focuses on climate change, risk management and forest governance from the perspective of the forest owners. The Swedish forest governance system has undergone extensive deregulation, with the result that social norms and knowledge dissemination are seen by the state as important means of influencing forest owners' understandings and practices. Drawing on Foucault's concept of governmentality this study contributes knowledge on how forest owners understand and manage climate-related risk and their acceptance of advice. From the interview study, three main conclusions can be drawn: (1) forest owners' considerations largely concern ordinary forestry activities; (2) knowledge about forest management and climate adaptation combines experiences and ideas from various sources; and (3) risk awareness and knowledge of “best practices” are not enough to ensure change in forestry practices. The results of this study show that the forest owners have to be selective and negotiate about what knowledge to consider relevant and meaningful for their own forest practice. Accordingly, local forest management can be understood as situated in a web of multifarious interests, claims, concerns and knowledges, where climate change adaptation is but one of several aspects that forest owners have to consider.     

Remote sensing analysis of forest damage by selection logging in the Kabaung Reserved Forest, Bago Mountains, Myanmar

Selection logging is a principal management scheme in natural teak-bearing forests in Myanmar. Monitoring the spatial extent and intensity of selection logging is important for sustainable forest management. This study applied the normalized difference vegetation index (NDVI) image differencing method using two SPOT-5 pan-sharpened images (2.5 m spatial resolution) taken in October 2007 and January 2009 to analyze canopy changes associated with damage from forest harvesting. According to the pixel-based analysis, NDVI changes were larger in most logging road/log landing points whereas smaller NDVI changes were seen in most unlogged points. NDVI changes in teak stump areas were related to distance from a logging road and the number of stumps within the estimated crown area (a circular area with a 10 m radius from the center of each stump). A Fisher’s exact test showed that one of the main factors causing the high NDVI change in teak stump areas was the effect of road construction. The distribution pattern of teak stumps indicated that teak stumps with estimated crown areas that contained more than one stump had high mean change in NDVI. The spectral difference between before and after logging revealed that logging roads had a greater effect on canopy changes than teak stumps.     

广州机场路景观防护林的环境效应特征

为了计量城市路网景观防护林的环境效应,采用群落生态学及水平多点定位同步观测方法,对机场路景观防护林群落结构及消减路面热岛、污染气体浓度效应进行了观测研究;结果显示:防护林群落呈4层垂直结构(上层乔木平均高(珚H)=12.6 m、中层乔木珚H=6.3 m、灌木层珚H=3.2 m、草本层珚H=0.6 m),水平30 50 m沿机场路侧带状分布;防护林群落的Shannon(H)达2.39,均匀度达0.76,而森林群落郁闭度达0.68。相对路面空气SO2、NO2(0.150、0.083 mg·m-3)的日均浓度,防护林林内20 m则减小到0.05 mg·m-3以下,空气温度则减小2.0℃,空气湿度增加2.4%,风速减小0.7 m.s-1;雨季晴天日,13:00-15:00、林内20 30 m空间相对路面的气温减小值大于2.0℃,而林内10 30 m空间相对路面的空气湿度增加5.0%7.1%;林内20 30 m空间空气SO2浓度≤0.05 mg·m-3的白昼持续时间达8.3 9.0 h,而林内30 40 m空间空气NO2浓度≤0.05 mg·m-3的白昼持续时间达8.3 h;机场路景观防护林群落对路面热岛强度、空气SO2、NO2浓度消减效应极其显著。采用趋势面回归方法,获得的机场路面至林内水平尺度空气SO2、NO2浓度时空分布拟合方程适宜于估算应用。     

Evaluation of surface smoothness by laser displacement sensor 1: effect of wood species

The best methods for determining surface roughness in an industrial environment are of the noncontact variety, with reproduction of the profile. The objective of this work was to compare the roughness profile obtained by a contact stylus with a commercial laser displacement sensor (LDS). Measurements were done using 15 wood species with different densities and colors, based on which special triangle profiles were prepared. The accuracy of the laser sensor was examined by statistical analysis of roughness parameters measured from the profiles. Experimental results show that LDS profiles were imitated correctly. However, LDS accuracy depends on the scanned wood properties (density and color), installation position of the sensor, and profile shape. It was found that evaluation of dark and high-density wooden surfaces was imperfect.Part of this work was presented at the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, April 2000; and at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 2001     

基于随机森林的大姚县TM遥感影像分类研究

随机森林(Random Forest)是一种组合多棵决策树分类器的新的分类算法。以楚雄州大姚县为例,采用Landsat-TM数据,通过最大似然、支持向量机、随机森林3种分类器进行分类对比研究。结果表明,支持向量机和随机森林的分类精度明显优于最大似然法,两者分类精度相差不大;在分类时间上,最大似然法明显比随机森林和支持向量机快,支持向量机最慢。综合分析,随机森林算法表现更优,它在保证分类精度的前提下,也能保证一定的时间效率,更适宜实际生产应用。     

Does the effect of forest roads extend a few meters or more into the adjacent forest? A study on understory plant diversity in managed oak stands

Roads are recognised as having different ecological roles such as barrier, corridor or habitat, but the spatial extent of road effects on plant communities in forests remains unclear. We studied the effect of forest road distance on plant understory diversity at 20 sites in young and adult oak stands in a French lowland forest with a long history of management and road construction. All vascular and bryophyte species were collected at five distances ranging from the road verge to 100 m into the adjacent forest stand. We analysed species composition, individual species response, a priori life-history traits response – life form, habitat preference and dispersal mode – and environmental indicator values in relation to road distance and stand age. Plant composition strongly differed between road verge and forest interior habitats. The main road effect extended less than 5 m into the forest stand. A third habitat was detected at the forest-road edge resulting from the road effect on light and soil conditions, and from edge-specific topography. Non-forest species were almost absent from the forest interior. In contrast, many bryophytes and several vascular plants kept away from the road. We identified a posteriori six species groups that better explained the variability of plant response profiles than a priori life-history traits. Plant response to road distance was also dependent on stand age: some species colonised from the road into the forest interior in young stands following regeneration cutting, while other species displayed the reverse pattern in adult stands once canopy closed above the forest road. Even if the depth of forest road effect measured in lowland managed stands was narrow, building of a new forest road has non-negligible effects on plant population dynamics. Forest managers should take into account the impacts of roads on biodiversity, since the expected intensification of silviculture in response to global changes is set to accentuate the effect of forest roads. We recommend further study on the role of dispersal by vehicles (i.e. agestochory) in road effects.     

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     

论林道网的技术评价

林道网的评价是对原有路网进行技术改造和森林开发中进行休道网规划设计工作的重要组成部分,不经过认真的评价,就难以作出林道网规划方案的科学决策。本文在深入研究林道网技术评价的基础上.提出并推荐使用林道网密度、适应性、顺达性、吻合性和平均车速等6项评价指标,从而使林道网的技术评价工作有了较完整的指标体系,以利于林道网的实际评价工作。     

Land cover analysis in wildland-urban interfaces according to wildfire risk: A case study in the South of France

Each year, forest fires destroy about 500,000 ha of vegetation in Europe, predominantly in the Mediterranean region. Many large fires are linked to the land transformations that have taken place in the Mediterranean region in recent decades that have increased the risk of forest fires. On the one hand, agricultural fallows and orchards are slowly being colonized by vegetation, and on the other hand, the forest is not sufficiently used, both of which result in increased accumulation of fuel. In addition, urbanization combined with forest extension results in new spatial configurations called “wildland-urban interfaces” (WUI). WUI are commonly defined as “areas where urban areas meet and interact with rural lands, wildland vegetation and forests”. Spatial analyses were performed using a WUI typology based on two intertwined elements, the spatial organization of homes and the structure of fuel vegetation. The organization of the land cover in terms of representativeness, complexity or road density was evaluated for each type of WUI. Results showed that there were significant differences between the types of WUI in the study area. Three indicators (i) “fire ignition density”, derived from the distribution of fire ignition points, (ii) “wildfire density”, derived from the distribution of wildfire area and (iii) “burned area ratio”, derived from the proportion of the burned area to the total study area were then compared with each type of WUI. Assuming that the three indicators correspond to important aspects of fire risk, we showed that, at least in the south of France, WUI are at high risk of wildfire, and that of the different types of wildland-urban interfaces, isolated and scattered WUI were the most at risk. Their main land cover characteristics, i.e. low housing and road densities but a high density of country roads, and the availability of burnable vegetation such as forested stands and shrubland (garrigue) explain the high fire risk. Improving our knowledge of relationships between WUI environments and fire risk should increase the efficiency of wildfire prevention: to this end, suitable prevention actions and communication campaigns targeting the types of WUI at the highest risk are recommended.