落叶松锉叶蜂为害的松林光谱特征分析

通过对不同程度危害的落叶松反射光谱进行测定,研究了不同程度危害的落叶松在绿光区、红光区和近红外区反射光谱的变化特征,并对光谱反射曲线进行微分分析。结果表明,绿光区、红光区和近红外区的落叶松光谱反射率随危害程度的加重分别呈现下降、上升和下降的趋势;对反射率曲线进行微分分析,健康落叶松、轻度、中度和重度为害后的一阶导数光谱反射率最大值随着危害程度增加而下降,并且向短波方向移动(蓝移)。实测光谱数据提取的归一化植被指数(NDVI)与落叶松锉叶蜂危害程度呈显著负相关,对应用遥感技术早期监测落叶松锉叶蜂灾害具有重要指示意义。     

基于信息量模型的西溪流域崩岗风险评估

崩岗是发生在我国南方红壤区的严重的土壤侵蚀现象,不仅破坏了当地的生态环境并且直接影响了生产生活,因此崩岗发生的风险评估是崩岗预警需要解决的关键问题之一。以福建省泉州市安溪县的西溪流域为研究区,筛选崩岗的主要影响因子,借助信息量模型构建崩岗风险评估体系,并评估研究区的崩岗风险。结果表明:河网缓冲距离、海拔高度、相对高差、坡度、坡向、土壤类型、植被覆盖度以及土地利用类型可作为评估崩岗发生的主要风险因子;风险因子的梯度分析结果表明,河网缓冲距离近,坡度15°~35°的阳坡,海拔100~500 m,相对高差>50 m,土壤类型为红壤、赤红壤,植被覆盖度0~20%或40%~80%和土地利用类型为园地、未利用地的区域易发生崩岗;以河网缓冲距离、海拔高度、相对高差等8个筛选因子构建信息量模型,采用接受者操作特征(ROC)曲线对评价结果进行检验,对应的曲线下面积为0.827,精度结果良好。信息量模型对崩岗发生风险评估结果良好,可应用于小流域尺度范围的风险评估。     

Post-fire habitat restoration of sables during winter season in northern slope of the Great Xing＇an Mountains

Habitat loss and fragmentation have been associated with the decline of endangered species. In 1987, a catastrophic fire in the northern Great Hing＇an Mountains of China, where the main habitat of sables （Martes zibellina） is located, aggravated the loss and fragmentation of the forest landscape. Due to restricted distribution and low population density, sables were listed in the national first-grade protected species in China. The objective of this paper was to identify to what extent the habitat of sables had been restored 13 years after the fire. Based on the behavioral data, which came from field survey information by radio-tracking, GPS （Global Positioning System） and forest inventory data, suitability habitat maps were derived using the Ecological Niche Suitability Model （ENSM）. In addition, the habitat structure was analyzed with selected landscape indices. Although forest cover mostly had been restored by 2000, the results indicated that, compared to the pre-fire situation, the areas of suitable habitat had been reduced significantly, especially those of less suitable, marginally suitable and moderately suitable designation. Fragmentation was aggravated, and suitable patches were found to be further isolated with the exception of those in most suitable areas. The ratio of the patch perimeter to area in unsuitable, moderately suitable and suitable areas decreased, while the ratios within other suitability types increased. Moreover, the percentage of soft boundaries decreased slightly, which can influence the redistribution of sables. The results above indicated that the suitable habitat had deteriorated, and the restoration of the sables＇ habitat remained to be done.     

Usefulness of biophysical proxy data for modelling habitat of an endangered forest species: The white-backed woodpecker Dendrocopos leucotos

Abstract

Efficient conservation planning in managed forest landscapes requires knowledge about the location of functional habitat for specialised species. We explored the importance of different variables to predict habitat suitability for the white-backed woodpecker (Dendrocopos leucotos Bechstein), a proposed umbrella species in deciduous forest. Specifically, we tested whether biophysical proxy variables indicating management intensity and the occurrence of natural processes constituted a useful complement to traditional remotely sensed data on tree species composition and forest stand age for modelling the woodpecker's habitat. Presence–absence of the woodpecker during the study period (1986–2006) in southwestern Sweden was explained by the area of edge habitats (forest bordering water or farmland) and wetland forest, and location relative to the historical marine limit. The number of years with occurrence of the woodpecker in a territory was explained by the area of forest bordering water and wetland forest. Among traditional forest variables, the area of deciduous forest had a strong positive effect on both woodpecker presence–absence and the number of years with occurrence. The results support the hypothesis that edge habitats and forest types subject to natural processes favouring deciduous trees and dead wood creation are valuable to the woodpecker and should be prioritised in conservation planning.     

基于关键气象因子的油茶种仁含油率预测模型构建

含油率是油茶重要的经济性状,构建油茶含油率预测模型对于茶油产量预报有重要的意义。本研究以普通油茶为研究对象,通过分析油茶种仁含油率与不同气象因子的关系,确定影响油茶种仁含油率的关键气象因子,然后用回归分析法构建基于关键气象因子的油茶含油率预测模型,并用独立资料检验预测模型效果。结果表明:8月月平均气温、8月月最高气温、9月月最高气温、油脂转化积累高峰期最高气温与含油率呈显著的负相关关系。通过逐步回归分析法拟合得到了3个油茶含油率预测模型,用独立资料检验后,发现基于9月降水量(x1)、9月月最高气温(x2)和油脂转化积累高峰期最长连续无降水天数(x3)的油茶种仁含油率(y)预测模型(y=79.46-0.03x1-0.86x2-0.30x3)效果好,平均相对误差为4.6%,可应用于普通油茶种仁含油率预测。     

Introducing GIS-modelling into the management of a brown rat (Rattus norvegicus Berk.) (Mamm. Rodentia Muridae) population in an urban habitat

The landscape of three test areas of an urban environment was efficiently assessed for its ability to support brown rats (Rattus norvegicus Berk.) by successfully integrating habitat suitability modelling using GIS (Geographical Information System). The GIS model, validated using an independent set of rat observations, and a model analysis showed the potential of different habitats for rat occurrence. Because of its use of general land-cover types, the model could be applied to other cities. This model system will be used for the entire city area of Salzburg in the near future. In this publication, we present the results of the pilot GIS model.     

可燃物含水率与气象因子相关关系预测模型的研究

可燃物含水率大小决定森林燃烧的难易程度。利用中科院长白山定位站提供的气象数据,通过可燃物含水率与气象因子的相关分析,筛选预测因子,并通过多元一次回归分析建立可燃物含水率与气象因子关系模型。结果表明,林内温度、相对湿度、降雨量、连续无降雨日数与可燃物含水率相关性较强,经数学检验,可燃物含水率模型模拟效果良好。     

马尾松人工林地表可燃物负荷量动态模型的研究

设立64块标准地,应用回归分析,建立马尾松(Pinus massonianaLamb)林分地表可燃物载量与主要林分因子动态关系的数学模型。检验结果表明,林分因子对马尾松林分地表可燃物载量变化有极显著的影响,林分郁闭度主要影响地表1h时滞可燃物载量变化,林分平均年龄主要影响地表10 h时滞可燃物载量的变化。在实际中拟合效果良好,可用于预测马尾松人工林地表可燃物载量的动态规律,为地表可燃物管理提供科学的依据。     

Relationship between age,size, fecundity and climatic factors in <Emphasis Type="Italic">Panax wangianus</Emphasis> an endangered medicinal plant in the sacred grove forest of North-East India

Panax wangianus (Syn. Panax pseudoginseng) S. C. Sun (Araliaceae) is a critically endangered, medicinal plant of North-East India. The objective of this study was to determine how plant size affects flowering phenology and to evaluate the effect of climatic factors on flowering, fruiting and seed production. Data on vegetative and repro- ductive characters were monitored from 2016 individuals of Panax wangianus population in Law Lyngdoh, Smit sacred grove in Nongkrem, Shillong, India. Leaflet area was measured by a planimeter. Size variables of both vegetative and reproductive traits in different age classes were measured. Climatic factors were recorded from 2007 to 2009. Age was recorded by counting the number of bud scale scars on the rhizome. Light intensity and relative humidity were measured using a photometer, LiCor Model LI-189 and thermohygrometer respectively. Different climatic variables are correlated with vegetative and reproductive phenological events. Statistical analysis revealed that a strong positive correlation was observed between the age versus vegetative and reproductive characters, except 1%-2% plants showed neoteny. Morphological variations were observed in natural conditions on the basis of the number of prong and carpellate conditions. Phenological status revealed that most of the individuals of the age class 35-50 years and above 50 years contributed the most to flowering, fruiting and seed production. Age class was significant to predict the size of the plant and its reproductive capacity. Climatic factors such as temperature, precipitation and relative humidity show synergistic effect on both the vegetative and reproductive phases in Panax wangianus in the undisturbed Nongkrem sacred grove. The color of flowers of P. wangianus also varied depending upon the sunlight intensity. Therefore, in the view of conservationand management, the age class of 35-50 years and above 50 years is the most important for population sustainability.     

Predicting the spatial distribution of the abundance of Siebold’s beech in a montane cool-temperate region based on environmental factors

Using a geographic information system (GIS), our goal was to predict the potential distribution of Siebold’s beech (Fagus crenata Blume) in a montane cool-temperate region at a fine spatial resolution based on topographical features. The study was conducted in Akashibayama National Forest in the village of Kamikawa, Niigata Prefecture, central Japan. Species composition was investigated in 28 sample plots selected in the study area. A digital elevation model (DEM) was created, and topographical, hydrological, and light factors were calculated using the DEM. Then, the relationship between species composition and these environmental factors was examined using tree-based multivariate regression to derive regression trees. The species composition for the six major species selected, which included Siebold’s beech, was used as the response variable, and environmental factors were used as explanatory variables. For the derived tree-based regression model, the shaded relief, slope, specific catchment area, and curvature were selected as explanatory variables. The model classified natural vegetation into six forest types, and the result was consistent with the moisture preferences of these major species. The model was applied to the GIS to predict and map the species composition of the major species, especially the relative basal area of Siebold’s beech.     

Use of the management-oriented silvopastoral model ALWAYS: Calibration and evaluation

The ALWAYS model simulates the biophysical functioning of a silvopastoral plot – here the broad-leaved tree — pasture — sheep association — and its management, according to the interactions between the different components of the system. The model was calibrated for two silvopastoral plots with contrasting soil and climate: at Lamartine in central France (wet upland climate), and at Cessous in southern France (a moderate hot and dry Mediterranean climate). The actual plot management recorded in the field was used in the model (and particularly date and number of grazing animals) and the model was run for different time series (from 2 to 100 years) depending on the process we wanted to evaluate, grass and animal production or tree growth. Models outputs were consistent with recorded data on the field and we concluded that the model can correctly simulate the behaviour of a silvopastoral plot in terms of tree growth, grass production, animal grazing and interactions between the different components. It permitted also to make consistent choices and compare different strategies of silvopastoral plots management. The improvement of some biophysical processes that are very simplified in the model is required to produce better accurate predictive values of sward or tree production. But a much more complex model will require more data for its parametrization and more time to run, precluding its use in many situations.This revised version was published online in November 2005 with corrections to the Cover Date.     

Evaluation of the forest growth model SILVA along an elevational gradient in Switzerland

The semi-empirical single-tree model SILVA 2.2 has been developed and parameterised using forest research and inventory data from Germany that range from the colline to the montane zone. The focus of the model evaluation presented in this study was to test the applicability of the model for the main Swiss forest types and at elevations ranging from the colline to the upper subalpine zone. To this end, SILVA was initialized using data from long-term forest yield research plots. The results at the end of the 30-year simulation were compared with observed data. The analysis of the results at each test site showed that there were no significant differences in model performance between forest types. However, the deviation between simulated and observed growth depended strongly on the elevational zone, i.e., on climate. As expected, the best results were found in the colline zone, for which the model had been calibrated, whereas the upper subalpine sites revealed the strongest differences. The quality of the data regarding forest structure that were available for model initialization had a strong impact on the simulation results, mainly at high-elevation zones (i.e., supalpine and upper subalpine). We conclude that SILVA 2.2 is a suitable tool to estimate the development of single trees and standing volume for a large fraction of the forests in Switzerland. However, extreme climate conditions should be avoided with the model, and the availability of detailed stand structure information is a key priority that has a strong effect on the quality of the simulation results.

Organizational dynamics of an information system： case study from the forestry sector

The Forest Department in the State of Uttar Pradesh, India developed Forest Management Information System （FMIS） for achieving organizational goals of improved financial and human resource management, improvement in the management of forests and wildlife, and for achieving responsive administration. This paper, based on field research, presents an assessment of the dynamics of FMIS in organizational context for a better understanding of such systems in forestry organizations. The paper also investigates the success of FMIS in assisting decision makers in achieving organizational goals. Based on the knowledge developed during the course of the study, key learning elements have been highlighted for the benefit of the stakeholders in information systems in forest sector.     

Maximally selected two-sample statistics as a new tool for the identification and assessment of habitat factors with an application to breeding-bird communities in oak forests

Near-natural forest management is one of the major principles of modern forestry in central Europe. A measure commonly used for the assessment of logging is the occurrence and density of character species typical for the local biotope. Near-natural forest structures can be designed only when sufficient knowledge about the relationship between species and habitat factors is available. We suggest the use of simple cutpoint regression models for the derivation of statistically valid rules of thumb. The methodology is applied to bird and structure data of ancient and present oak coppices with standards to demonstrate its practical application. The cutpoints are derived from estimates of break points by means of maximally selected two-sample statistics, and their validity is judged by multiple test procedures. Detailed results are presented for character species and their relationships to the environment. We show that, for example, the tree pipit (Anthus trivialis) is missing in stands with more than 40% canopy overstorey, whereas this species can be regularly observed in more open stands. For the tree pipit, the analysis is illustrated by means of a free software package.     

The four-line model of the Triangular Running Skyline system: Scale model test

The four-line model of the Triangular Running Skyline (TRS) system is the theory generalized from the previous TRS theory to treat the main and slack-pulling lines separately. The previous theory,i.e., the three-line model, treated the main and slack-pulling lines as a single line to simplify the solution. The first part of this study developed numerical procedures for the four-line model. In this paper, to empirically ascertain the accuracy of the four-line model theory, a series of static equilibrium tests was carried out using a reduced scale model of the TRS system. The result proved that the theory of the four-line model has the same accuracy as that of the three-line model. However, the result also proved that the carriage may have to be located lower than the designated height. Thus, it has been proved that the development of a certain adjusting method is necessary to move the carriage of the TRS system closer to the designated point. A part of this paper was orally presented at the Second Annual Meeting of the Japanese Forest Engineering Association, November 18, 1995, Tokyo. This English title is a tentative translation from the original Japanese by the authors of this paper.     

Fungal pathogens associated with twig canker of shrub species in Tunisia: Considering the effect of the factors correlated

Decline phenomena of shrub species such as Quercus coccifera and Retama raetam have occurred throughout Tunisian forests since 2012. These evergreen shrubs have long been regarded for their medicinal and ecological interests. Therefore, their preservation as valuable forest resources is of great interest. However, information regarding aetiology of this disease is still scarce. Hence, the aim of this study was to identify and characterize the causal agents associated with disease symptoms in two Tunisian forests. Thirty-eight isolates were obtained from symptomatic Q. coccifera and R. raetam twigs. Morphological characterization and phylogenetic analysis of the internal transcribed spacer (ITS) region of the nuclear ribosomal RNA gene cluster and partial sequence of the translation elongation factor 1-alpha gene (tef1-α) allowed the identification of three Diplodia species namely Diplodia africana, D. seriata and D. pseudoseriata. Our findings revealed that the incidence of Diplodia species was significantly correlated to the altitude, the temperature and the rainfall. Pathogenicity test showed that all Diplodia isolates are pathogenic. However, D. africana revealed to be the most aggressive species toward R. raetam. These findings were the first record of D. seriata as fungal pathogen associated with Q. coccifera dieback and D. pseudoseriata and D. africana on R. raetam in Tunisia.     

Determinants of Vietnam’s wood products trade: application of the gravity model

ABSTRACT

This study applied a gravity model estimation using panel data in order to analyze the impact of the determinants of Vietnam’s wood products trade from 2001 to 2016.The gravity estimates imply the importance of size of the economies, distance, level of openness of the economy, population, forest resource endowments of Vietnam’s trade partners, Vietnam’s logging restrictions policy, common border, free trade agreement, and exchange rates as determinants of Vietnam’s wood products trade. These variables were found to have different effects on the export and import of wood products. Vietnam’s access to the WTO and APEC did not help either its imports or exports in wood products. The results of this study also indicate that the Government of Vietnam needs to implement policies to increase investment in the wood processing industry, develop high quality wood materials from domestic plantations, and take advantage of trade preferences from new free trade agreements in order to promote wood product trade. The results of this study have implications for trade policy, resource-based economic development, and Vietnam’s forest resource conservation.     

绿色发展背景下中国林业生态效率评价及影响因素实证分析——基于DEA分析视角

【目的】为解决我国生态林业可持续性发展问题,平衡林业资源环境与林业绿色生产之间的矛盾,提升林业资源利用效率和环境效率。【方法】基于绿色发展背景,以我国生态林业生产为研究对象,挖掘整理2013—2017年我国31个省份林业生产数据,建立包含绿色生态指标的DEA模型,全面评价我国林业生态效率。选取影响林业生产的关键性因素,建立线性回归模型,分析我国林业生态效率影响因素。通过实证分析找到提升林业生态效率的政策切入点。【结果】我国在节约资源投入、提升期望产出、限制非期望产出方面有所改善,大部分地区呈现规模效率递增状态,反映出区域内林业产出的增长速度略快于资源、能源的消耗速度,在控制资源消耗、环境污染并保证林业产量的前提下,可适当扩大林业生产规模,以规模效益带动林业经济效益发展。回归结果显示:林业旅游休闲对我国林业生态效率具有正向显著性影响,在加快推动林业一二三产业融合发展的同时,需要严格控制监测林业生态建设保护、森林生态补偿、林业防治方面的投入。【结论】政策建议如下:1)控制资源消耗、环境污染与旅游规模化生产协同发展;2)加快推动林业一二三产业联动发展;3)严格控制监测林业生态建设保护、森林生态补偿、林业防治方面的投入,为我国乃至世界生态林业的绿色可持续发展提供经验和借鉴。     

年龄无关的生长模型研究—以落叶松平均高为例

目的 构建年龄无关的理论生长模型,用于年龄未知或者年龄不是有效因子的情况下的林分生长模拟。 方法 基于理论模型理查德模型,利用隐含年龄的差分形式,构建年龄无关的生长模型来拟合落叶松林分的平均高,并将自由参数表达为林分相关因子和立地因子的函数。 结果 利用刀切法对模型进行验证,时间无关的模型的修正确定系数在0.92~0.94之间,而时间相关的模型修正确定系数为0.85,时间无关的模型修正确定系数提高了8%~10%;时间无关模型的均方根误差RMSE在1.30~1.59之间,远远小于时间相关模型的20.48。年龄无关的模型之间对比,引入气候因子的模型,修正确定系数均方根误差RMSE和TRE较没有引入的有明显的降低,说明气候因子的引入提高了模型的模拟效果。 结论 可以将年龄无关的理论模型应用于年龄不可用或者不相关的林分中。采用自由参数的方式将与年龄无关的立地因子和气候因子引入模型的拟合中,对比固定参数和自由参数的两类模型,可以发现自由参数的模型表现更好。在平均高生长模型中引入立地因子和气候因子,模型效果更好。     

Wind speed and crown class influence the height–diameter relationship of lodgepole pine: Nonlinear mixed effects modeling

Wind-induced mechanical perturbation is one of the mechanisms determining the height–diameter relationship of trees, but its effects have largely been neglected in past height–diameter models. In this study, we examined the effects of including wind speed as a regressor in the height–diameter model for lodgepole pine (Pinus contorta var. latifolia Engelm.). We also tested the hypothesis that the height–diameter relationship differs between trees of different crown classes (dominant and subordinate trees), and that a mixed effects height–diameter model developed at the crown class level should achieve a better prediction than that developed at the plot level. The results showed that including wind speed significantly improved the fit of the height–diameter model. The results also showed that the height–diameter relationships differ significantly between the two crown classes. The mixed effects model developed based on crown classes of individual trees had better fit with reduced residual variance and decreased Akaike's information criterion and the Schwarz's Bayesian information criterion than the plot-based mixed model. Evaluation of the developed model suggests the crown class-based height–diameter model has better prediction in terms of prediction error and precision. The developed crown class-based mixed effects model can be used to provide more accurate prediction of tree heights for lodgepole pine from their diameters.