声－超声技术评价兴安落叶松规格材的抗弯性质

测量落叶松规格材的波速、峰值电压、时间形心和频率形心等声－超声参数,以及气干密度、抗弯弹性模量和抗弯强度等物理力学性质,研究声－超声参数、气干密度、动态弹性模量等与抗弯性质之间的相关性。为了探索利用声－超声技术预测落叶松抗弯性质的可行性,分别以动态弹性模量和声－超声参数及气干密度为自变量,建立预测其规格材抗弯性质的回归模型。结果表明：所有的声－超声参数、气干密度与抗弯弹性模量均在0.01水平显著相关,峰值电压、频率形心、气干密度与抗弯强度在0.01水平显著相关。利用气干密度、峰值电压和波速3个参数为自变量建立的抗弯弹性模量和抗弯强度的预测模型的相关性(决定系数 r2分别为0.83和0.66)与传统的超声波方法(以动态弹性模量为自变量建立的抗弯弹性模量和抗弯强度预测模型,r2分别为0.80和0.34)相比,模型的预测能力显著提高。利用声－超声技术能够较好地预测落叶松规格材的抗弯力学性质,特别是抗弯强度。     

基于代理技术的森林植被模拟系统的研究

FVS(Forest Vegetation Simulator)森林植被模拟是美国农业部林务局主持开发的,它起源于对森林生长和产出的预测和管理[1],并可以使用相关图形软件模拟出图形化的预测直接效果.森林植被模拟技术作为一个新的研究方向越来越多的受到林业研究者的关注,该技术在预测、监测、再现和控制森林立木蓄积资源等方面对林木直径结构转移方程有了一定的应用研究[2];在森林火灾方面,也可基于林火三维蔓延的数学模型和计算机仿真进行模拟[3].     

性信息素监测预报马尾松毛虫的应用研究

针对马尾松毛虫危害严重、预测预报困难等问题,本文应用性信息素监测技术,对湖北省孝感市大悟县6个镇(林场)近0.53万hm~2马尾松林进行了马尾松毛虫预测预报的研究。结果表明,该技术能够准确预测马尾松毛虫发生发展动态,年均预测预报精度达92.32%。     

基于Max Ent模型的北京浅山区珍稀植物适生区预测及管理

对北京浅山区珍稀植物分布生境进行研究可以掌握生境动态并使珍稀植物保护更具效率。文章利用最大熵生态位模型(MaxEnt)与地理信息系统(Arc GIS),结合108个珍稀植物分布数据、经相关性筛选后的各项气候因子及7个与珍稀植物生存相关性强的环境因子,对珍稀植物潜在分布和适宜等级作出预测,并据此构想相关管理策略。研究结果表明:1) Maxent模型对珍稀植物在北京浅山区潜在分布区的预测效果较好,接近非常好的水平,地表起伏度、bio4、水(分)等因子对预测结果贡献率最大; 2)预测适生区集中分布在十渡、石花洞、九龙山、蟒山、唐指山、四座楼等区域,在此基础上,以“最适生区”和“较适生区”为重点关注对象,对于不同地区选择了不同的保护策略。     

北美雷击火概率预测技术及其应用效果评价

从模型结构、预测原理、建立方法、应用效果和未来发展等几个方面,对北美,特别是加拿大安大略省雷击火概率预测模型进行了介绍,并探讨了该模型在我国大兴安岭地区的适用性,使国内相关领域的研究人员能够比较全面地了解此系统,可为建立适用于我国林区雷击火的概率预测系统提供参考。     

加拿大森林火行为预测系统应用及展望

森林火灾频发给我国造成了严重的森林资源损失和其他方面的损失。而我国在森林火行为预测预报研究方面水平较低,还无法准确地对火灾进行预测。加拿大森林火行为预测系统（FBP系统）可以利用森林可燃物类型、气象条件、地形地势及火行为特征等因子准确有效地对森林火行为进行预测预报,对林火管理人员制定灭火计划和组织火灾扑救工作具有十分重要的意义。文中介绍了FBP系统的主要结构和工作原理,以及系统内部参数和预测预报所需的相关数据,概述了该系统在加拿大的实际应用情况,对我国建立森林火灾预报、火行为预测系统进行了展望。     

森林资源调查监测年度数据产出方法研究

利用2021年国家林草生态综合监测评价北京市样地数据及相关资料,基于“1/5+4/5”联合估计方案,提出回归抽样估计和回归模型预测2种基本估计方法;同时还针对部分省份存在多个副总体和加密样地等特殊情况,提出了采用分层抽样和联合估计方法产出年度数据,并以北京市森林蓄积量估计为例,以4套方案开展计算。结果显示,基于老样地估计的2套方案,全市森林蓄积量估计精度均在92%以上,其中方案2(基于回归模型预测)的总体抽样精度从方案1(基于回归抽样估计)的92.87%提高到93.87%;采用加密新样地和老样地联合估计的2套方案,全市森林蓄积量估计精度均在94%以上,其中方案4的总体抽样精度从方案3的94.24%提高到94.65%。研究表明：采用回归抽样估计和回归模型预测2种基本方法对当年未调查样地进行数据更新的方法,在实践中是完全可行的;综合利用回归抽样估计、回归模型预测、分层抽样方法和联合估计方法,可以解决存在副总体和加密样地等不同情况下的年度数据产出问题。     

红松果林经营技术与产业发展前景预测

红松是我国重要的名贵树种,为国家Ⅱ级重点保护野生植物。本文论述了红松资源分布特点、遗传改良方法、天然林与人工林经营、经济果林营建等相关技术,并对产业发展优势进行了分析预测。     

引入环境变量的香格里拉市高山松碳储量估测

森林碳储量是森林固碳能力的重要参考指标,准确估算森林碳储量对陆地碳循环具有重要意义。以香格里拉市1987—2017年Landsat TM/OLI遥感影像、森林资源连续清查数据和地形数据为主要数据源,利用Pearson相关性法、Spearman相关性法、Kendall’sτ相关性法、距离相关性法和决策树法筛选预测变量,并引入不同环境变量结合随机森林(RF)模型估测香格里拉市高山松碳储量。结果显示：(1)在不同方法筛选出的预测变量中,偏度、角二阶矩等纹理因子与高山松碳储量相关性最高;(2)通过决策树法筛选出的变量组合所构建的RF模型效果最优,其R²为0.845,RMSE为10.076 t/hm²,rRMSE为29.254%,P为0.747;(3)引入环境变量后,精度都有不同程度提升,其中地表温度对模型精度的提升最高,其R²提高了4.80%,RMSE降低了1.71 t/hm²,rRMSE降低了5.391%,P提高了6.60%;(4)1987—2017年,香格里拉市高山松碳储量时空变化较明显,高山松碳储量增...     

国内外对榆蓝叶甲综合防治技术的研究及进展

国内、外对榆蓝叶甲的生物学及生态学习性、发生规律与预测预报等方面研究的比较深入,特别是在物理、化学、生物与天敌防治等综合防治方面做了广泛的研究,发表了许多相关的研究论文,文章就国内外对榆蓝叶甲防治方面的研究结果做了较详细概述。     

基于MODIS数据的山东省森林植被与水汽相关分析研究

以山东省森林为研究对象,利用MODIS的大气水汽产品、山东森林分布图等对大气水汽与森林植被的关系进行了研究,结果表明：水汽的变化很快,有明显的运动、传输过程;水汽含量的分布与当时的风速、风向、天气状况、地形等有着密切的联系;下午各地水汽含量差异不明显,夜间各地水汽含量比白天低;林区分布的对大气水汽含量的日变化影响不显著,下午森林对大气水汽的调节作用比较强。     

预应力混凝土空心板"蒸养"裂纹产生与防范

在预应力空心板冬季“蒸养”过程中，混凝土初期养护管理、升降温梯度、板粱上下散热速度差以及梁内是否配置防裂钢筋等都将对粱的浇注质量产生影响，本文以伊嘉公路五汤段的预应力空心板粱为例，对粱的“蒸养”裂纹作了详细分析，提出了相应的防范措施。     

基于FLAASH模型的Landsat ETM＋卫星影像大气校正

主要介绍FLAASH大气校正原理及算法,并运用FLAASH大气校正模型对美国旧金山地区ETM＋卫星影像进行大气校正,再对校正前后的影像进行地物光谱曲线分析和NDVI分析评价。研究表明,ETM＋卫星影像经FLAASH大气校正后,较好地消除了大气影响。     

Numerical Simulation of the Interaction between Forest Ecological System and Atmospheric Boundary Layer

Based on the basic principles of the micrometeorology of atmospheric boundary layers and vegetation canopy, a numerical model of the interaction between forest ecosystems and atmospheric boundary layers was developed. The model is used to simulate the diurnal variations of heat balance in forest ecosystems, canopy temperatures, ground surface temperatures, as well as the profiles of temporal and spatial distributions of potential temperatures, wind speeds, specific humidity, and turbulence exchange coefficients. Our study indicates that the model can be applied to study the interaction between land surface processes and atmospheric boundary layers over various underlying surfaces and their regional climate effects. This paper will establish a solid foundation to investigations on the coupling of climate models and the biosphere. Translated from Chinese Journal of Applied Ecology, 2004, 15(11) (in Chinese)     

Image-based reflectance conversion of ASTER and IKONOS imagery as precursor to structural assessment of plantation forests in KwaZulu-Natal,South Africa

Reflectance-converted imagery is a requirement for establishing temporally robust remote sensing algorithms, given the reduction of time-specific atmospheric effects. Thus, in this study image-based atmospheric correction methods for ASTER and IKONOS imagery for retrieving surface reflectance of plantation forests in KwaZulu-Natal, South Africa were evaluated. This effort formed part of a larger initiative that focused on retrieval of forest structural attributes from resultant reflectance imagery. Atmospheric correction methods in this study included the apparent reflectance model (AR), dark object subtraction model (DOS), and the cosine approximation model (COST). Spectral signatures derived from different image-based models for ASTER and IKONOS were inspected visually as first departure. This was followed by comparison of the total accuracy and Kappa index computed from supervised classification of images that were derived from different image-based atmospheric correction of ASTER and IKONOS imagery. The classification accuracy of DOS images derived from ASTER and IKONOS imagery exhibited percentages of 93.3% and 94.7%, respectively. Classification accuracies for images from AR and COST, on the other hand, resulted in lower accuracy values of 87.9% and 83.6% for ASTER and 90.5% and 92.8% for IKONOS, respectively. We concluded that the image-based DOS model was better suited to atmospheric correction for ASTER and IKONOS imagery in this study area and for the purpose of forest structural assessment. This has important implications for the operational use of similar imagery types for forest inventory approaches.     

广西主要森林类型效益计量及经济评价

参考有关资料及国家林业局发布的《森林生态系统服务功能评估规范》（LY/T1721-2008）标准对广西森林生态系统进行效益计量并通过效益转换和货币置换,将森林多种效益货币化。结果表明：广西壮族自治区主要森林类型生态服务效益总价值为4 989.299亿元,其中固碳释氧467.78亿元,保育土壤382.189亿元,涵养水源2 378.72亿元,森林游憩367.74亿元,生物多样性保护1 085.52亿元,净化大气307.35亿元。研究结果将为广西林业产业发展＂56820＂行动计划、＂绿满八桂＂工程以及政府部门＂十二五规划＂的相关决策提供基础参考数据。     

Variation in shoot water status of Picea abies (L.) Karst. trees with different life histories

Daily dynamics of the shoot water potential (ψ) in Norway spruce [Picea abies (L.) Karst.] depending on soil water availability and atmospheric evaporative demand was studied on originally freely-grown trees and suppressed trees exposed to full sunlight after clear-cutting. The base water potential (ψ_b) was significantly correlated (R² = 0.73) with the available soil water storage (W_tr) at a depth of 20–40 cm. ψ_b was relatively constant at high soil water status and decreased sharply if W_tr dropped below 14 mm. Among the atmospheric factors observed, the vapour pressure deficit (VPD) proved to be the most relevant variable in predicting diurnal changes in ψ. The leaf water status was more sensitive to VPD at sufficient soil water storage. With soil drying, the daily amplitude of ψ diminished, testifying to the more efficient stomatal control under soil drought. For predicting the daily course of ψ from VPD and ψ_b (taken as a measure of the soil water availability) an empirical model was derived, which described 78–80% of the total variatin in the shoot water potential. In contrast to values of ψ_b, the daily values of ψ differed significantly (P < 0.05) between the trees with different life histories. The newly exposed trees demonstrated substantially lower values of ψ with increasing atmospheric evaporative demand at the same soil water availability. Dynamic water stress is considered one of the main causes of the continuing growth retardation in suppressed spruce trees after their release from overstorey.     

Effect of Harvest of Old Growth Douglas-fir Stands and Subsequent Management on Carbon Dioxide Levels in the Atmosphere

A simple stand model is developed to assess the influence of management activities in old growth Douglas-fir forests on atmospheric CO, levels. Two natural disturbance regimes (450- and 240-year stand replacement fire cycles) are compared with four management regimes (45, 6 5 , 90-year plantation rotations, and conversion to non-forest use). Conversion of old growth Douglas-fir stands to plantations may actually decrease atmospheric C 4 for the fist few decades, but then increase it. The short term and long term changes are negligible compared to the atmospheric C02 produced by burning fossil fuels. Using wood as a substitute product for other materials (brick, aluminum, and plastic) dramatically reduces CO, released to the atmosphere; however, where wood is used as a luxury product, large quantities of C02 are released to the atmosphere under harvest regimes.     

Separating effects of changes in atmospheric composition,climate and land-use on carbon sequestration of U.S. Mid-Atlantic temperate forests

Terrestrial carbon dynamics have been vastly modified because of changes in atmospheric composition, climate, and land-use. However, few studies provide a complete analysis of the factors and interactions that affect carbon dynamics over a large landscape. This study examines how changes in atmospheric composition (CO₂, O₃ and N deposition), climate and land-use affected carbon dynamics and sequestration in Mid-Atlantic temperate forests during the 20th century. We modified and applied the PnET-CN model, a well established process-based ecosystem model with a strong foundation of ecosystem knowledge from experimental studies. We validated the model results using the U.S. Forest Inventory and Analysis (FIA) data. Our results suggest that chronic changes in atmospheric chemistry over the past century markedly affected carbon dynamics and sequestration in Mid-Atlantic temperate forests, while climate change only had a minor impact although inter-annual climatic variability had a far more substantial effect. The NPP response to a century of chronic change in atmospheric composition at the regional scale was an increase of 29%, of which, 14% was from elevated CO₂, 17% from N deposition, 6% from the interaction between CO₂ and N deposition, and minus 8% from tropospheric ozone. Climate change increased NPP by only 4%. Disturbed forests had 6% lower NPP than undisturbed forests after seven decades. Regrowing forests after harvesting and natural disturbances had much greater capacity for sequestering carbon than undisturbed old-growth forests even though the newer forests had slightly lower net primary production (NPP). The modeling results indicated that N deposition was a stronger force than elevated CO₂ for increasing NPP and fast turnover tissues, while elevated CO₂ favored more sustainable carbon storage and sequestration. The model results are consistent with various experiments and observations and demonstrate a powerful approach to integrate and expand our knowledge of complex interactive effects of multiple environmental changes on forest carbon dynamics.     

Long-term sustainability of forest ecosystems on sandstone in the Vosges Mountains (France) facing atmospheric deposition and silvicultural change

Since the 1980s, atmospheric deposition acidity has generally decreased in European forest ecosystems. However, at many sites, little or no sign of recovery has been observed yet. Concerns are rising about the sustainability of these ecosystems because of reduced nutrients inputs in atmospheric deposition and the increase in biomass harvesting to supply bio-energy.We used a silver fir plot of the French monitoring network (RENECOFOR, site SP57) typical of the ecosystems on sandstone in the Vosges Mountains, to investigate its functioning and its response facing past and possible future changes. We (1) calculated 12-year-mean “input-output” nutrient budgets, (2) measured the change in soil exchangeable cations and anions, (3) used monitoring data to calibrate a process oriented biogeochemical model, NuCM, that was then used to (4) simulate the consequences of two main scenarios and their combinations: constant or reduced atmospheric deposition, and traditional or whole-tree harvesting.Mean term changes in exchangeable nutrients and input-output budgets showed a loss of exchangeable sulphate and base cations, the level of which depended on the method. This combined efflux induced an acidification of soil solution and an alkalinisation of the soil. The model NuCM was successfully calibrated and scenarios were implemented. A slight recovery was simulated when deposition was maintained constant but combined acid and nutrient atmospheric deposition reduction delayed recovery. Whole-tree harvesting drastically decreased soil fertility compared to traditional silviculture. Hence, biomass harvesting in forests on poor soils may counter recovery in the future.