落叶松天然林株数分布的研究与应用

以落叶松天然林１８９块标准地为材料，求解了各标准地威布尔分布概率密度函数参数。参数普遍随直径的增大而增大，随密度增大而降低。据此建立了林分因子与参数、参数间Ｒｉｃｈａｒｄｓ拓广模型。参数模型与密度、直径模型结合较佳；通过精度检验表明了Ｒｉｃｈａｒｄｓ拓广模型正确性。模型可动态预测林分株数分布，为森林抚育间伐设计各生长阶段间伐方法、强度、预测林分蓄积等提供依据。     

落叶松人工林林分因子模型的建立

利用落叶松人工林所设标准地的观测数据, 求算各标准地的威布尔分布参数a、b、c, 并将其与林分因子: 平均直径、上层平均树高、株数密度结合, 建立了Richards3种林分因子模型。经检验其精度达到96 7 % ~97 7%, 通过进一步检验表明, 密度、上层高、直径模型优于其他两种模型, 可在森林经营上应用。     

豫西日本落叶松林分密度与直径关系的探讨

文中以豫西日本落叶松人工标准地为材料，用多元回归方法，求解出日本落叶松人工林各地位指数级的郁闭度、密度株数级与林分平均直径的关系。该关系将为森林抚育间伐，林分直径生长量预测、预报．确定林分工艺成熟以及森林调查设计等，提供理论依据及重要参数。     

思茅松人工林林分密度控制图的编制与应用

在思茅松人工林集中分布的西双版纳、思茅地区的 10个县 (市 ) ,按照立地条件、年龄、郁闭度、生长状况等的不同 ,设置 16 6块标准地 ,用以编制林分密度控制图 ,包括等树高线、等直径线、最大密度 (饱和密度 )线、等疏密度线、等自然稀疏线等 5条曲线 ,根据密度控制图可以求算林分蓄积量、疏密度、优势高 ;可以求算林分间伐量、间隔期进行间伐设计 ;可以预测各生长阶段的平均胸径、生长量等。经检验等树高线精度为 96 1% ,等直径线精度为 97 8%。     

闽北杉木人工林最优收获量表的研究

利用302块杉木人工林标准地材料，以密度二次效应模型为基础，采用动态规划方法建立可变间伐间隔期的林分经营密度模型，配合形高模型及林分变量之间存在的数量关系，编制了杉木人工林最优收获量表，为抚育间伐和生长预测等提供了科学依据。     

杉木各林分疏密度条件下林分密度与平均直径关系的研究

文中以杉木人工林标准地为材料,用多变量逐步回归方法,求解出杉木人工林各地位指数、疏密度级、密度株数级之林分平均直径。结果表明:经理论分析证明,不论林分疏密度之高低,当林分疏密度及密度株数相同时,其林分平均直径在各立地奈件下较接近或趋于一致。此规律将为森林抚育间伐,林分直径生长量预测、预报,确定林分工艺成熟以及森林调查设计等,提供理论依据及一些重要参数。     

贵州马尾松人工林直径分布动脉转移模型研究

以15块经营密度试样地资料为基础，用转移概率矩阵方法建立马尾松人工林直径分布动脉转移模型。模型在间伐试验林的高、中、低密度林分中的应用结果表明，林分总断面积的预测精度依次为97％，98％，98％。同时表明，比例法的应用精度普遍高于公式法。     

落叶松人工林下层间伐前后直径、蓄积度关系的研究

以落叶松人工林标地为材料，求解了等树高线、复合等树高－直径线数学模型，据此研究下层间伐前后直径，蓄积度的数量关系及变化规律。结果表明：同一株数间伐强度，不论上层高、蓄积度大小，直径增长率、蓄积度下降率一致：建立了以株数间伐强度与直径增长率、蓄积度下降率的数学模型，该模型准确地反映了数量关系和变化规律，为预测不同株数间伐强度及伐后直径、蓄积度等提供依据和参数。     

秃杉人工林密度管理技术研究

对秃杉人工林开展不同造林密度和抚育间伐试验研究 ,结果表明 :随秃杉造林密度增加 ,其胸径、冠幅和整齐度减少 ,枝下高增大。单株生物量随林分密度增加而减少 ,林分生物量及树干和根系占全部生物量比率随密度增大而增加 ,枝条和针叶所占比率随密度增加而减少 ,根据培育目标 ,用下层间伐及中度间伐可切实有效地提高林分生物量和生长量     

湿地松林分间伐对材种结构的影响研究

根据间伐8年后的湿地松林分生长和主伐造材调查结果，建立了胸径和断面积等与林分保留密度及本底断面积的回归关系，分析比较了不同间伐强度对林木径阶分布和造材材种结构的影响效果。研究结果表明，间伐后林分保留密度对林木胸径和断面积生长以及材种结构等均产生显著影响；尾径20cm及以上规格的材种出材率随间伐强度增大而增大，而14cm及以下规格的材种出材率则随间伐强度的增大而减小。不同伐对照总的出材量虽比间伐的大，但增加的部分主要为较小规格的材种。     

Dependences of longleaf pine （Pinus palustris） natural reproduction on environments above ground

We studied relations between natural seedling reproduction and above ground environment in a longleaf pine ecosystem. Forty-eight 0.05 ha circular plots were sampled under single-tree selection, group-tree selection and control stands in three main longleaf pine areas in south Alabama, USA. We measured six above-ground environment factors, viz. canopy closure, stand density, basal area, average tree height, understory cover and PAR under canopy. We employed forward, back-ward and stepwise selection regression to produce one model. Three main variables：canopy closure, stand density and basal area, were left in the model; light, PAR and understory cover were not incorporated into the model at the 0.10 significance level. Basal area was a positive pa-rameter, while canopy closure and stand density were negative parame-ters. Canopy closure was the main parameter in the model. The model proved to be meaningful, and has potential to provide useful guidance for future work.     

‘Relationships between relationships’ in forest stands: intercepts and exponents analyses

Relationships between diameter at breast height(dbh) versus stand density, and tree height versus dbh(height curve) were explored with the aim to find if there were functional links between correspondent parameters of the relationships, exponents and intercepts of their power functions. A geometric model of a forest stand using a conic approximation suggested that there should be interrelations between correspondent exponents and intercepts of the relationships. It is equivalent to a type of ‘relationship between relationships’ that might exist in a forest stand undergoing self-thinning, and means that parameters of one relationship may be predicted from parameters of another. The predictions of the model were tested with data on forest stand structure from published databases that involved a number of trees species and site quality levels. It was found that the correspondent exponents and intercepts may be directly recalculated from one another for the simplest case when the total stem surface area was independent of stand density. For cases where total stem surface area changes with the drop of density, it is possible to develop a generalization of the model in which the interrelationships between correspondent parameters(exponents and intercepts) may be still established.     

日本落叶松人工林生长预测的全林分模型研究

以长岭岗林场日本落叶松人工林中的固定样地以及临时样地调查数据为基础，从模型间的相容性出发，建立了包含立地指数SI、林分密度SDI、林分断面积生长模型、树高曲线动态模型和林分收获模型的全林分模型系统，着重探讨了用Korf方程构造林分断面积生长模型时有关参数与SI和SDI的关系。     

Modelling the edge effect in even-aged Monterey pine (Pinus radiata D. Don) stands

Six edge effect models are presented. Modelling results for the edge effect on the DBH, total height, crown height, and basal area in even-aged stands of Monterey pine (Pinus radiata D. Don) are provided. Free edges and edges under external competition pressure were analysed. Model fitting was carried out in two phases. In the first phase, independent fittings for each border type by sampled cardinal point in each stand were carried out to detect differences in edge effect intensity and depth according to edge aspect. In the second fitting phase, the best models selected by edge aspect in the first phase were restricted to estimate the same value for each variable in the stand interior, independently of the border where it was analysed.

The edge effect intensity and depth varied depending on the analysed variable and edge type. Modelling of the edge effect on DBH and total height on free edges of old stands requires a model with independent parameters for each border aspect; the models can be restricted to estimate the average value of each variable in stand interior. A model with independent parameters for each border aspect should be also used for modelling the effect on total height, crown height and basal area for the edges of young stands under external competition pressure. The modelling of basal area and crown height on free edges of old stands, DBH on edges of young stands under external competition pressure, and all variables mentioned on free edges of young stands can be carried out through an average fitting. DBH and basal area are directly affected by stand density; thus, modelling of edge effect on these and others variables which are affected by stand density can improve with the inclusion of a competition index or a point density index.     

Inventory and analysis of tree injuries in a rockfall-damaged forest stand

Rockfall is a major threat to settlements and transportation routes in many places. Consequently, the protective function of mountain forests has recently gained particular interest. However, much is still unknown about the ideal properties of protective forest stands. Therefore the present paper discusses a method for the inventory and analysis of tree injuries in a rockfall-damaged forest stand. With this method, the interrelation between stand geometry and rockfall injuries in a subalpine Polygalo chamaebuxi-Piceetum was examined. The study site of 0.3 Ha is located in the transit zone of frequently passing, small rockfall fragments (~10 cm in diameter) causing healable tree injuries. Tree and injury parameters were recorded and analysed as to injury number, height and size. The spatial distribution of the 157 trees (diameter at breast height dbh>5 cm) in the stand as well as of the 1,704 identified rockfall injuries showed a very uneven pattern. As expected, number, height and size of the injuries generally declined with increasing distance from the cliff as well as due to higher stem densities. In contrast, results indicated that the dbh of trees has no significant influence on the number of injuries per tree. However, this study showed a clear interrelation between tree and injury distribution: in general, large trees close to the cliff and smaller trees with a high density further down the slope seem to be favourable for good protection. At least an uneven-aged, multilayered stand should be sustained. Overall, the combined analysis of stand geometry and injury parameters provides information on the spatial distribution of rockfall and on the influence of tree arrangements.     

密度对毛竹生长的影响

本文以崇阳县毛竹为研究对象,在4种密度(1 300±100株·hm~(-2)(D1)、1 900±100株·hm~(-2)(D2)、2 500±100株·hm~(-2)(D3)及3 100±100株·hm~(-2)(D4))毛竹林分内对其主要生长因子进行了实地调查以研究毛竹林分密度效应。结果表明,虽然密度对退笋率影响不显著,但对毛竹的出笋率和成竹率有显著影响,二者都呈现出先增大后减小的趋势。毛竹林叶面积指数随林分密度的增大而增大(3.18~7.10),不同密度毛竹叶面积指数之间的差异极显著。毛竹林分平均胸径在10.75~11.75 cm,不同密度毛竹胸径之间的差异极显著。毛竹林分平均竹高在12.96~13.33 m,不同密度毛竹竹高之间的差异不显著。株数按径级分布与株数按树高级分布均符合正态分布。     

Improving the simulation of stand structure in a forest gap model

There is currently great interest in improving the applicability of forest gap models to changing environmental conditions, in order to facilitate the assessment of possible impacts of climatic change on forest ecosystems. Moreover, for the development of mitigation strategies, it is necessary to include forest management options in the models. Both the simulation of transient effects of climatic change and of forest management regimens require a realistic representation of stand structure in gap models, since tree species respond to variations in stand density in characteristic ways, depending on their ecological strategies.In this study, we compared the effect of five different height growth functions that are sensitive to stand density on simulated stand structure of the FORSKA forest gap model. We used long term observation data from a beech thinning trial at Fabrikschleichach, Bavaria, to test the alternative functions. First, we compared simulation results of the original FORSKA model with measured stand development from 1870 to 1990. Whereas simulated stand level variables (e.g. biomass, mean diameter and height) showed good correspondence with observations, individual tree dimensions and simulated stand structure were quite unrealistic. After calibrating parameters of the height growth functions with data from a lightly thinned plot at Fabrikschleichach, we ran the model with data from a heavily thinned plot for validation. All five functions considerably improved the simulation of height/diameter relationships and stand structure. However, there were distinct differences between functions. The best correspondence with measurements was shown by a function which uses the relative radiation intensity in the centre of a tree crown as an indicator of the competition status of the tree. This function is rather simple and needs only two growth parameters, which can be derived for different functional types of species, according to their shade tolerance.With the new, flexible height growth function it should be possible to extend the applicability of gap models to more realistic simulation experiments including forest management and natural disturbance. To our knowledge, this was the first attempt to employ long term forest observation data for the calibration and validation of a forest gap model. The results suggest that such data could be very useful in model testing and improvement.     

A model for predicting log yield from stand characteristics

A method for forecasting the log‐class distribution resulting from harvesting forest stands is investigated. The diameter distribution of a stand is approximated by a two‐parameter Weibull density function, the parameters of which are recovered from stand level characteristics. Theoretical bucking is performed for actual and simulated distributions and the resulting log yields are compared. An application to 40 stands indicates that an accurate prognosis can be expected, given a good approximation of the diameter distribution. For cases with multimodal diameter distributions or many small trees, the prognosis is unreliable.     

黄冕林场桉树人工林经营利用与经济效益分析

对广西黄冕林场3-5年生桉树人工林进行生长调查,探讨分析桉树经营利用经济效益。结果表明：桉树人工林中,不同林龄和同一林龄桉树人工林之间生长差异明显。不同的立地条件、初植林分密度对桉树人工林胸径、树高等生长影响很大。随着林分密度（标准地样木数）的增大,样木数与生长指标之间具有较强的负相关性。随着林龄的增大,这种林分密度负效应就越明显。从财务指标看,随着林龄的增大,总产值、纯利润和NPV均呈现增大的趋势,但IRR却并不如此,而是先增大后减少,在4a时,IRR达到最大值。从年份看,投资回收期为3a。结果表明桉树在广西黄冕林场这样的立地条件和气候条件下,表现适生、速生,且经济效益好,是营造短周期用材林的好树种。但为获得好的经济效益,必须注意树种、立地条件和栽培等措施的选择。