采用林分平均高和密度估计人工林蓄积量

采用2015年广西森林资源连续清查第9次复查中人工林样地调查数据,按树种组(杉木、松树、桉树)建立林分每公顷蓄积量与林分平均高、林分密度(郁闭度、每公顷林木株数)二元非线性模型(不变参数和可变参数),用确定系数(R~2)和平均预估误差(MPE)等6个指标对模型进行评价和检验。结果显示:全部12个模型的总相对误差(TRE)、平均系统误差(MSE)均小于15%,MPE均小于10%,表明采用林分平均高和密度估计林分单位面积蓄积量可取得较好的效果,但可变参数模型的参数的变动系数太大,不宜采用;3个树种组中,不论是不变参数模型还是可变参数模型,以平均高和每公顷林木株数构建的模型的R~2均大于由平均高和郁闭度构建的相应模型的R~2,而剩余标准差(SEE)、MPE则相反,说明每公顷林木株数对林分每公顷蓄积量变动的解释能力优于郁闭度。综合考虑6个统计指标和参数的稳定性,3个树种组的每公顷蓄积量的最优估计模型均为由每公顷林木株数、平均高构建的不变参数模型。     

不同起源林分胸径与材积株数分布比较研究

取材于９年、１７年、２７年３个龄组的天然林与人工林，分别按胸径与材积株数分布进行比较。分析结果表明：①胸径株数分布除２７年人工林向右偏斜外，其余均为左偏，而其削度均为负值，即胸径株数分布曲线均比正态曲线平坦；②材积株数分布均为左偏，削度除２７年为负值外，其余均为正值，即材积株数分布曲线均比正态曲线尖削；③均值显著检验结果除９年生天然林与人工林材积有显著差异（０．０５水平）外，其余均无显著差异。     

用EXCEL计算林分平均胸径

利用Microsoft EXCEL软件在重复计算方面的优势,对林分平均胸径进行计算,实际使用效果良好。     

林分生态因子平均高与胸径的测算

文章论述了林分平均高和优势平均高与平均胸径的测算方法,林分平均高同胸径之间的关系,林分平均高与平均胸径在森林调查中的重要作用。只有正确的测算林分平均高与平均胸径,才能更好地利用和发挥森林资源的生态作用,促进人与自然和谐发展。     

杉木林分蓄积量不同测定方法的比较

以同一块杉木林分为对象,对9种常用的林分蓄积量测定方法进行对比分析,提出了在不同条件下的最佳测定方法无测树用表或相关数学模型时以等株径级标准木法较好,测树用表或数学模型齐全时最好采用形高表法.     

朝阳市主要树种组林分平均胸径生长率模型研究

采用超总体理论编制朝阳市油松、刺槐、杨柳、速生杨4个树种组林分平均胸径生长率通用模型,以2005年森林资源二类调查资料为原始数据,涵盖全市所有地区不同地理位置和不同立地条件的生长水平.建立4种模拟方程,通过拟合与优化及结果精度的检验,选择出各树种组的平均胸径生长率模型.     

林分平均胸径100倍圆公式在随机抽样中的理论论证

对文献[1]提出的在林分中作样圆随机抽样,分别采用样圆直径为林分平均胸径100倍和样圆直径为林分平均胸径目测值的100倍园法测定每公顷断面积的新方法,笔者从样本统计分析上分别推导与论证了林分平均胸径100倍圆公式G/hm2=N0与修正公式G/hm2=N.K的理论成立性。     

BP神经网络在林分平均胸径生长预估中的应用

以2005年12月～2007年3月期间在滇中地区调查的55块云南松天然次生林标准地数据为实验数据，阐述在MATLAB平台上如何使用BP神经网络建立林分平均胸径生长模型，并对所建模型效果进行评价．     

对《林分平均胸径100倍圆法测定每公顷断面积的理论初探》一文的审稿意见

该文的结论是“以林分平均胸径的100倍为直径作圆形样地，得出林分每公顷胸高断面积等于圆形样地圆内的林木株数加上圆界上林木株数的一半”的结论。     

基于三维激光扫描的单木胸径和树高提取

为了提高林分尺度下单木参数的识别精度,研究了基于三维激光扫描的单木胸径和树高的辨识方法。在东北林业大学实验林场,采用Trimble S60三维激光扫描仪,对104株蒙古栎进行多测站扫描,获得样本树的点云数据。在对点云数据进行配准、去噪、地形数据提取、切片栅格化等一系列处理基础上,基于霍夫变换和连续生长法分别构建了胸径和树高的提取方法,对林分尺度下单木定位识别、胸径和树高提取精度进行了对比分析。研究结果表明:所构建方法单木定位识别精度均值为87.50%,胸径和树高提取的均方根误差分别为2.88 cm、2.61 m。     

Generalized functions of biomass expansion factors for conifers and broadleaved by stand age,growing stock and site index

Parties to the Kyoto Protocol and/or the United Nations Framework Convention on Climate Change (UNFCCC) are required to account for their direct human-induced carbon emissions and removals including those from forestry and other land use related activities. In most European countries, the forestry related greenhouse gas inventories are largely or exclusively based on converting tree volume data from national forest inventories to biomass using biomass conversion and expansion factors (BCEFs). However, country specific data for many species are often lacking, which considerably increases the uncertainties of the greenhouse gas inventories. The focus of this research was to develop, using internationally published datasets that cover a large geographical area, an extended set of generalized curves of such biomass expansion factors for several species or species groups by age, growing stock and site index.     

基于无人机影像与Mask R-CNN的单木树冠检测与分割

对无人机遥感影像中单木树冠进行检测与分割并获取树冠冠幅与树冠面积参数,可以为城市中不同场景下的林业资源调查提供高效快捷的途径.以银杏树为研究对象,创建基于无人机遥感影像的银杏单木树冠数据集,并使用卷积神经网络Mask R-CNN算法结合正射影像图对城市中不同场景下的树冠进行检测和树冠边界勾绘以获取相关树冠参数.结果表明...     

Estimation of taper curve using stand variables and sample tree measurements

The aim of the study was to develop methods for estimating the taper curves for trees tallied in a forest inventory. The average stem form in a stand was described by the principal components of the stand effects in the stem dimensions measured in the polar coordinate system. Measurements of diameter at breast height, diameter at a height of 6 meters, and height taken from trees on the sample tree plots were used for determining the first four principal components. Regression models were derived to predict the principal components from the site and growing stock variables. These models were used to estimate the taper curves of the tallied trees. Use of the principal components estimated by the regression models gave less reliable results than use of the principal component estimates based on measurement of the height of one randomly chosen tree on the sample plot. The best result was found with combined use of the principal component estimates and one height measurement per sample plot.     

建立相似林分样木因子回归模型推算采伐木蓄积

在安化县杉木人工林相似林分内设立样地,测量样地对角线上26株林木的地径、胸径和树高,用Excel软件建立地径与胸径、胸径与树高的回归模型,再测量采伐木地径,用回归模型预测采伐木的胸径和树高,推算采伐木蓄积量。同时,采用地径一元立木材积表法测算林木蓄积量,并与采伐作业设计的二元立木材积表法测算的林木蓄积量相比较。结果表明:采用建立相似林分样木因子回归模型推算采伐木蓄积量方法接近采伐作业设计的蓄积量。     

A hypothesis about the interaction of tree dominance and stand production through stand development

The development of forests over time involves changes in rates of growth of trees and stands, and changes in the competition and dominance between trees plays a large role in the overall development of stands. A hypothesis proposes that changes in the growth of trees and stands result from regular changes in dominance and the efficiency of resource use by dominant and non-dominant trees. Dominance is low prior to canopy closure, and efficiency of resource use is high for all trees. Increasing dominance near canopy closure reduces the efficiency of resource use by non-dominant trees, lowering overall stand growth. Later in stand development, the efficiency of resource use also declines for the largest trees, reducing the level of dominance in the stand. The dominance part of this hypothesis was examined for 150 years of stand development in two mixed-species stands in the Coast Range of Oregon. A quantitative index of dominance was minimal prior to the peak in stand growth near age 25–30 years, and then increased sharply as stand productivity declined. Dominance then declined after age 100 years as the growth rate of the 300 largest trees/ha began to decline. The dominance portion of the hypothesis was supported, and further testing may be useful.     

Prediction of the amenity of a tree stand

Slides and computer drawings of 100 managed stands were evaluated for scenic beauty and recreational value by 121 people. The size and age of trees increased the beauty and recreation scores as well as a big share of pines and birches. A great number of stems per hectare indicated low amenity. Characteristics describing the tree population explained 70 % of the variation in slide ratings. Ratings of computer illustrations of stands accounted for about the same proportion of the variation in slide ratings indicating that they can be used as successfully as the regression models for estimating the amenity of a tree stand. The ratings of forestry students did not differ from those of biology students nor the ratings of foresters from those of urban citizens.     

Modelling root rot incidence in Sweden using tree,site and stand variables

Decay and root rot caused by Heterobasidion annosum (Fr.) Bref. s. lato is the most serious disease of Norway spruce [Picea abies (L.) Karst.]. Mathematical models of disease development have recently been developed for forestry planning purposes. Functions for predicting the probability of decay were developed from two data sets, one comprising trees and another comprising stumps. From the years 1983–2001, 45,587 Norway spruce trees from the Swedish National Forest Inventory (NFI) were analysed for decay incidence at 1.3 m height and correlation with environmental conditions. The decay frequency increased in all studied regions from the first to the second half of the period for trees with comparable tree and environmental attributes. In a stepwise logistic regression, sets of functions were developed showing significance regarding stand age, site index class, temperature sum, height above sea level, diameter at 1.3 m, soil moisture and texture, proportion of spruce and eastern coordinates. The functions were calibrated and validated with a data set from the Swedish NFI from the years 1993–2002 comprising 7,893 stumps. The calibration of decay incidence at breast height to stump height doubled the decay incidence (R ²=0.85). The developed functions could be used to establish initial conditions for dynamic modelling of disease and in strategic planning.     

Detection of individual trees and estimation of tree height using LiDAR data

For estimation of tree parameters at the single-tree level using light detection and ranging (LiDAR), detection and delineation of individual trees is an important starting point. This paper presents an approach for delineating individual trees and estimating tree heights using LiDAR in coniferous (Pinus koraiensis, Larix leptolepis) and deciduous (Quercus spp.) forests in South Korea. To detect tree tops, the extended maxima transformation of morphological image-analysis methods was applied to the digital canopy model (DCM). In order to monitor spurious local maxima in the DCM, which cause false tree tops, different h values in the extended maxima transformation were explored. For delineation of individual trees, watershed segmentation was applied to the distance-transformed image from the detected tree tops. The tree heights were extracted using the maximum value within the segmented crown boundary. Thereafter, individual tree data estimated by LiDAR were compared to the field measurement data under five categories (correct delineation, satisfied delineation, merged tree, split tree, and not found). In our study, P. koraiensis, L. leptolepis, and Quercus spp. had the best detection accuracies of 68.1% at h = 0.18, 86.7% at h = 0.12, and 67.4% at h = 0.02, respectively. The coefficients of determination for tree height estimation were 0.77, 0.80, and 0.74 for P. koraiensis, L. leptolepis, and Quercus spp., respectively.     

湖南速生、中生、慢生阔叶树组单株生长模型构建

[目的]研究湖南速生、中生、慢生阔叶树组的生物量碳计量参数,构建相关生长模型,以期为湖南省林业碳汇项目大面积的开发奠定基础。[方法]以湖南省速生、中生、慢生阔叶树组为研究对象,利用收集和调查的生物量、解析木实测数据,选择不同数学模型,通过曲线回归、非线性回归方法拟合模型参数,建立阔叶林碳汇基线情景、项目情景下的碳汇计量方程,并进行模型精度检验。[结果]不论是基线情景,还是项目情景,幂函数模型均是各阔叶树组的单株生物量模型的最优模型;各阔叶树组胸径、树高生长模型形式各异,对于胸径生长模型,两种情景多以S模型拟合效果最好,对于树高生长模型,两种情景多以Logistic模型拟合效果最好。[结论]所建两种情景各阔叶树组的生长模型预测精度均达到了90%以上,均通过了F检验,适用于估算各阔叶树组不同情景下的碳汇量。