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A new method of calculating crown projection area and its comparative accuracy with conventional calculations for asymmetric tree crowns

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Journal of Forestry Research 2024年第4期35卷 171-188页

作者： Mingrui Zhang huiquan bi Xingji Jin Michael McLean School of Forestry Northeast Forestry UniversityHarbin 150040People’s Republic of China Forest Science NSW Department of Primary IndustriesLevel 304PSQ12 Darcy StreetParramattaNSW 2150Australia School of Ecosystem and Forest Sciences The University of MelbourneMelbourne 3010Australia

This paper introduces a new method of calculating crown projection area(CPA),the area of level ground covered by a vertical projection of a tree crown from measured crown radii through numerical interpolation and *** novel method and other four existing methods of calculating CPA were compared using detailed crown radius measurements from 30 tall trees of Eucalyptus pilularis variable in crown size,shape,and *** four existing methods included the polygonal approach and three ways of calculating CPA as the area of a circle using the arithmetic,geometric and quadratic mean *** were made across a sequence of eight non-consecutive numbers(from 2 to 16)of measured crown radii for each tree over the range of crown asymmetry of the 30 trees through generalized linear models and multiple comparisons of *** sequence covered the range of the number of crown radii measured for calculating the CPA of a tree in the literature.A crown asymmetry index within the unit interval was calculated for each tree to serve as a normative *** a slight overestimation of 2.2%on average and an overall mean error size of 7.9%across the numbers of crown radii that were compared,our new method was the least biased and most *** CPA as a circle using the quadratic mean crown radius was the second best,which had an average overestimation of 4.5%and overall mean error size of 8.8%.These two methods remained by and large unbiased as crown asymmetry increased,while the other three methods showed larger bias of *** the conventional method of using the arithmetic mean crown radius to calculate CPA as a circle,bias correction factors were developed as a function of crown asymmetry index to delineate the increasing magnitude of bias associated with greater degrees of crown *** study reveals and demonstrates such relationships between the accuracy of CPA calculations and crown asymmetry and will help increase awa

关键词： Crown radius measurements Interpolated crown contour Projected crown area Multiple comparisons of means

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Characterizing prediction errors of a new tree height model for cut-to-length Pinus radiata stems through the Burr TypeⅫdistribution

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林业研究:英文版 2023年第6期34卷 1899-1914页

作者： Xinyu Cao huiquan bi Duncan Watt Yun Li School of Information Science and Technology Beijing Forestry UniversityBeijing 100083People’s Republic of China Forest Science NSW Department of Primary IndustriesLevel 304PSQParramattaNSW 2150Australia School of Ecosystem and Forest Sciences Faculty of ScienceThe University of MelbourneWater StreetCreswickVIC 3363Australia Snowy Region Forestry Corporation of NSW76 Capper StreetTumutNSW 2720Australia

Unlike height-diameter equations for standing trees commonly used in forest resources modelling,tree height models for cut-to-length(CTL)stems tend to produce prediction errors whose distributions are not conditionally normal but are rather leptokurtic and *** feature was merely noticed in previous studies but never thoroughly *** study characterized the prediction error distribution of a newly developed such tree height model for Pin us radiata(***)through the three-parameter Burr TypeⅫ(BⅫ)*** model’s prediction errors(ε)exhibited heteroskedasticity conditional mainly on the small end relative diameter of the top log and also on DBH to a minor *** serial correlations were also present in the data.A total of 14 candidate weighting functions were compared to select the best two for weightingεin order to reduce its conditional *** weighted prediction errors(εw)were shifted by a constant to the positive range supported by the BXII *** the distribution of weighted and shifted prediction errors(εw+)was characterized by the BⅫdistribution using maximum likelihood estimation through 1000 times of repeated random sampling,fitting and goodness-of-fit testing,each time by randomly taking only one observation from each tree to circumvent the potential adverse impact of serial correlation in the data on parameter estimation and *** nonparametric two sample Kolmogorov-Smirnov(KS)goodness-of-fit test and its closely related Kuiper’s(KU)test showed the fitted BⅫdistributions provided a good fit to the highly leptokurtic and heavy-tailed distribution ofε.Random samples generated from the fitted BⅫdistributions ofεw+derived from using the best two weighting functions,when back-shifted and unweighted,exhibited distributions that were,in about97 and 95%of the 1000 cases respectively,not statistically different from the distribution ofε.Our results for cut-tolength *** stems repre

关键词： Conditional heteroskedasticity Leptokurtic error distribution Skedactic function Nonlinear quantile regression Weighted prediction errors Serial correlation Random sampling and fitting Nonparametric goodnessof-fit tests

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Comparative performances of new and existing indices of crown asymmetry:an evaluation using tall trees of Eucalyptus pilularis(Smith)

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Journal of Forestry Research 2021年第1期32卷 43-65页

作者： Fanlin Kong huiquan bi Michael McLean Fengri Li Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education School of ForestryNortheast Forestry UniversityHarbin 150040People’s Republic of China Forest Science NSW Department of Primary IndustriesParramattaNSW 2150Australia School of Ecosystem and Forest Sciences The University of MelbourneParkvilleVIC 3010Australia

Over the past 50 years,crown asymmetry of forest trees has been evaluated through several indices constructed from the perspective of projected crown shape or displacement but often on an ad hoc basis to address specifi c objectives related to tree growth and competition,stand dynamics,stem form,crown structure and treefall *** sharing some similarities,these indices are largely incoherent and non-comparable as they diff er not only in the scale but also in the direction of their values in indicating the degree of crown *** the fi rst attempt at devising normative measures of crown asymmetry,we adopted a relative scale between 0 for perfect symmetry and 1 for extreme *** existing crown asymmetry indices(CAIs)were brought onto this relative scale after necessary modifi *** new CAIs were adapted from measures of circularity for digital images in computer graphics,indices of income inequality in economics,and a bilateral symmetry indicator in plant leaf *** performances of the 13 CAIs were compared over diff erent numbers of measured crown radii for 30 projected crowns of mature Eucalyptus pilularis trees through benchmarking statistics and rank order correlation *** each CAI,the index value based on the full measurement of 36 evenly spaced radii of a projected crown was taken as the true value in the benchmarking *** index(CAI 13)adapted from the simple bilateral symmetry measure proved to be the least biased and most *** performance was closely followed by that of three other *** minimum number of crown radii that is needed to provide at least an indicative measure of crown asymmetry is *** more accurate and consistent measures,at least 6 or 8 crown radii are *** range of variability in crown morphology of the trees under investigation also needs to be taken into *** the CAIs are from projected crown radii,they can be readily extended to individual tree cr

关键词： Projected crown shape Circularity Inequality bilateral symmetry Rank order Eucalyptus pilularis

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Stochastic frontiers or regression quantiles for estimating the self-thinning surface in higher dimensions?

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Journal of Forestry Research 2021年第4期32卷 1515-1533页

作者： Dechao Tian huiquan bi Xingji Jin Fengri Li Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education School of ForestryNortheast Forestry UniversityNo.26 Hexing RoadHarbin 150040People’s Republic of China Forest Science NSW Department of Primary Industries−ForestryLevel 1210 Valentine AveParramattaNSW 2150Australia School of Ecosystem and Forest Sciences The University of MelbourneParkvilleVIC 3010Australia

Stochastic frontier analysis and quantile regression are the two econometric approaches that have been commonly adopted in the determination of the self-thinning boundary line or surface in two and higher dimensions since their introduction to the field some 20 years ***,the rational for using one method over the other has,in most cases,not been clearly explained perhaps due to a lack of adequate appreciation of differences between the two approaches for delineating the self-thinning *** an adequate understanding of such differences,the most informative analysis may become a missed opportunity,leading to an inefficient use of data,weak statistical inferences and a failure to gain greater insight into the dynamics of plant populations and forest stands that would otherwise be *** data from 170 plot measurements in even-aged Larix olgensis(***) plantations across a wide range of site qualities and with different abundances of woody weeds,*** regenerated non-crop species,in northeast China,this study compared the two methods in determining the self-thinning surface across eight sample sizes from 30 to 170 with an even interval of 20 observations and also over a range of quantiles through repeated random sampling and *** all sample sizes and over the quantile range of 0.90 ≤τ≤0.99,the normal-half normal stochastic frontier estimation proved to be superior to quantile regression in statistical *** parameter estimates had lower degrees of variability and correspondingly narrower confidence *** greater efficiency would naturally be conducive to making statistical *** estimated self-thinning surface using all 170 observations enveloped about 96.5% of the data points,a degree of envelopment equivalent to a regression quantile estimation with aτ of *** stochastic frontier estimation was also more objective because it did not involve the subjective selection of a particular value

关键词： Larix olgensis Normal-half normal distribution Site productivity Woody weeds Sample size Quantile selection

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Reconstructing the size of individual trees using log data from cut-to-length harvesters in Pinus radiata plantations: a case study in NSW, Australia

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Journal of Forestry Research 2018年第1期29卷 13-33页

作者： Kuan Lu huiquan bi Duncan Watt Martin Strandgard Yun Li School of Information Science and Technology Beijing Forestry University Forest Science NSW Department of Industry–Lands and Forestry School of Ecosystem and Forest Sciences The University of Melbourne Snowy Region Forestry Corporation of NSW Australian Forest Operations Research Alliance (AFORA) University of the Sunshine Coast

With their widespread utilization, cut-to-length harvesters have become a major source of ‘‘big data’’ for forest management as they constantly capture, and provide a daily flow of, information on log production and assortment over large operational areas. Harvester data afford the calculation of the total log length between the stump and the last cut but not the total height of trees. They also contain the length and end diameters of individual logs but not always the diameter at breast height overbark（DBHOB） of harvested stems largely because of time lapse, operating and processing issues and other system deficiencies. Even when DBHOB is extracted from harvester data, errors and/or bias of the machine measurements due to the variation in the stump height of harvested stems from that specified for the harvester head prior to harvesting and diameter measurement errors may need to be corrected. This study developed（1） a system of equations for estimating DBHOB of trees from diameter overbark（DOB） measured by a harvester head at any height up to 3 m above ground level and（2） an equation to predict the total height of harvested stems in P. radiata plantations from harvester data. To generate the data required for this purpose, cut-to-length simulations of more than 3000 trees with detailed taper measurements were carried out in the computer using the cutting patterns extracted from the harvester data and stump height survey data from clearfall operations. The equation predicted total tree height from DBHOB, total log length and the small end diameter of the top log. Prediction accuracy for total tree height was evaluated both globally over the entire data space and locally within partitioned subspaces through benchmarking statistics. These statistics were better than that of the conventional height-diameter equations for P. radiata found in the literature, even when they incorporated stand age and the average height and diameter of dominant trees in the stand as predic

关键词： Cut-to-length simulations Harvesters big data Diameter and height estimation

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A new model for predicting the total tree height for stems cut-to-length by harvesters in Pinus radiata plantations

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Journal of Forestry Research 2021年第1期32卷 21-41页

作者： Chenxi Shan huiquan bi Duncan Watt Yun Li Martin Strandgard Mohammad Reza Ghaff ariyan School of Information Science and Technology Beijing Forestry UniversityBeijing 100083People’s Republic of China Forest Science NSW Department of Primary Industries–ForestryLevel 1210 Valentine AveParramattaNSW 2150Australia School of Ecosystem and Forest Sciences The University of MelbourneParkvilleVIC 3010Australia Snowy Region Forestry Corporation of NSW76 Capper StreetTumutNSW 2720Australia Australian Forest Operations Research Alliance(AFORA) University of the Sunshine CoastSippy DownsQLD 4556Australia

A new model for predicting the total tree height for harvested stems from cut-to-length(CTL)harvester data was constructed for Pinus radiata(***)following a conceptual analysis of relative stem profi les,comparisons of candidate models forms and extensive selections of predictor *** profi les of more than 3000 trees in a taper data set were each processed 6 times through simulated log cutting to generate the data required for this *** CTL simulations not only mimicked but also covered the full range of cutting patterns of nearly 0.45×106 stems harvested during both thinning and harvesting *** single-equation model was estimated through the multipleequation generalized method of moments estimator to obtain effi cient and consistent parameter estimates in the presence of error correlation and heteroscedasticity that were inherent to the systematic structure of the *** predictive performances of our new model in its linear and nonlinear form were evaluated through a leave-one-tree-out cross validation process and compared against that of the only such existing *** evaluations and comparisons were made through benchmarking statistics both globally over the entire data space and locally within specifi c subdivisions of the data *** statistics indicated that the nonlinear form of our model was the best and its linear form ranked *** prediction accuracy of our nonlinear model improved when the total log length represented more than 20%of the total tree *** poorer performance of the existing model was partly attributed to the high degree of multicollinearity among its predictor variables,which led to highly variable and unstable parameter *** new model will facilitate and widen the utilization of harvester data far beyond the current limited use for monitoring and reporting log productions in *** *** will also facilitate the estimation of bark thickness and help make harvester data a

关键词： Stem profi les Cut-to-length simulations Harvester data Model construction Nonlinear multipleequation GMM estimation Benchmarking prediction accuracy

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Additive predictions of aboveground stand biomass in commercial logs and harvest residues for rotation age Pinus radiata plantations in New South Wales,Australia

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Journal of Forestry Research 2021年第6期32卷 2265-2289页

作者： Xixi Qiao huiquan bi Yun Li Fabiano Ximenes Christopher JWeston Liubov Volkova Mohammad Reza Ghaffariyan School of Information Science and Technology Beijing Forestry UniversityBeijing 100083People’s Republic of China Forest Science NSW Department of Primary Industries–ForestryLevel 314 Parramatta Square12 Darcy StParramattaNSW 2150Australia School of Ecosystem and Forest Sciences Faculty of ScienceThe University of MelbourneWater StreetCreswickVIC 3363Australia Australian Forest Operations Research Alliance(AFORA) University of the Sunshine CoastSippy DownsQLD 4556Australia

Two systems of additive equations were developed to predict aboveground stand level biomass in log products and harvest residue from routinely measured or predicted stand variables for Pinus radiata plantations in New South Wales,*** plantations were managed under three thinning regimes or stand types before clear-felling at rotation age by cut-to-length harvesters to produce sawlogs and *** residue material following a clear-fell operation mainly consisted of stumps,branches and treetops,short off-cut and waste sections due to stem deformity,defects,damage and *** system of equations did not include dummy variables for stand types in the model specification and was intended for more general use in plantations where stand density management regimes were not the same as the stand types in our *** other system that incorporated dummy variables was for stand type-specific *** systems of equations were estimated using 61 plot-based estimates of biomass in commercial logs and residue components that were derived from systems of equations developed in situ for predicting the product and residue biomass of individual *** cater for all practical applications,two sets of parameters were estimated for each system of equations for predicting component and total aboveground stand biomass in fresh and dry weight *** two sets of parameters for the system of equations without dummy variables were jointly estimated to improve statistical efficiency in parameter *** predictive performances of the two systems of equations were benchmarked through a leave-one-plot-out cross validation *** were generally superior to the performance of an alternative two-stage approach that combined an additive system for major components with an allocative system for *** using forest harvest residue biomass for bioenergy has increasingly become an integrated part of forestry,reliable estimates of pro

关键词： Plot-based biomass estimates Wood product Harvest residue bioenergy Systems of additive and allocative equations Prediction error variance functions

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Early performance of Pinus radiata provenances in the earthquakeravaged dry river valley area of Sichuan, southwest China

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Journal of Forestry Research 2013年第4期24卷 619-632页

作者： huiquan bi Rongwei Li Zongxing Wu Quan Huang Qianli Liu Yongli Zhou Yun Li Forest Science Centre New South Wales Department of Primary Industries School of Forest and Ecosystem Science University of Melbourne Sichuan Forestry Academy Aba Forest Research Institute 71 Jiaochang Street School of Information Science and Technology Beijing Forestry University

A provenance experiment involving five native provenances and an Australian landrace of Pinus radiata （D. Don） was established over three sites in the dry river valley area of Sichuan, southwest China in 2004 in order to select the most suitable provenance for environmental planting on the dry, steep and degraded slopes to reduce soil erosion. Although with much lower soil moisture supply and mean minimum temperatures in winter compared to P. radiata provenance trials estab- lished elsewhere in the world, these sites are within the working limits of the species defined by previous climate modelling and matching. Be- cause of the difficult site conditions and severe natural disturbances after the experiment was established, mortality was high across the three sites in comparison to provenance trials in other countries.

关键词： Pinus radiata, dryland provenance performance multilevellinear mixed models repeated measures analysis

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新南威尔士州东南台地的高桉异龄次生林收获量方程的研究

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桉树科技 1997年第1期14卷 49-60页

作者： huiquan bi vic Jurskis 朱日光新南威尔士州林业局研究开发处

采伐后保留的老树使次生林分的生长不整齐。在澳大利亚,林场经理十分需要知道这种林分的生长和产量信息。在新南威尔士州东南台地的高桉(***)异龄次生林分中随机收集了30块样地资料,推导出了与老树密度有关的次生林分收获量方程。收获... 详细信息

采伐后保留的老树使次生林分的生长不整齐。在澳大利亚,林场经理十分需要知道这种林分的生长和产量信息。在新南威尔士州东南台地的高桉(***)异龄次生林分中随机收集了30块样地资料,推导出了与老树密度有关的次生林分收获量方程。收获量方程的预测结果是,如果没有任何老树,在最好的立地条件上,异龄次生椿分蓄积量从20年时的253m^3/hm^2能长到80年时的623m^3/hm^2;在一般立地条件下,可从253m^3/hm^2长到339m^3/hm^2;而在较差的立地条件下则可从84m^2/hm^2长到206m^3/hm^2。如果保留的老树密度从0～100株/hm^2,次生林分的蓄积量的百分比则减少0～66％。由于过去的森林大火和采伐的影响,老树的树冠大小范围较大,许多树冠较小而且稀少,但又不是原来的健康树冠。在应用本收获量方程之前,必须对老树的含义有一个清楚的了解,否则次生林分的蓄积量的预测会出现误差。

关键词：桉树异龄次生林收获量

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Survey of damaging pests and preliminary assessment of forest health risks to the long term success of Pinus radiata introduction in Sichuan, southwest China

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Journal of Forestry Research 2008年第2期19卷 85-100页

作者：李荣伟肖育贵周建华吴宗兴阎红黄泉刘千里四川省林业科学研究院四川省成都市610081 中国林业科学研究院北京100091 阿坝州科学技术研究院四川省汶川县623000

Pinus radiata was introduced to the summer rainfall environments of Sichuan Province, China in the 1990s as a part of an afforestation pmgram for soil and water conservation in the arid and semi-arid river valley area of Aba Prefecture. Within this region a total area of 26 000 ha have been identified through climate matching as suitable and a further 63 000 ha potentially suitable for environmental plantings of P. radiata. The plantations are being established in widely separated small patches on steep and degraded slopes along the dry river valley The newly introduced P. radiata are exposed to two kinds of forest health risks： they may be attacked by （a） indigenous pathogens and pests against which they may not possess any resistance or （b） by inadvertently introduced foreign pests or pathogens. This paper presents a survey of the potential damaging pests and a preliminary assessment of forest health risks facing the P. radiata plantations over a much longer timeframe than the initial phase of introduction and early plantation establishment. An empirical appmach was adopted to evaluate forest health risks by a combination of literature review, examination of historical records of pest and disease outbreaks in the surrounding conifemus forests, field surveys and inspections, specimen collection and identification, and most importantly, expert analysis of the likelihood of attack by specific pests and pathogens and the subsequent impact of such attacks. The assessment identified some specific forest health risks to the long-term success of P. radiata introduction in this area. These risks are closely associated with the indigenous pests and pathogens of the two native pine species, P. tabulaeformis and P. armondii since these pests and pathogens are considered more likely to establish on P. radiata over time. Exotic pests and pathogens are of a quarantine concern at present. Based on the results of assessment, recommendations are pmvided to improve forest vigour and

关键词： Pinus radiata species introduction dry river valley forest health risks

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