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Table of Content

    28 February 2021, Issue 1
    Integrated Management and Administration
    Practice and Innovation of Forest Administrator System in Anqing City of Anhui Province
    TANG Xiaoping, LUO Min, HUANG Guosheng, SHI Liuxi, DANG Yongfeng, WANG Wei
    2021,(1):  1-10.  doi:10.13466/j.cnki.lyzygl.2021.01.001
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    Forest administrator system is an important and innovative system to implement the territorial responsibility,improve the long-term mechanism,enhance the ecological management system and improve the management ability.Anqing city of Anhui Province is located in the Dabie Mountainnational key ecological function area and the Yangtze Plain Lake cluster distribution area,and the ecological location is important.In order to speed up the construction of ecological civilization,promote the realization of the value of ecological products and upgrade the modernization of forestry governance capacity,Anqing has established a system with the Party and government leadership responsibility system as the core and set up the operating mechanism of the forest administrator system,including the scientific planning of the objectives and tasks,the systematic construction of the organizational structure,the innovative design of the operating mechanism,the regular implementation of the assessment and evaluation and the full implementation of the smart service.Remarkable achievements have been made in maintaining the ecological red line,expanding the ecological space,managing and controlling the ecological risks,innovating the governance mechanism and benefiting the social forest farmers.At the same time,with the aim to solve existing problems,this paper puts forward some countermeasures and suggestions for constructing the long-term mechanism of the forest administrator system: the forest administrator system should be systematic,making overall plans for the systematic management of mountains,rivers,forests,fields,lakes and grasses,and promoting its development from "effective" to "long-term effective ",from "forest administrator system" to "long-term forest management".The forest administrator system should focus on the ways to realize the value of ecological products.

    Practice and Enlightenment of the Central and Local Cooperation to Build National Reserve Forest Project—Take the Chongqing National Reserve Forest Project as an example
    LUO Lian
    2021,(1):  11-16.  doi:10.13466/j.cnki.lyzygl.2021.01.002
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    The implementation of the national reserve forest project is a vivid practice of the concept that lucid waters and lush mountains are invaluable assets.It is an important way to maintain national ecological security and a vital opportunity for the forestry industry to go through transformation and upgrading to high-quality development.The construction of the national reserve forest requires a large amount of funds,but the traditional financial investment is far from meeting the demand.The government is expected to encourage market entities to use development and policy capital to build the national reserve forest.This paper tries to analyze the the central and local cooperation in building national reserve forests in recent years,and based on the research on the innovation mechanism of the national reserve forest project in Chongqing,policy suggestions focusing on public welfare,people's livelihood and innovation are proposed to improve relevant industry policies.

    Discussion on Operation and Development of State-owned Forest Farms in Western Region of Inner Mongolia
    QIN Jiawei, YU Baole
    2021,(1):  17-22.  doi:10.13466/j.cnki.lyzygl.2021.01.003
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    State-owned forest farms,which are an important component and supportof the ecological security in China,play a key role in forestry ecology construction in Inner Mongolia.State-owned forest farms are also of the significance in implementing the construction of ecological civilization and practicing the idea that lucid waters and lush mountains are invaluable assets.Based on the thorough understanding of the operation of state-owned forest farms in six cities in the western region of Inner Mongolia,this paper summarizes the characteristics of state-owned forest farms,analyzes major difficulties faced by state-owned forest farms,discusses ways of solution and puts forward reasonable suggestions for the future development of state-owned forest farms.

    Analysis on Development of Forest Cities in Yunnan Province
    PENG Jiansong, ZHU Kun, XV Hui, HUANG Xiaoyuan, DAI Jiping, HUANG Ruijin
    2021,(1):  23-29.  doi:10.13466/j.cnki.lyzygl.2021.01.004
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    Forest city is an important carrier of urban ecological civilization construction.This study attempts to analyze the current situation and gap of forest city construction in Yunnan Province and define the development goal of forest cities in the province.By evaluating the development potential of forest cities in 16 prefectures(prefectures,cities) and 129 counties(cities,districts) in the province,the study analyzes the current situation and problems of each region and tries to construct the development layout of Yunnan plateau mountain forest cities featuring "five regions,four belts and three groups".Combined with the advanced experience of forest city construction in China and the actual situation of Yunnan Province,the development methods of forest city are put forward in order to provide the basis for the construction of forest city in Yunnan plateau mountainous area.

    Discussion on Forestry Engineering Projects and its Fund Management Mechanism in China
    LI Wanli
    2021,(1):  30-36.  doi:10.13466/j.cnki.lyzygl.2021.01.005
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    Based on the actual situation of China's forest industry,this paper tries to propose the concept of forest owner and innovative ideas on forestry project management mechanism.It tries to put forward improvement measures for forest projects and its fund management,including updating project planning concept,improving project planning and design,reforming project and fund management system and encouraging forest owners,in a bid to provide assistance to the construction of forestry engineering projects and fund management.

    Discussion on REITs applied in Forestry Financing
    CHEN Boyu
    2021,(1):  37-43.  doi:10.13466/j.cnki.lyzygl.2021.01.006
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    With the development of the Chinese forestry industry and the acceleration of ecological restoration projects,the gap between forestry capital investment and demand is growing.The problems between forestry investment and financing mechanisms have become increasingly prominent,which is a major obstacle to the further development of forestry in China.Real estate investment trusts(REITs),as financial products with high liquidity,low investment risk and relatively stable returns,can revitalize the assets,broaden social capital investment channels and enable the capital market to efficiently serve the real economy.New regulations on REITs were intensively introduced since April 2020,which marks the official start of real estate trust fund pilot projects in China.Since the release of the policy,major fund companies have been actively looking for high-quality projects.As of November 2020,several fund companies planning for IPO of REITs have reported to the National Development and Reform Commission,China's top economic planner.A large number of REITs products will be available soon.As a result,a new blue ocean is about to emerge.However,due to the current requirements,forestry projects do not yet have the conditions for the large-scale public offering of REITs.To provide enlightenment and policy recommendations for further broadening the financing channels of China's forestry and reducing financing costs,this study,from the perspective of the capital market,studies the feasibility and necessity of using REITs for forestry industry financing by analyzing the characteristics of REITs products and the financing dilemma and development trend of the Chinese forestry industry.

    Research on the Current Status and Countermeasures of Joint Prevention and Control Mechanism of Forest Pests in China
    LU Xiuliang, QIU Lixin, GAO Liang, LIN Xiao, WEN Xuanye, CHANG Guobin
    2021,(1):  44-49.  doi:10.13466/j.cnki.lyzygl.2021.01.007
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    Joint prevention and control mechanism is an important emergency management organization system,which plays an important role in the prevention and control of forest pests.This paper attempts to analyze current status and major problems of the joint prevention and control mechanism of forest pests and summarize construction experience of the joint prevention and control mechanism in other fields in China.It puts forward countermeasures and suggestions for the mechanism in light of four aspects:to strengthen the organization and leadership,to increase support for key regions,to intensify target management and to improve the projects' reserve system.This paper aims to offer reference for promoting the sound development of the joint prevention and control mechanism.

    Scientific Research
    Estimation on Forest Above-Ground Biomass Based on Simulated Large-Footprint LiDAR and Multi-Layer Perceptron
    XV Changjian, LIU Yingchun, ZUO Lijun, LI Jiangeng, ZHANG Ting, HAN Lumeng, FANG Yu, ZHANG Yin, WANG Tian
    2021,(1):  50-60.  doi:10.13466/j.cnki.lyzygl.2021.01.008
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    Forests are important global terrestrial ecosystems.Sample survey is a commonly used method by countries to assess their forest resources and biomass.With the development of LiDAR technology,spaceborne large-footprint ladar become an option to estimate forest above-ground biomass(AGB) in large areas.In order to develop the method to estimate forest AGB with large-footprint LiDAR,the study proposes an AGB estimation model based on simulated large-footprint LiDAR and multi-layer perceptron.Based on 13 groups of LiDAR waveform parameters,the multi-layer perceptron achieves higher accuracy than multiple linear regression to estimate AGB.Compared with the field measured AGB,the deviation range of the estimated AGB from the multiple linear regression is between -34.96 to 23.28 t/hm2 and the estimated deviation of the multi-layer perceptron is between -19.09 to 20.19 t/hm2.Therefore,multi-layer perceptron is better than multiple linear regression in estimating forest AGB.

    Research on LiDAR Stand Average High Inversion Method Based on Auto-adaptive Threshold and Peak Value
    WU Simin, SUN Hua, LIN Hui
    2021,(1):  61-68.  doi:10.13466/j.cnki.lyzygl.2021.01.009
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    With the increasing density of point cloud obtained by LiDAR,it is possible to extract the average height of stand at sample plot scale.However,the relation between the extraction accuracy of average height of stand at sample plot scale and tree species is still unclear,so a stand average height extraction method suitable for various tree species is urgently needed.This study tries to take the state-owned Gaofeng forest farm in Guangxi Zhuang Autonomous Region as an example and use the canopy height model(CHM) generated by airborne LiDAR point cloud data.Based on 201 sample plots data measured on the ground,the paper proposes a stand average height extraction algorithm combining auto-adaptive threshold and peak value and analyzes the influence of tree species on extraction accuracy.The results show that:1) the average high extraction accuracy of different tree species is different.The accuracy of Chinese fir is the highest,followed by Eucalyptus and other broad-leaved trees;2) The auto-adaptive threshold combined with peak value algorithm can extract the average stand height(R2=0.75,RMSE=3.11 m,rRMSE=22.07%),and has strong robustness for different tree species;3) The sensitivity of broad-leaved and coniferous species to different extraction methods is different.The average stand height extracted in this study can be used as the basis and reference for the inversion of forest volume and biomass.

    Research on Estimation of Coniferous Forest Volume in Longnan County Based on Landsat 8 and PALSAR-2 Images
    LUO Kaijian, XV Xiaodong, LONG Jiangping, XV Congrong, LIN Hui, HE Xiaofeng
    2021,(1):  69-76.  doi:10.13466/j.cnki.lyzygl.2021.01.010
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    Forest stand volume estimation is an important research field of forestry remote sensing.Factors such as cloud and fog weather and spectral saturation have restricted the accuracy of optical remote sensing image estimation.Synthetic Aperture Radar(SAR) images have the characteristics of strong penetrability and are less likely to be affected by cloud and fog,which make up for the deficiencies of optical remote sensing.This study uses the coniferous forest in Longnan county,Jiangxi Province as the study area,combines Landsat 8 and PALSAR-2 dual-polarization SAR image data to extract a total of 245 remote sensing factors such as spectral information,vegetation index,texture information and backscattering coefficient based on remote sensing data preprocessing.Based on the Pearson correlation coefficient method and the multiple stepwise regression method,65 remote sensing factors are selected for the estimation of stand stock.Taking forest stand canopy closure as a stratification factor,the study adopts five models of linear,KNN,support vector machine(SVM),multi-perceptron(MLP) and random forest(RF) to estimate the forest stand volume,and tests the accuracy of the estimated results.The experimental results show that:1) Compared with using the spectrum and texture information of Landsat8 alone,the backscatter information of PALSAR-2 based on the canopy closure classification and fusion significantly improves the inversion accuracy of accumulation 2) In low canopy closure forest stand,the linear model has the highest accuracy(rRMSE=21.16%),in medium canopy closed forest stand,the MLP model has the best estimation effect(rRMSE=30.61%),in high canopy closure forest stand,the MLP model has the best estimation effect(rRMSE=27.53%).Based on the backscattering coefficient of PALSAR-2,the canopy closure stratification can effectively improve the inversion accuracy of the medium and high accumulation areas.

    Estimation on Forest Volume Based on ALS Data and Dummy Variable Technology
    JIN Jing, YUE Cairong, LI Chungan, GU Lei, LUO Hongbin, ZHU Bodong
    2021,(1):  77-85.  doi:10.13466/j.cnki.lyzygl.2021.01.011
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    Based on the airborne LiDAR data,the influence of dummy variables on the estimation accuracy of stand volume is analyzed.In this study,Guangxi Gaofeng Forest Farm is taken as the research object,and based on the airborne lidar point cloud data and 96 plot data,the plot data is randomly divided into training samples and test samples are at a ratio of 7∶3.The samples and the corresponding point cloud features are estimated by regression modeling through the use of random forest model(RFR) and support vector machine model(SVR),and the tree species group(coniferous forest and broad-leaved forest) and age group as dummy variables are introduced into the regression model.The study uses the estimation accuracy of the test samples to evaluate the estimation accuracy of the model,and introduces tree species group as dummy variables.The RFR determination coefficient R2 increases from 0.59 to 0.64,and the SVR determination coefficient R 2 increases from 0.49 to 0.50.With the introduction of dummy variables in the age group,the RFR determination coefficient R 2 increases from 0.59 to 0.65 and the SVR determination coefficient R 2 increases from 0.45 to 0.55.According to the modeling accuracy and verification accuracy results of the model,the introduction of dummy variables is relatively effective in improving the accuracy of the accumulation estimation model.The dummy variables of age group have better effect on model accuracy improvement than dummy variables of tree species group.

    Comparison of Chlorophyll Fluorescence Characteristics Between Torreya jiulongshanensis Leaves and its Widespread Congener T.Grandis
    ZHENG Yingmao, ZHOU Yuhong, PAN Chengchun, LIU Julian, LAN Benkuan, KANG Huajing
    2021,(1):  86-93.  doi:10.13466/j.cnki.lyzygl.2021.01.012
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    In order to provide scientific basis for the conservation of Torreya jiulongshanensis germplasm resources,response of chlorophyll fluorescence parameters of T.jiulongshanensis(male and female) and its widespread congener T.grandis leaves(under cultivation and field conditions,respectively) to light intensity are compared in this paper.The results show that,under cultivation conditions,the maximum fluorescence value of photosystem I of female seedlings of T.jiulongshanensis is higher than that of male seedlings and T.grandis.The light saturation points of female and male seedlings of T.jiulongshanensis are 788.581 and 550.640 μmol/(m2·s),respectively,and the corresponding maximum electron transfer rates are 40.690 and 39.546 μmol/(m2·s),respectively.Similarly,under field conditions,the light saturation points of female and male plants of T.jiulongshanensis are significantly higher than those of T.grandis,which stand at 1 165.361 and 1 416.817 μmol/(m2·s),respectively.The maximum electron transfer rate of photosystem II of female plants of T.jiulongshanensis is the highest,which is 80.322 μmol/(m2·s).Therefore,T.jiulongshanensis is a sunny tree species and has stronger photosynthetic potential than T.grandis.

    Study on Lasso-gray Prediction Model of Pecans Yield in Lin 'an
    FENG Yazhi, HU Yanrong, LIU Hongjiu
    2021,(1):  94-102.  doi:10.13466/j.cnki.lyzygl.2021.01.013
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    In order to make accurate prediction on pecan yield,this paper takes Lin 'an pecan as an example for empirical study and analyzes the influential factors such as the climate and the planting quantity through establishing the Lasso regression and gray prediction combination model.The results show that compared with the prediction effects of the three models,Lasso-BP,Lasso-RBF and Lasso-GRNN,the prediction accuracy of the Lasso-GM model is higher,with an average relative error of 6.99 percent,from which the law of the changes of pecans output can be mastered.Meanwhile,the prediction results also show that by 2024,the output of Lin 'an pecans will continue to increase in a stable way.

    Analysis on Changes of Landscape Connectivity in Nabanhe Nature Reserve
    SHEN Run, SHI Zhengtao, HE Guangxiong, LIN Yanhua
    2021,(1):  103-110.  doi:10.13466/j.cnki.lyzygl.2021.01.014
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    Nature reserves are important foundations for the protection of species,but frequent human activities cause the fragmentation of biological habitat patches in nature reserves.The quantitative evaluation of landscape connectivity plays an important role in the protection of biological habitats.This article takes Nabanhe Nature Reserve as the study area.Based on high spatial resolution remote sensing data in 2014 and 2018,the index method of graph theory is used to analyze the change of the landscape connectivity index of the habitat and changes of the landscape and connectivity driving factors in the protected area.The results are as follows:1) In the landscape connectivity index,the integral index of connectivity(IIC) and probability of connectivity(PC) both show a downward trend as IIC and PC index decrease by 0.29 and 0.53,respectively,from 2014 to 2018,indicating that habitat patch fragmentation has increased in the reserve;2) The importance index of the largest patch decreases from 85.14 to 84.19.The temporal and spatial changes of the top ten importance patches indicate that the area of habitat patches has been decreasing in the nature reserve,with significant fragmentation in the central and central-western regions;3) Land use changes has an important impact on the landscape connectivity of the protected area.The increased use of four types of land such as rubber forests,farmland,reservoir and tea gardens are the driving force for habitat fragmentation.The results will provide a scientific basis for habitat protection in Nabanhe Nature Reserve.

    Evaluation on Urban Residents' Perception of Greenway Soundscape
    BIAN Jiayu, LENG Jiahui, ZHAO Zheng, WANG Yanbin
    2021,(1):  111-120.  doi:10.13466/j.cnki.lyzygl.2021.01.015
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    Based on a questionnaire survey of 512 respondents interviewed within the urban area of Shanghai in 2020,the study takes the Lujiazui section of the Huangpu riverside in Shanghai as an example,trying to evaluate the residents' perception of the urban greenway soundscape and discuss their preferences and potential influential factors.The study area involves three typical greenway types:natural,built and mixed type.The results show that residents' preferences for urban greenways will reflect a trade-off relation between the natural environment and man-made environment,and will be affected by many factors,which include not only differences in citizen perception caused by greenway soundscape differences,but also selective difference caused by individual heterogeneity of residents.The results of this study will provide reference and basis for the construction of urban greenways with more practical value and natural ecological benefits.

    Analysis on Forest Vegetational Cover Changes in Yuxi and its Driving Force
    ZHU Hongqin, WANG Jingwen, XV Yanhong, QI juncheng, LUO Hang, PENG Zexi
    2021,(1):  121-131.  doi:10.13466/j.cnki.lyzygl.2021.01.016
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    Forest covers can reflect the health of the forest ecosystem and space-time change is the basis for estimating the direction of the forest ecosystem development.This study attempts to analyze the change of time and space pattern of forest vegetational cover in Yuxi,Southwest China's Yunnan Province,from 2010 to 2019,and establish the regression model by single-factor and multi-regression analysis methods,respectively,to explore the drivers for the improvement and degradation of vegetational covers.The results show that the forest vegetational cover show a good trend and the factors and slope are not simple linear relationship.The study finds that the improvement rate of road and residential areas and forest vegetational cover are negatively related and positively related to the rate of degradation.Moreover,DEM,slope,large water body,public welfare forest management and forest cover improvement rate are positively correlated with the degradation rate and the slope direction is positively correlated with the improvement rate of stand vegetational covers,and the topographic fluctuation degree is negatively correlated with the degradation rate of stand vegetation cover.The driving forces for the improvement and degradation of forest vegetational covers are not the same and the influence mechanism is also different,which provides a scientific basis for better formulaing ecological protection policies.

    Comprehensive Evaluation of Soil Nutrients after Mixed Transformation of Pinus Sylvestris var.Mngolica Plantation
    SHI Liang, ZHANG Risheng
    2021,(1):  132-139.  doi:10.13466/j.cnki.lyzygl.2021.01.017
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    In order to explore the influence mechanism of different mixed models on soil nutrients,a 38-year-old Pinus sylvestris var.mongolica plantation is selected as the research object.After zonal thinning,Pinus sylvestris var.mongolica,Populus alba and Acer mono are planted in the thinning zone to form a mixed forest.Canonical correspondence and principal component analysis are used to compare the differences and corresponding relationships of soil chemical properties and enzyme activities in mixed forest.The results showed that the soil chemical properties after mixed transformation are higher than those of the control,and the contents of organic matter and available nitrogen in the plots of P.sylvestris var.mongolica×Acer mono(PAM2) and P.sylvestris var.mongolica×Populus alba(PPM2) were the highest,which were 14.74 g/kg and 49.63 mg/kg,respectively,but the content of available phosphorus is lower than that of P.sylvestris var.mongolica×P.sylvestris var.mongolica plots.Compared with the control,the soil enzyme activities of all plots are increased to varying degrees,and the soil enzyme activities of P.sylvestris var.mongolica×Populus alba are the best.In general,the comprehensive score of soil nutrient factors in the mixed sample plot is higher than that of the control,and that of the coniferous broad-leaved mixed forest is generally higher than that of the uneven aged Pinus sylvestris var.mongolica.Therefore,the construction of mixed forest is an effective way to improve soil ecology of Pinus sylvestris var.mongolica plantation in Horqin sandy land and prolong the life cycle of protective forest.

    Analysis of Trace Element in Soil of Gully, Pond and Meadow in Forest Steppe
    PENG Xujian, CHEN Pengfei, WANG Baijie, ZHANG Heng
    2021,(1):  140-146.  doi:10.13466/j.cnki.lyzygl.2021.01.018
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    In order to study the soil stoichiometric characteristics of swamp meadow in different slope directions and different depths in the forest-steppe ecotone,gully,pond and meadow in Arxan City,Inner Mongolia were taken as research areas,the contents of available trace elements(Fe,Mn,Cu,Zn) and organic C,total N,total P in different depth soil layers of shady slope and sunny slope were compared and analyzed through field investigation and indoor experiment.The results show that:1) The contents of available Fe and available Mn in shady slope and sunny slope soil first increased and then decreased with the increase of soil depth,and the difference of available Cu content was not significant with the change of soil depth.2) The contents of available trace elements in the soil showed the trend of Fe > Mn > Zn > Cu.3) There was no correlation between the contents of available trace elements and pH value,but the contents of available Fe,available Mn and available Cu.The correlation of available Zn content(P<0.01) was significant.4) There was no significant difference in C:N,N:P in different depth soil layers of the same slope aspect,but there was significant difference in C:P.5) There was no significant difference in soil pH in different depth soil layers of different slope aspect.The results of this study provide data support for the analysis of trace elements in the soil of ditches,ponds and meadows.

    Technical Application
    Developing Aerial Stand Volume Tables Based on Laser Scanning Data for Forest Region of Northeast China
    ZENG Weisheng, SUN Xiangnan, WANG Liuru, WANG Wei, PU Ying
    2021,(1):  147-155.  doi:10.13466/j.cnki.lyzygl.2021.01.019
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    Based on the airborne laser scanning(ALS) data and field measurement data of 1 947 sample plots distributed across the spruce & fir(Picea spp.& Abies spp.),larch(Larix spp.),Mongolian scotch pine(Pinus sylvestris var mongolica),Korean pine(Pinus koraiensis),oak(Quercus spp.),birch(Betula spp.),poplar(Populus spp.),elm(Ulmus spp.),linden(Tilia spp.),and other three precious broadleaved species(Fraxinus mandshurica,Juglans mandshurica & Phellodendron amurense) forest stands in Northeast China,the stand volume regression models were developed through multiple linear regression and nonlinear regression methods,and the base regression model was determined with comparison and analysis.Then,the integrated stand volume models with stand type-specific parameters and the same ALS variables were developed,using the dummy variable modeling approach.The results showed that multiple linear volume regression models developed in this study for the 10 stand types have 2~7 explainable variables and the coefficients of determination(R 2) are between 0.460~0.858;and the nonlinear models have 2~4 explainable variables and the R 2 are between 0.461~0.846.The two-variable nonlinear volume models based on mean height and mean intensity of point clouds are defined as standard volume models,of which the R 2 are between 0.440~0.815,the mean prediction errors(MPEs) are between 2.88%~4.42%,and the mean percent standard errors(MPSEs) are between 16.76%~25.52%,which almost meet the need for precision requirements of the regulation on forest management inventory.According to the stand volume models developed in this study for 10 forest types,aerial stand volume tables based on ALS data can be established,which may be applied in forest management inventory.

    Construction of Difference Site Index Model for Larix Principis-rupprechtii Plantation
    WANG Zhibo, JI Meng, LI Yongle, LI Yinxiang, MA Shiming, ZHANG Haidong
    2021,(1):  156-163.  doi:10.13466/j.cnki.lyzygl.2021.01.020
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    In the paper,the Larix principis-rupprechtii plantation in Sumu Mountain forest farm of Yin Mountain was taken as the research object.Based on the data of 43 analytic trees,the difference site index models were constructed based on Richards equation.The results showed that the difference model fitting results were significantly better than the basic model,with R2 above 0.96,RMSE between 0.86 and 0.96,and MAE below 0.42.The model derived by ADA method,the fitting result with b or c as free parameter is better than that with a as free parameter.In the model derived by GADA method,it is more reasonable to assume a linear relationship between the free a parameter and the variable X0.Through such methods as statistical analysis,residual analysis and site index curve cluster comparison,by applying GADA method,the difference model derived by free parameters $a=e^{X_{0}}$,$c=c_{1}+c_{2} X_{0}$ is the best model,which meets the requirements of biology and statistics.Higher site index has the greater extreme value of tree height and annual growth of dominant trees,and the earlier the curve reaches the inflection point.The results can provide basis for the scientific evaluation of site quality of Larix principis-rupprechtii plantation.

    Study on the Extraction of Individual Tree Height Based on UAV Visual Spectrum Remote Sensing
    BAI Mingxiong, ZHANG Chao, CHEN Qi, WANG Juan, LI Huayu, SHI Xiaorong, TIAN Xianyun, ZHANG Yuwei
    2021,(1):  164-172.  doi:10.13466/j.cnki.lyzygl.2021.01.021
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    The feasibility of using the watershed segmentation algorithm to extract tree height based on the canopy height model(CHM) generated by high-resolution imagery of UAV was discussed.Tree height data were obtained from Pinus yunnanensis Franch in Fuming County of Yunnan Province.Remote sensing imagery in the study area of the near ground was obtained through the DJI Phantom 4 Pro drone remote sensing system.Pix4D Mapper software was used to preprocess UAV images and reconstruct the research area in three dimensions and 3D point cloud.LiDAR360 software was used to process 3D point cloud and build a DSM(Digital Surface Model),DEM(Digital elevation Model)and CHM were generated.Then,for different canopy density of CHM,the watershed segmentation algorithm was used to divide and extract tree height.The accuracies of the results were elevated.Results showed that CHM could be accurately divided by the watershed segmentation algorithm and it was feasible that UAV imagery was used to extract the height of Pinus yunnanensis Franch.The comparative analysis of the data on the height of trees acquired from the UAV image and the field measurement shows that the R 2,RMSE,rRMSE is 0.893,1.23m,12.42%.At the same time,the measurement of tree height was affected by canopy density with the R2 and root mean squared error(RMSE)value for the least density being R2=0.939,RMSE=1.097m,for the next one was R2=0.921,RMSE=0.896m,and for the largest was R2=0.857,RMSE=1.450m.The accuracy of the measured height of the larger density was higher than that of the smaller density.

    Research on Crown Extraction Based on Improved Faster R-CNN Model
    HUANG Yanxiao, FANG Luming, HUANG Siqi, GAO Haili, YANG Laibang, LOU Xiongwei
    2021,(1):  173-179.  doi:10.13466/j.cnki.lyzygl.2021.01.022
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    Canopy information is an important part of forest resources investigation.The traditional method of crown width measurement is through field survey,which may result in a significant error in the specific terrain and forest environment,along with great labor force,cumbersome and time-consuming operation procedure.The development of UAV imaging technology and machine learning provides a new method and realization idea for crown measurement.This paper employed UAV to obtain the orthophoto images of two pure Metasequoia glyptostroboides in the greenway of Qingshanhu in the east of Lin'an District.An advanced object detection method,Faster R-CNN,was improved to recognize the tree crown and extract the crown width.The Accuracy and R 2 of the improved Faster R-CNN model are 92.92% and 0.84 respectively,which are 5.31% and 0.12 higher than those of the original model.This shows that the UAV and object detection technology are feasible to identify the tree crown.Compared with the traditional survey method,it has the advantages of high efficiency,convenience and low cost.

    Method for Sub-compartment Investigation Factors Setting and Information Acquisition Based on Integrated Aerial-Space-Ground Forest Inventory System
    DAI Huabing, LI Chungan, PANG Yong, LI Chonggui
    2021,(1):  180-188.  doi:10.13466/j.cnki.lyzygl.2021.01.023
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    In order to solve the problems in the current forest resources planning,design and forest inventory,a novel technology system of integrated aerial-space-ground forest resources survey and monitoring system was proposed and tested.This paper introduced the method for forest sub-compartment investigation factors setting and information acquisition.Compared with the traditional methods,this method lacks some factors which need to be recorded in the field,such as understory vegetation,natural regeneration and forest health status.However,the sub-compartment investigation factors of the novel technology system could still reflect the forest land and tree status(type,quantity,quality and structure),as well as the natural environment conditions.It can completely satisfied the requirements of forest resources management and statistics of forest resources reports in collective forest areas,and it also can meet the demands of various related applications for the basic data of forest resources.The basic attributes of sub-compartment(land type,dominant tree species,tree origin and associated tree species) need remotely sensed image interpretation and some supplementary field investigation,while the other attributes of sub-compartment can be obtained automatically by computer program.This method greatly reduces the investigation workload and labor force,while improves the efficiency and quality.The results indicated that it can effectively ensure the reliability of sub-compartment investigation data and the quality of forest resources inventory results.

    Short Term Effects of Compound and Phosphate Fertilizer on the Growth of Juvenile Pinus Yunnanensis Plantation
    FU Zhigao, LI Lianfang
    2021,(1):  189-196.  doi:10.13466/j.cnki.lyzygl.2021.01.024
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    In order to understand the short-term(one year after fertilization) growth effects of compound fertilizer(including slow- release fertilizer,SRF) and phosphate(P) fertilizer on a 12-year-old Pinus yunnanensis plantation,the L9(3 4) orthogonal design was employed to implement the trial.At one year after fertilization,the growth rates of diameters at breast height(DBHs),tree height(THs) and individual tree volumes(ITVs) of treatment combinations(TCs) were 4.29%~12.37%,7.96%~22.58% and 20.13%~38.39%,while numbers of control were 3.80%,10.21% and 15.76%,respectively,which was of significant difference between the TCs(P<0.01).The dominant factor affecting growth rate of the DBH was the type of fertilizer,while which of the TH and ITV was the amount of the P fertilizer.The growth rates of the THs went up with the increase of P fertilizer application,while DBH was opposite.The interaction of fertilizer types and P fertilizer amount had significant difference effects on the DBH and TH growth rates(P<0.01 or P<0.05).The demand of nutrient types and quantity for the DBH and TH growth of juvenile P.yunnanensis was different,and the fertilization of the forest primarily focuses on promoting the DBH growth.Suitable types of compound fertilizer and P fertilizer amount could significantly improve the growth of trees.Accurate fertilization could be achieved by taking every 5cm diameter of the DBH as the calculation unit of fertilization.The combination of the 0.75 and 0.50 kg/5 cm of 9-month SRF and diammonium phosphate could promote the growth of juvenile P.yunnanensis plantation and increase the stand volume in a short period of one year after fertilization based on comprehensive results of the optimal combination of theory and practice,the interaction results of compound fertilizer types and P fertilization amount,and the dominant factors affecting the timber volume of the stand.

    Forest Biomass Investigation Design Using Stratified Sampling in Simao District
    WANG Rui, YANG Qinyu, OU Guanglong, XU Hui
    2021,(1):  197-202.  doi:10.13466/j.cnki.lyzygl.2021.01.025
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    Based on the second class survey data of forest resources in Simao District of Pu'er City,taking forest origin,land type,age group and dominant tree species as stratified variables,the forest biomass was estimated by stratified sampling with 95%,90% and 85% sampling design accuracy under 95% reliability.The results show that:1) stratified sampling has obvious advantages of small sample size and high sampling accuracy.In Simao District of Pu'er City,the efficiency of stratified sampling based on dominant tree species is about 52% higher than that of systematic sampling with 85% design accuracy;2) stratified sampling based on single variable has significant advantages for dominant tree species.According to the design accuracy of 85%,the actual sampling accuracy can reach 87.82% under the premise of 44 samples.