Table of Content

28 August 2022, Issue 4

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Ecological Forum

Discussion on the Construction of National Forest and Grassland Fire Prevention Support System

ZOU Quancheng, LU Yuan, GUAN Zhen, PENG Lingli, CHAO Bixiao, BIAN Fei, CHEN Mengdi, MU Xiaowei, YAN Ping

2022,(4):  1-7.  doi:10.13466/j.cnki.lyzygl.2022.04.001

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Forest and grassland fire is listed by the United Nations as one of the eight natural disasters in the world,which not only severely damages forest resources and ecological environment,but also causes great harm to people's lives,property and public safety.China has a vast territory,and the task of forest and grassland fire prevention and control is arduous.Fire prevention has always been the top priority of forestry and prataculture.After the reform of the government institutions,National Forestry and Grassland Administration is mainly responsible for forest and grassland fire prevention,carrying out fire prevention patrols,fire source management,daily inspection,publicity and education,construction of fire prevention facilities,and organizing local forestry and grassland departments to deal with early fires.The major project construction plan for ecological protection and restoration support system is one of the nine special plans in the overall plan for the national major ecological system protection and restoration major project,clarifies that in enhancing the protection capacity of important ecological resources such as forests and grasslands.It is necessary to carry out the construction of forest and grassland fire prevention and extinguishment support systems,which provides a fundamental basis for forest and grassland fire prevention in the new era.By understanding and grasping the current situation of forest and grassland fire prevention work,this paper proposed thoughts on the construction of forest and grass fire prevention system,strengthening the early fire situation and improving the guarantee ability in the new era from the perspectives of climate,forest conditions,social conditions,and from the responsibility system,capacity building and other multi-scale.The system construction ideas provided a references for promoting the high-quality development of forest and grassland fire prevention work.

Ideas on Standardization Construction of GrasslandRoots Stations

CHENG Ziyue, MA Lan, JIA Xiaojun, ZHANG Miao

2022,(4):  8-12.  doi:10.13466/j.cnki.lyzygl.2022.04.002

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To explore the new ideas and new modes of the coordinated development of grassland ecological protection and scientific management in the new era,and to improve the practical needs of the scientific management ability and protection and restoration of the grass-roots grasslands,how to build a standardized grassland grass-roots stations were discussed.This paper put forward the idea of "system,team and facilities" based on new policies,new technologies and new ideas,so asto provide a valuable reference for the construction of grassland grass-roots stations and the innovation of grass-roots grassland management mechanism.

Scientific Research

A Study on Integration of Forest Stock Data at Different Levels in Forest Inventory and Monitoring

ZENG Weisheng, YANG Xueyun, SUN Xiangnan, LIU Qiangyi, ZHANG Yuchao

2022,(4):  13-19.  doi:10.13466/j.cnki.lyzygl.2022.04.003

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It is necessary to conduct national and local integrated forest resources inventory and monitoring,and implement decomposition of provincial forest stock data to prefecture,county,and township level,and even every forest stand polygon,for promoting the supervision and assessment of forest chief system at all levels.Based on the data of forest resources inventory and monitoring in recent years in Beijing,the procedure for implementing decomposition of forest stock data into all stand polygons was presented,where the amount of municipal forest stock was taken as the total for control,and forest volume prediction model and simultaneous models of three forest stocks (volume stock,biomass stock and carbon stock)were applied.Given the data of forest resources planning and designing inventory for reference,the joint estimation method could be adopted to adjust the data of prefecture and county level appropriately,while the errors of different data need to be considered as a whole.Through the establishment of forest volume prediction model and simultaneous models of three forest stocks in Beijing,the forest volume,biomass and carbon storage of Beijing in 2021 were decomposed to district,and township level and every forest stand polygon,realizing the integration of stock data at municipality,district and township level.It is showed that the method of applying modeling technology to decompose three forest stocks into forest stand polygons presented in this study is feasible in practice.

Study on Applicable Stand Form Height Models of Key State-Owned Forest Regions in Heilongjiang Province

BIAN Fei, WANG Hongchun

2022,(4):  20-27.  doi:10.13466/j.cnki.lyzygl.2022.04.004

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The modeling and evaluation methods of stand form height were studied in order to establish the stand form height models suitable for different stand types in key state-owned forest areas in Heilongjiang Province.Based on the data from 9974 sample plots,17 stand types were formed by classification,8 functions which covered all common stand form height models were selected for fitting,and the optimal models were determined by maximizing the adjusted coefficient determination (Ra²)and minimizing the standard error of estimate (SEE).Four essential evaluation indices including the total relative error (TRE),the mean systematic error (MSE),the mean prediction errors (MPE)and the mean percent standard errors (MPSE)were used to cross-verify the optimal models.Optimal models for 32 sub-regions were established.The further regression analysis showed that the TRE and the MSE were within ±0.1%,the MPE was less than 3% and the MPSE was less than 12%.The representative stand form height model system of Heilongjiang key state-owned forest region was formed.These results showed that the established optimal models had good compatibility with the corresponding sample plots,and the models had good predictability.This study made up for the vacancy of stand form height modeling in Heilongjiang key state-owned forest region,which had the value of popularization and could be applied in the forest managementinventory and in the continuous forest inventory.It was further verified that the method of model fitting by using all sample data and model verification by using jack-knife method was feasible.

Characteristics of Seed Rain and Soil Seed Bank in Broad Leaf and Chinese Fir Mixed Forest in Wuchao Mountain

JIAO Jiejie, LI Linghuan, WANG Jianmin, SUN Jiejie, WU Chuping, YAO Liangjin, WANG Zhigao, YUAN Weigao

2022,(4):  28-35.  doi:10.13466/j.cnki.lyzygl.2022.04.005

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In order to explore the succession mechanism of Chinese fir forests,three 40 m×40 m mixed fir and broad-leaved forests were set up in blocks with similar habitats,such as altitude,slope and aspect,in the mixed forest of fir and broadleaf that have been in natural succession for about 30 years in Wuchao Mountain,Hangzhou.In the sample plot,a seed rain collector was arranged in the sample plot for two years of collection,and the litter layer,0~5 cm humus layer and 5~10 cm soil layer were collected in a sampling area of 0.20 m×0.20 m,and then bagged and marked.75 samples were taken from each plot,in a total of 450 samples,and the seed germination experiment was carried out.Our results showed that there were nine species in the seed rain,of which Cunninghania lanceolata (seed rain density 12.91 seeds/m²)and Elaeocarpus(seed rain density 7.60 seeds/m²)were the main components,accounting for 94.16% of the total.The duration of C.lanceolata seed dispersal was 70 months,with two peaks in July and October,respectively.The duration of seed dispersal of Elaeocarpus was 4 months,with a peak in November to December.Seed of C.lanceolata and Elaeocarpus were also the main species in the soil seed bank.C.lanceolata seeds were mainly stored in the litter layer.In contrast,Elaeocarpus seeds were mainly stored in the 0~5cm soil layer.The seed density and germination rate of Elaeocarpus were 2~5 times higher than those of C.lanceolata.Moreover,the composition of non-dominant species in soil seed bank varied greatly from year to year.The retention of seeds in the litter layer resulted in low seed density in the C.lanceolata forest soil,which was the main reason for the difficulty of the natural regeneration of C.lanceolata.The results indicated that,broad-leaved species could regenerate via seeds in natural succession.

Evaluation on Structure and Stability of Quercus mongolica Forest Community in Xiaolong Mountains

JIANG Mengduo, MA Yingdong, JIANG Rui, DAI Xiaofen, LIU Jiancong, ZHAO Yaling

2022,(4):  36-44.  doi:10.13466/j.cnki.lyzygl.2022.04.006

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Quercus mongolica forest is the most typical secondary mixed forests in north of Xiaolong Mountains.Modern ecological approaches to forest structured management theory were applied to our study where four sample plots of 900m² were selected.Based on structural parameters including mixing(M),uniform angle index (W),neighborhood comparison(U),crowding (C)and diameter distribution,the community structure was analysed,and then the community stability was evaluated by π value method for stand optimal state,all of which aimed to understand this succession and structural characteristics of community,and further to provide scientific basis for natural forest cultivation and conservation.The results showed that the diameter class structure proved not to be a sheer inverted J shape,in which medium and small diameter of trees covering 6cm≤DBH≤12cm maintained stability of diameter class structure.The mingling of community was well,with mingling in highest intensity level accounting for 58.42% and that in higher intensity level accounting for 36.19%.65.46% of trees were in randomly distributed level,but they had not reached threshold value yet.Trees in weaker level for neighborhood comparison accounted for 25.13%,of which tree crown overlaped heavily and 45.17% of trees were in dense level for crowding.The community wasn't in optimal state because of maximum value in 0.66,thus the community was in stage of progressive succession.To maintain the development and stability of forest community,it needs to regulate the spatial structure,improve forest quality,and alleviate competition,so as to promote natural regeneration and recovery of mixed forest community.

Analysis on the Changing Tendency of Carbon Sequestration and Carbon Density of Natural Forests in Yunnan Province

HU Zhongyu, SU Jianlan, LONG Qin, LI Maomei

2022,(4):  45-53.  doi:10.13466/j.cnki.lyzygl.2022.04.007

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Based on the forest resources inventory data of eight times (1977-2018),the biomass expansion factor was used to analyze the carbon sequestration and carbon density of natural forests in Yunnan Province.The results showed that:1)The carbon sequestration of natural forests in Yunnan Province increased from 450.886 million tons in the second inventory to 810.151 million tons in the ninth inventory,with a net increase of 359.265 million tons and an annual growth rate of 1.64%;2)The carbon density of natural forest showed a "rising-falling-rising"trend,carbon density tested in the ninth inventory was 55.79t/hm²;3)In the seventh to ninth inventory,the total amount and increment of carbon sequestration in middle-age forest were the highest,and the order of carbon density in natural forest in the third inventory was overmature forest>mature forest>near mature forest>middle-age forest>young forest,the order of carbon sequestration of different forest species was shelterbelt forest>timber forest>special forest>fuel forest,and the order of carbon density was special forest>shelterbelt forest>timber forest>fuel forest;4)Among the different dominant tree species,Quercus,broadleaves mixed forest,Pinus yunnanensis,mixed coniferous and deciduous forests,other soft wood and Abies fabri were the main contributors to the carbon sequestration of natural forests in Yunnan Province,the order of carbon sequestration increment of different dominant tree species was:broadleaves mixed forest>mixed coniferous and deciduous forests>Pinus yunnanensis>mixed coniferous>Abies fabri,and the estimated carbon density of Tsuga chinensis, Abies fabri,Picea asperata was quite high,with sound growth quality.

Evaluation on Forest Biomass and Carbon Storage in Pearl River Delta in Guangdong Province

LI Kangjie, HU Zhongyue, LIU Ping, XU Zhengchun

2022,(4):  54-60.  doi:10.13466/j.cnki.lyzygl.2022.04.008

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Based on the data of the ninth continuous inventory of forest resources in Guangdong,the single-element diameter at breast height (DBH)model was used to calculate the biomass of arbor forest in the Pearl River Delta.The carbon storage per plant in the arbor forest was calculated by the carbon content coefficient of trees.The biomass and carbon storage of the arbor forest in the sample plot were obtained from statistical summary.The biomass per hectare in the Pearl River Delta was 61.52 t/hm²,and the carbon density was 29.95t/hm².In terms of the forest stands,the middle-aged and young-aged forests were dominant,the near-mature and mature forests had higher biomass and carbon density per unit area;The species of Schima superba,Pinus massoniana,Quercus,mixed broadleaf forests and mixed conifer and broadleaf forests had higher biomass and carbon density per unit area,while the Eucalyptus was lower;The spatial distribution pattern of biomass and carbon storage were high in the east and west and low in the south;And the biomass and carbon density per unit area increased with the increase of altitude.The sustainable carbon sink potential of arbor forests can be improved by adjusting the age structure,optimizing the tree species composition,strengthening the tending of young and middle-aged forests,and forest protection,which can provide guidance for the construction and promotion of forest city cluster in Pearl River Delta.

Characteristics of Understory Forest Fuels in Typical Plantations in Northern Guangdong Province

FU Zhigao, WANG Zhilong, XIAO Yihua, XU Han, SHI Xin

2022,(4):  61-71.  doi:10.13466/j.cnki.lyzygl.2022.04.009

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Forest fuels,as the essential material for forest burning,constitute the main body of forest fire behavior.The physicochemical characteristics of forest fuels play an important role in forest fire prevention and fighting.The flammability indexes,including dry-to-fresh quality ratio,equilibrium moisture content,ignition point,calorific value,of shrubs (I),herbs (II),humus (III)and litter IV (d<0.6cm),V (0.6cm≤d<2.5cm)and VI (2.5cm≤d<7.62cm)were determined in five types of plantations (Eucalyptus robusta,Pinus massoniana,Cunninghamia lanceolata,Phyllostachys pubescens,Schima superba)in northern Guangdong Province.The flammability indexes of difference and relationship between different typical forests were analyzed to evaluate the flammability of five types of forest.The results showed that the dry-to-fresh quality ratio of forest fuels were from 41.88% to 85.99%,and the litter V had the highest dry-to-fresh quality ratio among all typical fuels.Moreover,there were significant differences between different typical forest fuels (P<0.01).The content of equilibrium moisture of humus (III)and litter IV,V and VI in five typical forests were 4.77%~5.01%,6.86%~7.27%,8.26%~9.64%,9.94%~10.58%,respectively.The content of equilibrium moisture of litter increased with the increase of diameter,and the content of equilibrium moisture of litter VI was significantly higher than III (P<0.01).The range of ignition points of humus and litter were 264.67~271.00℃ and 248.00~255.17℃,respectively.Moreover,the range of calorific values were 8.47~11.50kJ/g and 16.11~17.92kJ/g,respectively.And the ignition point of humus was significantly higher than litter (P<0.01).Conversely,the calorific value of litter was higher than humus.Person correlation analysis showed that there had a positive commonality between the dry-to-fresh quality ratios of all fuels.Namely,the dry-to-fresh quality ratios were positively correlated between different typical forests.The impact of the equilibrium moisture on the ignition point was greater than dry-to-fresh quality ratio.The fire resistance strength of five plantations was divided into 3 categories,the first group was Schima superba forest with strong fire resistance.The Phyllostachys pubescens forest with medium fire resistance was followed.The third group,including Eucalyptus robusta forest,Pinus massoniana forest and Cunninghamia lanceolate forest,were relatively flammable forests.

Comparative Study on Physical and Chemical Properties and Flame Retardancy of Two Berberis Species

LIU Weiping, JI Wei, ZHANG Jun

2022,(4):  72-79.  doi:10.13466/j.cnki.lyzygl.2022.04.010

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This paper aimed to compare the flame retardant properties of two Berberis species in Gaocheng District of Shijiazhuang City,Hebei Province,and provide theoretical basis for the selection of fire-resistant forest belts of Berberis in garden cities.We examined tree combustibility using big and small branches of new species Berberis thunbergii'Bingchuanhongye' and common garden greening Berberis thunbergii 'Atropurpurea'during fire prevention period (mid-February),used principal component analyses in SPSS 18.0 and Origin 2019 software to analyze the seven physical and chemical properties including moisture content,benzene-alcohol extract content,lignin,polysaccharide,crude ash,ignition point,high and lower caloric values that affected combustibility of trees.Thermogravimetric analysis instruments were used to obtain TG-DTG curve and calculate the pyrolysis kinetics equation to obtain the activation energy (E)and pre-exponential factor (A)in large and small branches among two Berberis species.The pyrolysis characteristics and kinetics parameters were studied,and combustibility of two Berberis species was assessed comprehensively.In general,B.thunbergii'Bingchuanhongye' was more flame retardant than B.thunbergii'Atropurpurea',big branches were more flame retardant than small branches.These results provided an important data for the flame retardancy of two Berberis species.

Effects of Thinning on Ecological Benefits of Cryptomeria fortunei Plantations in High Altitude Area of Western Sichuan

HU Jiayi, WANG Ruihui, LIU Kaili, ZHANG Bin, ZHOU Yuhuai, LI Xuehui, GONG Yingyun

2022,(4):  80-88.  doi:10.13466/j.cnki.lyzygl.2022.04.011

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The thinning experiment was carried out in 9-year-old C.fortunei plantation in high altitude area of Western Sichuan,according to the tree number,four thinning intensities were set up:control group (0%,CK),mild thinning (20%,T1),moderate thinning (35%,T2)and severe thinning (50%,T3),and the differences in stand characteristic factors,soil physicochemical properties,understory species diversity and surface runoff were observed and analyzed among these thinning treatments.On this foundation,analytic hierarchy process and entropy weight method were used to assign weight to get the important value of each index of ecological benefit,and the evaluation score of each index was calculated by combining with the observed data.Ecological benefit evaluation score of each treatment was obtained by comprehensive calculation.The results showed that:from the important value of ecological benefits,the order was stand characteristic factor (0.384 4),soil physicochemical properties (0.254 6),understory vegetation diversity (0.242 8)and surface runoff index (0.118 2).The comprehensive evaluation of ecological benefits found that T3 (71.6)performed the best and then followed by T2 (70.4),T1 (58.9)and CK (28.8).In conclusion,thinning intensities of 50% or 35% could achieve good ecological benefits for 9-year-old C.fortunei plantation,and considering the particularity environment in high altitude areas of western Sichuan,the thinning intensity of 30% was suitable for management of C.fortunea plantations.

Dynamic Change and Influencing Factors of Vegetation Cover over the Past 30 years in the Wutai Mountain Area

REN Tianchen, CHEN Junfeng, LIU Nan

2022,(4):  89-99.  doi:10.13466/j.cnki.lyzygl.2022.04.012

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Based on 25 Landsat remote sensing data sources from 1991 to 2020,the temporal and spatial characteristics of vegetation coverage and its influencing factors in Wutai Mountain were analyzed by binary pixel model,wavelet analysis and partial correlation analysis.The results showed that the FVC values in Wutai Mountain area showed an increasing trend on the whole,in which the mean value of FVC in Wutai County was the highest,and the FVC growth rate in Yuanping City was the highest.There were three main change cycles of 9,12,21 years to control the change of FVC in the whole time domain.The vegetation cover in the study area showed a spatial distribution pattern of "low in the west and high in the east",and the improved area of vegetation cover was much larger than the degraded area.The CV values of Wutai County showed a large negative deviation phenomenon when the altitude was lower than 2 400m,and a large positive deviation phenomenon when the altitude was higher than 2 400m.The FVC values of Fanshi County showed an order as follows:shade slope>sunny slope>half shade slope>half sunny slope;The peak values of FVC in each slope direction of Dai County and Yuanping City appeared in the altitude range of 1 600~2 000m.The negative deviation of CV values in Wutai County,Dai County and Yuanping City increased with the increase of slope.From 1980 to 2015,the mean value of partial correlation coefficient between FVC value and temperature was 0.14,and that between FVC value and precipitation was 0.05.In Wutai Mountain area,the area of forest land and construction land increased,while the area of cultivated land and grassland decreased to varying degrees from 1980 to 2015,and there were vegetation decline problems in human-active areas such as mining areas and scenic spots.

Analysis of Tree Canopy Cover in Built-up Srea of Huize County, Yunnan Province Based on eCognition Image Interpretation

HE Xiaofei, CHEN Xin, WANG Mengyao, MIAO Xue, FAN Changmeng, PENG Jiansong

2022,(4):  100-108.  doi:10.13466/j.cnki.lyzygl.2022.04.013

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Urban ecological construction is an effective way to solve the environmental deterioration caused by the urbanization process,forest canopy coverage is a landmark index to measure urban ecology and reflect the effectiveness of forest city construction,the analysis results of forest canopy coverage can provide reference for the forest city construction of small and medium-sized cities in southwest China.Based on the 0.5m resolution aerial remote sensing images in the built-up area of Huize County from July to August 2019,and the ArcGIS10.4 platform,the canopy coverage and patch distribution of trees in the built-up area of Huize County were calculated and analyzed by using eCognition 9.0 software interpretation and multi-scale segmentation algorithm processing.The results showed that the actual canopy coverage of trees in the built-up area of Huize County was 275.55hm²,which gradually spread from the urban center to the surrounding areas,showing an increasing trend,and the canopy coverage rate of trees was 17.78%.There were 5 270 patches in total,and the overall urban forest was small in area but big in number,with serious fragmentation.The potential forest canopy coverage was 8.98%,with a total of 2 067 patches,and the theoretical value of the maximum forest canopy coverage that could be achieved was only 26.76%.The patch distribution of new and old residential areas was significantly different,and the construction of urban forest played a positive role in promoting the improvement of urban ecology.

Technical Application

A Multi-Temporal and Multi-Feature Larch Plantation Extraction Study Based on GF-1 Images

WANG Xiaoyang, JIANG Youyi, LI Xiao, HU Yaxuan, ZHANG Jiazheng, LIU Bowei

2022,(4):  109-118.  doi:10.13466/j.cnki.lyzygl.2022.04.014

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Larch plantation has become an important tree species in north China,and the afforestation area is increasing year by year.Therefore,the extraction of larch plantation is of great significance for rational utilization of forest resources in China.Based on Mengjiagang Forest Farm within the territory of Huanan County in Heilongjiang Province as the research district,combined with phenological characteristics of larch,the study selected a typical period of GF-1 PMS images as the data source,used forest resources subcompartment data and field survey data as the sample data,extracted image spectral characteristics,texture characteristics,vegetation index and topographic features,and used Random Forest (RF)algorithm to extract the spatial distribution of larch plantation from multi-date and multi-feature angles,so as to obtain the best classification time phase and feature combination of larch plantation.The experimental results showed that the optimal window size was 9×9 by using gray co-occurrence matrix (GLCM)to classify texture features under different windows.The importance of all features was evaluated based on the Gini coefficient,and the highest overall accuracy was selected as the preferred subset.When 84% of all features (spectral,texture,exponential and topographic features were 11,5,9 and 2 respectively)were used for classification,the overall accuracy reached the highest 82.67% (Kappa coefficient was 0.76).The contribution rate of the vegetation index was the highest among all the characteristics.Compared with spectral features,spectral features+ vegetation index,spectral features + texture features and spectral features + terrain factors classification,constructing multi-feature optimization RF classification model can effectively reduce the dimension and improve the classification accuracy of larch plantationforest.

Forest canopy height inversion based on interferometric phase-coherence amplitude method and baseline selection

LUO Hongbin, YUE Cairong, WANG Ning

2022,(4):  119-125.  doi:10.13466/j.cnki.lyzygl.2022.04.015

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Forest canopy height is an important parameter.In this paper,the phase-coherence amplitude method as the forest height inversion model based on airborne multi-baseline PolInSAR data acquired in the Gabonese Republic on the west coast of Central Africa,the RVoG three-stage method is used to calculate the forest canopy height in the phase difference part,and compared the differences of forest canopy height inversion results under four baseline selection methods of PROD,LINE,ECC and VAR.The results show that among the inversion results with four different baseline selections,the best inversion results are obtained using the LINE method for baseline selection with R² of 0.746,RMSE with 7.715m,and BIAS with -3.412m,which are more satisfactory.The inversion accuracy of baseline selection using the PROD and ECC methods is slightly lower than that of the LINE method,and the difference between them is not significant.The R² of the baseline selection inversion results using the ECC method is 0.732,RMSE is 7.918m,and BIAS is 0.139m,and the underestimation and overestimation in the inversion results are more obvious.The inversion results of baseline selection using the PROD method have an R² of 0.720,RMSE of 8.099m,and BIAS of -4.056m,showing a slight overestimation overall.The inversion results of baseline selection by VAR method had the lowest accuracy among all methods,with R² of -0.245,RMSE of 17.079m,and BIAS of 12.945m,and the overall underestimation was more serious,and serious underestimation occurred after the forest canopy height was greater than 10m.The findings suggest that multi-baseline PolInSAR can accurately and efficiently invert forest canopy height,but the baseline selection method has a significant effect on the results.

Application Evaluation of BJ3 Satellite Data in Remote Sensing Monitoring of Pine Wilt Disease

QIN Lin, MENG Xianjin, ZHANG Shuihua, XUE Yadong, LIU Xinke, Xing Peng

2022,(4):  126-133.  doi:10.13466/j.cnki.lyzygl.2022.04.016

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BJ3N is an international leading high-resolution optical remote sensing satellite with independent intellectual property rights of China.The first two satellites were successfully launched in 2021.In order to better understand the application performance of BJ3N,this paper used the relevant image data of BJ3N in Shaoguan City,Guangdong Province to carry out remote sensing monitoring of pine wilt disease,and the application evaluation in image fusion,index calculation,information extraction and other aspects.The results showed that BJ3N data could greatly improve the difference between healthy pines and discolored pines through PANSHARP fusion method and NGRDI index calculation,and effectively enhance the identification effect of discolored pine;the precision rate of intelligently extracting discolored pine through deep learning was 95.8%.,and the recall rate was 88.3%,which met the work needs of remote sensing monitoring of pine wilt disease,and was conducive to the accurate monitoring and prevention of pine wilt disease.

Grassland Vegetation Coverage Retrieval Based on Sentinel-2 Multi-Spectral Remote Sensing Data: A Case Study of Inner Mongolia Autonomous Region

TIAN Haijing, WANG Lin, HAN Liliang, FAN Yunbao, YANG Jilin

2022,(4):  134-140.  doi:10.13466/j.cnki.lyzygl.2022.04.017

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High-precision grassland vegetation coverage remote sensing estimation model is important for quantitative assessment of grassland quality and fine management of grassland.Based on Sentinel-2 multi-spectral remote sensing data and measured sample plots in Inner Mongolia autonomous Region,grassland vegetation coverage was modeled and inverted.The results showed that:1)There was a significant correlation between the 23 vegetation indexes and the measured vegetation coverage (P<0.001),and the highest correlation coefficient was NDVI with a correlation coefficient of 0.834;2)The underestimation of sinusoidal function was more obvious in the high value part (coverage>75%),while the overestimation of linear function was more obvious in the low value part (coverage<25%),by using these two kinds of functions to simulate vegetation coverage,the results were better;3)The grassland types were divided into 6 groups to modeling vegetation coverage respectively.Finally,correlation coefficient between simulated and measured vegetation coverage for the 1 894 sample plots was R²=0.722,P<0.01,RMSE=12%;4)The vegetation coverage of different grassland types in Inner Mongolia from high to low was 78.91% for mountain meadow,73.7% for temperate meadow steppe,53.89% for lowland meadow,52.57% for temperate steppe,32.76% for temperate desert steppe,25.52% for temperate grassland desert and 19.29% for temperate desert.

Estimation of Important Canopy Parameters of Agarwood Based on Hyperspectral Remote Sensing

CHEN Xiaohua, CHEN Zongzhu, LEI Jinrui, WU Tingtian, LI Yuanling

2022,(4):  141-147.  doi:10.13466/j.cnki.lyzygl.2022.04.018

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The use of hyperspectral remote sensing to construct an inversion model of agarwood chlorophyll content and leaf area index is the key to accurate diagnosis of agarwood tree growth and health.Based on the experimental plot of agarwood,the spectral reflectance of the canopy of 6-year-old agarwood and its corresponding chlorophyll content and leaf area index were measured.The result shows:1)There was a certain correlation between the spectral reflectance of agarwood canopy and the chlorophyll content and leaf area index of agarwood leaves,and the correlation varied with different parameters;2)Correlation analysis showed that the chlorophyll content was the most closely related to the spectral reflectance in the infrared bands (760,761,759,765,764 nm),and the leaf area index was closely related to the spectral reflectance in the infrared band (778,777,779,776,782 nm);3)Compared with the fitting effect of vegetation index and characteristic band,it was concluded that the regression model of chlorophyll content and leaf area index based on neural network had the best prediction effect.Therefore,it is believed that hyperspectral technology combined with BP neural network method can monitor the dynamic changes of parameters well,such as chlorophyll content and leaf area index in agarwood.

Research Briefing

Understory Species Diversity and its Relationship with Soil Propertiesof theTypical Public Welfare Forests in Central Yunnan

LI Xiaoying, QIN Wenjing, XU Yanhong, WANG Yuechao, YANG Neng, YANG Ben

2022,(4):  148-156.  doi:10.13466/j.cnki.lyzygl.2022.04.019

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Public welfare forest can play a significant ecological benefit by improving the understory vegetation and soil conditions.However,the composition of understory plants and soil characteristics of the public welfare forests in central Yunnan are not clear.In this study,the species composition and soil physicochemical properties of four typical public welfare forests (Alnus Nepalensi,Pinus Yunnanensis,Castanopsis Orthacantha and Pinus Armandii)in Yuxi were investigated.The species diversity and soil properties of understory shrubs and herbaceous plants were analyzed,and the relationship between species diversity and soil properties was revealed.The results showed that:1)The species composition under Pinus yunnanensis forest was the most abundant (both shrubs and herbs had the highest number of species,both diversity index and richness index were the highest).The lowest species diversity in shrub layer and herb layer were Pinus armandii and Castanopsis orthacantha;2) the soil organic matter of four kinds of public welfare forest were rich,the contents of soil total nutrients (total nitrogen,total phosphorus,total potassium)and available phosphorus in Alnus nepalensis were significantly higher than those in other forests,the soil bulk density,total nitrogen,total potassium and available potassium contents of Castanopsis orthacantha were the lowest;3)Soil available phosphorus,total phosphorus,total potassium and bulk density were the key factors affecting shrub species diversity under public welfare forests,the key factors affecting herbaceous species diversity were soil total phosphorus and pH.Species diversity under public welfare forests in central Yunnan was closely related to soil properties.Attention should be paid to soil acidity-alkalinity,compactness and selective regulation of nitrogen,phosphorus and potassium,so as to improve the structure of understory shrubs and herbaceous plants to achieve the best benefits.

A Provincial-Municipal-County Integrated Forest Carbon Storage Estimating Technology System —Take Guangdong Province as an Example

XUE Chunquan, CHEN Zhenxiong, YANG Jiazhi, ZENG Weisheng, LIN Liping, LIU Ziwei, ZHANG Hongai, SU Zhiyao

2022,(4):  157-163.  doi:10.13466/j.cnki.lyzygl.2022.04.020

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The purpose of this study is to establish the integrated province-city-county forest carbon storage estimation technology system of Guangdong,and provide a method reference for local government to measure forest carbon storage.This study used forest sample plot survey data of the ninth national forest resources continuous inventory of Guangdong Province in 2017,established a simultaneous prediction model with forest volume,biomass and carbon storage as target variables,and stand basal area and stand average height as explanatory variables,each model's determination coefficient R² was above 0.94,MPE average forecast error was less than 3%.The average percentage standard error (MPSE)was less than 15%,and the evaluation indexes showed that the model had high practicability.Based on the sub-class data of 2018 second-class forest resources survey in Guangdong Province,supported by model technology and data coupling technology,the forest reserves of Guangdong Province were translated into forest map patterns in forest resources archive data,and then aggregated into villages,towns,counties,cities and provinces step by step,realizing provincial-city-county integration under the national framework system.The results showed that the system coupling method of carbon storage estimation technology established was scientific and feasible,and the prediction model had high accuracy,which could be popularized and applied in the assessment and evaluation of carbon neutralization goals of provinces,cities and counties.

Study on the Influence of Stand Structure on Stand Growth of Oak Natural Forest in Hunan Province Based on Structural Equation Model

LI Xinjian, YANG Ziduo, HE Haimei, QIU Ziyang, ZHU Guangyu

2022,(4):  164-171.  doi:10.13466/j.cnki.lyzygl.2022.04.021

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Taking Hunan oak natural forest as the research object,this paper adopted 22 stand structure indexes and 3 stand total average growth indexes (average height,basal area and volume),and used Pearson correlation analysis to screen key structural factors.On this basis,a structural equation model was constructed to explore the influence of stand structure on stand growth.The results showed that: 1) stand age had a very significant effect on the three growth indicators (P<0.001);2) Mixing degree and stand density had a significant effect on basal area growth (P<0.001);3) Mixing degree,variation coefficient of diameter at breast height and stand density had a very significant impact on the volume growth (P<0.001),and species composition had a significant impact on it (P<0.01),among them,mixing degree had the greatest impact,and the impact coefficient was as high as 0.515;4) Mixing degree,stand density and species composition indirectly affected the volume growth by directly affecting the basal area growth and the coefficient of variation of DBH size.The research shows that improving the mixing degree of stand species,reasonably controlling the distribution of stand density and tree size,and optimizing the composition of tree species can promote the growth of stand.