Forest and Grassland Resources Research

Current Situation and Outlook of the Construction of Forest and Grassland Fire Prevention Infrastructure under the New Situation

LU Yuan, WANG Guangyu, CHENG Ziyue, YAN Yuqian, ZHANG Heng, WANG Li, YANG Hui, ZOU Quancheng

2023,(6): 1-7. doi:10.13466/j.cnki.lczyyj.2023.06.001

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Forest and grassland fire prevention is a major issue related to safety and development,and a major task for the protection of forest and grass resources.Infrastructure is the hard power of forest and grassland fire prevention work.Strengthening the construction of fire prevention infrastructure and the level of equipment allocation is the fundamental solution to comprehensively improve the comprehensive prevention and control capability of forest and grassland fires in China.This paper put forward the construction idea of how to build forest grassland fire prevention infrastructure under the new situation and made a brief overview of the construction content of related projects,aiming at strengthening the forest grassland fire prevention infrastructure construction.Approaches were provided to for effectively preventing and responding to the threat of forest and grassland fires,especially major fires,as well as for improving the comprehensive prevention and control capacity of forest and grassland fires.

The Value,Existing Problems and Development Suggestions of China's National Park Concession System

WANG Tianwei, LIU Rui

2023,(6): 8-17. doi:10.13466/j.cnki.lczyyj.2023.06.002

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The national park concession system is an innovation of Chinese government concessions in the field of ecological civilization construction,which not only injects funds into the construction of national parks,but also improves the quality of public services through market competition mechanism.It not only implements the basic goal of the public interest of national parks to protect the ecological environment,but also protects the personal interests of indigenous residents.However,in the process of implementation,the national park concession system still faces problems such as the questionable nature of the concession agreement,the defects of the access mechanism and the lack of systematic regulation of the exit mechanism,which hinders the effectiveness of the concession system.On this basis,the franchise agreement should be given the dual nature of both "administrative" and "civil",with an administrative license at the stage of agreement conclusion and a civil contract at the stage of agreement implementation;The franchise access mechanism should be further improved by establishing a franchise management advisory committee,restricting the use of priority renewal rights,and introducing a "negative list" management model.And through the establishment of a temporary takeover system,improve the franchise supervision system and other ways to establish an exit mechanism.

Research on Pathways and Strategies for the Value Realization of Forest,Grassland and Wetland Carbon Sink Products

LI Qing, GOU Lihui, ZHENG Qianhui, YANG Yu, XIA Chaozong

2023,(6): 18-26. doi:10.13466/j.cnki.lczyyj.2023.06.003

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Realizing the value of forest,grassland and wetland carbon sink products is a crucial means of realizing ecological product value.Accelerating the realization of value in these products not only incentivizes market entities to engage in ecological environment protection but also contributes to social welfare by driving employment and income growth.Furthermore,it enhances the carbon sink function of ecosystems,thereby supporting the achievement of "dual carbon" goals.Under the impetus of national policies related to ecological restoration and the realization of ecological product value,the pathways for realizing the value of forest,grassland and wetland carbon sink products have continuously evolved and developed.Throughout the country,various regions have explored and established a series of distinctive and replicable pathways and models for realizing the value of these products.This paper reviews the main pathways for realizing the value of forest grassland and wetland carbon sink products,including ecological compensation,carbon trading,innovative developments in carbon finance,and social capital participation in carbon sequestration and sink enhancement.By incorporating the latest statistical data and typical case studies,the paper objectively reflects China's research progress in promoting the value realization of forest grassland and wetland carbon sink products.It analyzes the challenges faced in realizing the value of these products and proposes strategies and recommendations to facilitate their value realization.

Research and Empirical Analysis of Farmers' Forest Land Transfer Behavior from the Perspective of Social Embeddedness

WANG Wenqi, MEI Yuntian, CHEN Jiayu, ZOU Quancheng, SU Yang

2023,(6): 27-38. doi:10.13466/j.cnki.lczyyj.2023.06.004

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The circulation behavior of farmers' forest land is a decision-making process that integrates economic,cultural,social and other factors,and is an interaction and integration of economic motives and non-economic motives,which is an economic-social behavior.Based on the perspective of social embedding,this paper empirically analyzed the survey data of 1544 sample farmers in 10 provinces,30 counties in China through the multivariate logistic regression model.The resault showed that,circulation behavior of farmers' forest land was not only affected by the independent factors of farmers,but also deeply affected by social cognition,social culture,social network,political system and other social embedded factors,and the circulation behavior of farmers' forest land was a typical social and economic activity.Seven indicators,including forestry management experience,forestry policy cognition,market information cognition,herd imitation behavior,network relationship strength,network relationship communication frequency and government service awareness had significant positive directions for farmers' forest land inflow and outflow behavior,which basically met expectations.The issuance of forestry subsidies had a promoting effect on the inflow of forest land by farmers,the difficulty of applying for forest harvesting indicators had a promoting effect on the outflow behavior of forest land of farmers,and the plot of land love did not passed the significance test,and the significance results of these three indicators exceeded expectations,and to a certain extent,they also reflected the actual difficulties and problems in forestry production and operation.Finally,three policy suggestions were put forward,including regulating the order of forest rights circulation,strengthening forestry subsidy policies,and improving the stability of forestry policies,in order to further promote forest land circulation policies,achieve the optimal allocation of farmers,forest land,technology,capital and other elements,and promote the modernization and development of forestry.

Spatial-Temporal Evolution of Habitat Quality and Its Prediction in Luoxiao Mountain Area in the Past 25 Years

LIU Yan, NIU Xiang, WANG Bing

2023,(6): 39-51. doi:10.13466/j.cnki.lczyyj.2023.06.005

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Analyzing the temporal and spatial variation of habitat quality can provide a basis for ecological protection and restoration in ecologically fragile areas.In this study,the spatio-temporal variation of habitat quality in Luoxiao Mountain from 1995 to 2020 and the variation characteristics of habitat quality in the scenarios of natural development-arable land protection-ecological conservation in 2035 were studied based on land-use type dynamics,InVEST model and patch generation land use simulation (PLUS)model.The results show that 1)Luoxiao Mountain is dominated by forest land,and the proportion of arable land,forest land and grassland area decreased from 1995 to 2020,while the increase of construction land area was as high as 0.69%,and more than 91% was transferred from cultivated land and forest land.2)The overall habitat quality of Luoxiao Mountain is better,and the area of higher and higher habitat quality accounts for 57%;From 1995 to 2020,the habitat quality of Luoxiao Mountain showed a trend of degradation,and the degraded areas were mainly located in Chaling County,Nankang District and Yizhang County.3)Compared with 2020,the proportion of high-grade habitat quality area under the natural development and arable land protection scenarios in 2035 showed a slight decreasing trend,while the proportion of high-grade habitat quality area increased by 7.14% under the ecological protection scenario,so the ecological protection scenario was the best choice for regional sustainable development.It is of great significance to control the transformation of forest land and arable land with higher habitat quality to construction land with lower habitat quality.

Soil Moisture Characteristics and Its Response to Precipitation of Typical Plantation in Mu Us Sandy Land

BAI Xingwen, BU Rigude, HONG Guangyu, LI Wei, SHAO Feizhou, ZHANG Lei

2023,(6): 52-60. doi:10.13466/j.cnki.lczyyj.2023.06.006

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Fluctuations in precipitation patterns affects the ecological stability in arid and semi-arid areas Taking typical Hedysarum laeve plantations,Salix psammophila plantations and moving dunes in Mu Us Sandy land as research objects,through continuous monitoring of precipitation and soil profile water change,the soil moisture change characteristics at 10 cm,30 cm,50 cm,70 cm,90 cm and 110 cm of three kinds of land cover types and their responses to different precipitation magnitude were analyzed.The results showed that:1)The soil moisture content changed from shallow layer to deep layer,the sand dune showed an S-shaped change,the Hedysarum laeve plantation showed a 3-shaped change,and the Salix psammophila plantation showed a continuous increase.2)During the vegetation growing season from May to October,the soil moisture content of the sand dune showed fluctuation,the Hedysarum laeve plantation showed "M" type change,and the Salix psammophila plantation showed "N" type change.3)When precipitation was the same,the response of soil moisture recharge to precipitation was hysteretic,and the initial soil moisture content and precipitation intensity affected the depth of water infiltration.The results of this study provide a theoretical basis for rational utilization and prediction of water resources in the process of ecological construction in arid and semi-arid regions.

Method and Application of Basic Price Evaluation Based on Forest Land Type

LI Chenchen, WU Jianwei, SHI Tian

2023,(6): 61-66. doi:10.13466/j.cnki.lczyyj.2023.06.007

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Evaluating the basic price of forest land,which provides reference prices for forest land circulation,is conducive to regulating the transaction of forest land use rights.Based on the forest land classification data of Wuzhishan City,we take the sample price as the dependent variable and the forest land classification index where the sample point is as the independent variable to establish regression model for different forest land types.Then we get the price of all classification units and the average price of each level is the basic price of forest land.The basic price of forest land in the study area corresponds to its level,showing a decreasing trend from level 1 to level 5.The basic price of arbor economic forest land where mango and lychee grows is the highest,followed by shrub economic forest land where tea grows.Bamboo forest land,short rotation timber forest land,general timber forest land,and general shrub forest land decrease sequentially.The basic price of economic forest land is much higher than timber forest land.The prices of the same type of forest land vary greatly due to different tree species.The basic price reflects the level of different quality forest land,which can provide reference for forest land circulation.The research results are beneficial for revitalizing forestry resources,promoting compensated use of forests,and providing support for protection and rational utilization of natural resource.

Spatial-Temporal Evolution Characteristics and Driving Influence Mechanism of Habitat Quality in Kuye River Basin

YUAN Yuan, SHENG Yan, LIU Linfu, WANG Shuo, LI Juan, AN Li

2023,(6): 67-74. doi:10.13466/j.cnki.lczyyj.2023.06.008

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The Kuye River is located in the ‘ji’ bay in the middle reaches of the Yellow River.It is an important water supply section of the Yellow River.The quality of its habitat is related to the ecological security and people's well-being of the basin.Based on GIS technology,InVEST model and linear regression analysis method were used to reveal the spatial and temporal evolution characteristics of land use and habitat quality in Kuye River Basin from 2000 to 2020.The main driving factors of habitat quality change in Kuye River Basin were further explored.The results showed that :1)In 2020,the grassland area of Kuye River Basin decreased by 6.60 % compared with that in 2000,and the forest land area increased by 35.05 % compared with that in 2000.2)From 2000 to 2020,the Kuye River Basin was dominated by areas of medium and high habitat quality.The overall habitat quality was improved,and the habitat quality was reduced in some areas.3)From 2000 to 2020,the total output value of the secondary industry,the total industrial output value,the total population at the end of the year,the landscape separation index and the habitat quality index showed a significant negative correlation.It can be seen that the industrial development and human activities in the Kuye River Basin have a very significant impact on the decline of habitat quality in the study area.

Effects of Eucalyptus Afforestationon the Soil Organic Carbon Pool on the Hillslope of in the Red Soil Collapsing Erosion Area

LIU Xuejian, ZHANG Zhihua, HAO Beibei, WANG Nan, MA Yu, HE Bin, ZHANG Siyi

2023,(6): 75-81. doi:10.13466/j.cnki.lczyyj.2023.06.009

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Studying the recovery process of soil organic carbon after the Eucalyptus planting provide scientific basis for comprehensive evaluation of soil and water conservation benefit of Eucalyptus afforestation in the red soil collapsing erosion area.Several Eucalyptus afforestation sample plots with similar site conditions but different recovery years,and various slope positions in Wuhua County,Guangdong Province,China were selected as the study area.A comparative analysis was conducted on characteristics of the soil organic carbon pool at different depths with nearby bare land and secondary Pinus massoniana as controls.The soil organic carbon (SOC)of Eucalyptus afforestation was higher than that of bare land at the depths of 0-30 cm,and the lower slope was even high than the natural Pinus massoniana in the collapsing erosion area.This meant that the effects of Eucalyptus afforestation on the recovery of SOC were mainly reflected in the surface soils.In addition,the SOC in the Eucalyptus afforestation ranged from 1.67 kg/m² to 4.65 kg/m²,and the SOC of all slope positions in the light erosion area was higher than that of the bare land (1.91 kg/m²).However,the SOC of the middle slope in the heavy erosion areas and upper slope in the moderate erosion areas were lower than that of the bare land,and the SOC in the lower slope of both areas was close to natural forest.The Eucalyptus afforestation has good recovery effects of soil organic carbon in the light erosion zone or the lower slope,but at the upper or middle slope in moderate and heavy erosion areas,the recovery effects needs to be clarified in longer duration.Therefore,this study highlights that it is necessary to consider the factors of erosion intensity and slope position before selecting the afforestation plants during the process of vegetation restoration in the red soil collapsing erosion area.

Survey and Evaluation of Wildlife Resources in Heilongjiang Huzhong National Nature Reserve

DU Jun, CAO Jiashuo, LI Weidie

2023,(6): 82-90. doi:10.13466/j.cnki.lczyyj.2023.06.010

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Regular survey and continuous monitoring of wildlife resources are important means for biodiversity maintenance,assessment and management.In order to further clarify the basic situation and the changing characteristics of populations of wildlife resources in the Heilongjiang Huzhong National Nature Reserve,a winter survey of veterinary animals and forest-dwelling birds was carried out from November to December in 2022.The footprint chain was adopted as a statistical index for the indirect population survey of animals,and the sample strip method was utilized to estimate the number of populations.The habitat quality was evaluated in terms of habitat fragmentation,conservation status,and development trends.The results showed that 12 species of beasts from 3 orders and 7 families were found in the 56 sample strips,and the populations were quite large in number and distribution,with siberian musk deer (Moschus moschiferus),sable (Martes zibellina),wolverine (Gulo gulo),moose (Alces alces)being the more prominent ones;2 species of forest-dwelling birds from 1 order and 1 family were found,including black-billed capercaillie (Tetrao urogalloides)and hazel grouse (Tetrastes bonasia).The habitat quality of siberian musk deer,wolverin,moose and sable was good,and the habitat quality of mountain hare (Lepus timidus),wapiti (Cervrs canadensis)and black-billed capercaillie was poor.Based on the results of the survey analysis and evaluation,targeted management countermeasures such as the establishment of a sound scientific research and monitoring system and the restoration of wildlife habitat connectivity have been proposed,so as to realize a comprehensive improvement in the level of biodiversity monitoring and protection and management capacity of the nature reserves.

Solution Paths to the Proof Difficulties of Online Illegal Wildlife Trade

CHEN Yong

2023,(6): 91-97. doi:10.13466/j.cnki.lczyyj.2023.06.011

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Illegal wildlife trade of wildlife not only endangers the ecological environment and public health safety,but also breeds a series of crimes such as illegal hunting and transportation,seriously disrupting social order.Due to the low risk and high efficiency of online trade,offline illegal trade is gradually shifting towards online channels,and more and more wild animals are being sold through online channels.Crime is further organized,scaled up,and concealed.Online wildlife trafficking has led to an increasing number of cases,posing a threat to the ecological environment and public health safety.Under the influence of multiple factors,current problems of proving online illegal wildlife trade are characterized by difficulties in evidence collection,investigation,and identification.This may bring a series of negative consequences,such as.Increasing the risk of pathogen transmission and endangering public health safety;Inducing illegal hunting and trade activities,endangering species safety and ecological balance,etc.The way to solve the difficulties of evidence is to use the transportation as a breakthrough point;Strengthening cross regional and multi departmental collaboration;Clarify e-commerce platforms' obligation of assisting in proving;Improving the judicial appraisal mechanism,etc.Implementing these measures helps to accurately combat wildlife crimes and practice the concept of a community of life.

Spatial Distribution of Forest Carbon Storage in the Pearl River Delta Based on Geographically Weighted Regression Model

CAO Cong, GUO Zexin, GUO Yanqing, MO Yanqing, LIU Ping

2023,(6): 98-104. doi:10.13466/j.cnki.lczyyj.2023.06.012

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Based on the data of 419 consecutive forest resource inventory plots in the Pearl River Delta region in 2017,the spatial distribution of forest carbon storage in the Pearl River Delta region was predicted using the Ordinary Least Squares (OLS)model and four Geographically Weighted Regression (GWR)models.The results showed that all four GWR models had better model fitting performance and independent sample test results than OLS models,with MGWR (Gaussian)model having the best fitting performance and GWR (Gaussian)model having the best independent sample test results;Using the GWR (Gaussian)model to draw a spatial distribution map of forest carbon storage,the estimated carbon storage per unit area of the Pearl River Delta forest is 6.15-81.52 t/hm²,with an average value of 33.46 t/hm².The estimation error is better than the OLS model,and the overall spatial distribution pattern shows a high center and low edge.It also provides a new method and idea for the estimation of forest carbon stocks in the Pearl River Delta.

Single-TreeVolume Estimation of Pinus massoniana based on Airborne LiDAR Point Cloud

TANG Jiajun, WANG Gang, CHAI Zongzheng

2023,(6): 105-112. doi:10.13466/j.cnki.lczyyj.2023.06.013

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In order to improve the accuracy and efficiency of forest single-tree volume estimation,the typical Pinus massoniana forest in the suburban area of Zhijin County,Guizhou Province was selected as the research object.Based on airborne LiDAR point cloud and sample survey data,a single-tree structure parameter estimation model for P.massoniana based on airborne LiDAR point cloud data was constructed using extracted tree height,crown width,crown projection area,and crown volume as variables.The research results indicate that:1)There was a good correlation between the height and crown width factors of P.massoniana single-tree extracted from point cloud data and actual survey data,with a determination coefficient of R² above 0.7 and relatively high accuracy,which could be used to construct a single-tree volume model of P.massoniana.2)On the basis of the classic nonlinear CAR model,an enumeration method was used to construct 11 models that combined four variables:tree height,crown width,crown projected area,and crown volume.Among them,the model containing three stand factors,tree height,crown width,and crown volume,performed the best,with an R² of 0.774 1.3)Tree height,crown width and crown volume were identified as key factors in estimating the individual volume of P.massoniana,with tree height contributing the most and showing a highly significant positive correlation with individual volume (P<0.001).It is feasible to extract single tree structural parameters using airborne LiDAR point cloud data and construct a single tree volume model based on nonlinear CAR model to estimate the single tree volume of P.massoniana.This method not only meets the accuracy requirements of forest resource surveys but also effectively improves survey efficiency.

Characterization of Soil Ecological Stoichiometry in Plantation Forests of Different Stand Ages of Sonneratia apetala

LI Li, WU Yuehong, XIAO Zexin, JI Yanling, LIN Wenhuan, ZHU Xiaowu, FAN Zhenzhen

2023,(6): 113-119. doi:10.13466/j.cnki.lczyyj.2023.06.014

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To investigate the changes in soil physicochemical properties and its ecological stoichiometric characteristics in different stand ages,the contents of pH,total dissolved salt (TDS),organic carbon (SOC),total nitrogen (TN),available nitrogen (AN),total phosphorus (TP),available phosphorus (AP),total potassium (TK),and available potassium (AK)of the 0~30 cm soil layer of three stand ages of 10,15,and 22 a were measured,the stoichiometric ratios were calculated,and the correlation between each index was analyzed.The results showed that:1)After afforestation,soil pH showed a decrease followed by an increase and then a decrease,soil nutrients increased significantly,SOC and TN were higher than the national soil average,and TP was slightly lower than the national soil average,indicating that the soil C and N content in the study area was relatively high;2)there were significant differences in soil physicochemical properties and ecological stoichiometric ratios among different stand ages;with the increase of stand age,soil pH increased and then decreased,SOC,TN,AN,TP and AK contents decreased and then increased,and the changes of TK and AP were not obvious;3)The growth and development of Sonneratia apetala forest may be limited by N,especially in the period of young and middle stand age.The plantation of Sonneratia apetala forest had a significant regulatory effect on the restoration of soil nutrients in mangrove wetlands.

Spatio-Temporal Pattern Analysis of Vegetation NPP in Yunnan Province Based on Improved CASA Model

QIAN Hui, ZHANG Chao, FAN Jinming, DENG Zaichun, ZHU Xiali, LI Chengrong

2023,(6): 120-128. doi:10.13466/j.cnki.lczyyj.2023.06.015

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Vegetation net primary productivity (NPP)is one of the indicators to measure the level of ecosystem productivity,it is of great significance to estimate it by using the combination of ecology and remote sensing.In this study,we applied the improved CASA model;based on the MODIS vegetation index product,meteorological data,and land cover data;estimated the vegetation NPP in Yunnan Province in 2000,2005,2010,2015,and 2020,and explored its spatial distribution characteristics using the Moran's I index,Getis-Ord Gi^* hotspot analysis,and overlaying analysis with China's ecologically Functional Protected Areas in China were superimposed and analyzed.The results showed that:1)the vegetation NPP in Yunnan Province in the past 20 years showed a trend of decreasing and then increasing trend,with an average value of 822.98 gc/(m² a);the monthly vegetation NPP reached the highest in summer and the lowest in winter;and among the different vegetation types,the evergreen broadleaf forests had the highest NPP values.2)The spatial distribution of vegetation NPP decreased from south to north in each year,and the global spatial autocorrelation Moran 's I index was greater than 0.7.The NPP hot spots were mainly located in the southwestern border of Yunnan,and the cold spots were located in the northwestern and central urbanization areas of Yunnan.3)NPP hotspot areas superimposed with ecological function reserve intersected in Xishuangbanna Ecological Function Reserve and Southwest Karst Ecological Function Reserve,and the superimposed area accounted for 23%~26% of the total area of hotspot areas in each year.The study shows that NPP in Yunnan Province has shown a fluctuating upward trend in the past 20 years,and the results can provide scientific references for vegetation monitoring and ecological environmental protection in Yunnan Province.

Study on Species Composition and Competition Relationship of Camellia sinensis var.assamica Community in Yinggeling

ZHU Zicheng, QI Chunlin, YANG Xiaobo, LI Donghai, SU Fan

2023,(6): 129-136. doi:10.13466/j.cnki.lczyyj.2023.06.016

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In order to explore the ecological status and interspecific relationship of Camellia sinensis var.assamica,and to provide reference for the subsequent conservation and utilization of Camellia sinensis var.assamica populations,species composition and competition relationship in the Camellia sinensis var.assamica community were studied by sample method and circle method.The results were:1)A total of 395 plant species (including 5 varieties and 1 variant)were recorded in the study,belonging to 217 genera in 102 families.Among them,Rubiaceae,Lauraceae,Fagaceae,etc.are the dominant families,Ficus,Lasianthus,Syzygium,etc.are the dominant genus,and Camellia sinensis var.assamica,Heptapleurum heptaphyllum,Psychotria asiatica,Engelhardia roxburghiana,and Lithocarpus caudatilimbus are the dominant species in the community.2)The competition of Camellia sinensis var.assamica in the community mainly came from interspecies,accounting for 90.02%,and the competition intensity of each species for Camellia sinensis var.assamica was ranked as follows:Camellia sinensis var.assamica>Engelhardia roxburghiana>Heptapleurum heptaphyllum>Lithocarpus caudatilimbus>Wendlandia uvariifolia>Cratoxylum cochinchinense.3)The competition intensity gradually decreased with the increase of the diameter at breast height of Camellia sinensis var.assamica,and there were significant differences between the small tree and the middle tree stage,but there was no significant difference after the large tree stage.The competition intensity of the I,II and III stages accounted for 96.10% of the total competition intensity,indicating that Camellia sinensis var.assamica was under greater competitive pressure at small diameter at breast height and less competition at old tree stage.4)There was a significant negative correlation between the diameter at breast height of Camellia sinensis var.assamica and the competitive intensity.So,in the protection of Camellia sinensis var.assamica,the protection of individuals with small diameter at breast height should be strengthened,so that the transition to large diameter at breast height can be smoothly made,and the cultivation of small tea seedlings and the control of tea fruits should be strengthened to promote their population renewal.

Effect of Throughfall Reduction on Sap Flow of Pinus sylvestris var.mongolica in Sandy Land of Northwest Liaoning

SHI Zheyu, LI Zihao

2023,(6): 137-145. doi:10.13466/j.cnki.lczyyj.2023.06.017

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In order to investigate the effect of reduced throughfall on the stem sap flow rate of Pinus sylvestris var.mongolica and its relationship with environmental factors,we uesed the thermal diffusion sap flow probe (TDP)to continuously monitor the stem sap flow rate of Pinus sylvestris var.mongolica plantation in northwest Liaoning,along with various environmental factors.The study site was divided into plots with reduced throughfall (30% artificial interception)and plots with normal rainfall.This paper analyzes and discusses the daily,nightly,and monthly variations in stem sap flow rate of Pinus sylvestris var.mongolica under different weather conditions,utilizing the data of stem sap flow from April to October (growing season)of 2018.The findings of this study are as follows:1)The sap flow rate of Pinus sylvestris var.mongolica was significantly higher in the throughfall reduction plots compared to the control group.The difference in sap flow rate between daytime and nighttime varied with different weather conditions,with the highest difference observed under sunny conditions,followed by rainy and cloudy conditions.2)Following rainfall,the onset of stem sap flow in the throughfall reduction plots was earlier than in the control group,however,the average daily growth rate of stem sap flow in the control group was higher than in the throughfall reduction group.3)The sap flow rate of Pinus sylvestris var.mongolica increased first and then decreased during the growing season,and it was higher in summer than in spring and autumn.4)The sap flow rate of Pinus sylvestris var.mongolica was positively correlated with photosynthetically active radiation and air temperature,but negatively correlated with air relative humidity.Hence,the sap flow rate of Pinus sylvestris var.mongolica increased under the scenario of throughfall reduction,and it provides a scientific reference for the plantation management in the future.

Advances in Remote Sensing Retrieval of Forest Aboveground Biomass

REN Xiaoqi, HOU Peng, CHEN Yan

2023,(6): 146-158. doi:10.13466/j.cnki.lczyyj.2023.06.018

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Forest aboveground biomass is one of the key indicators to reflect the status of forest ecosystem,which is of great significance to global climate change and China's carbon peak and carbon neutrality.With the rapid development and increasing maturity of remote sensing technology,it has become the main technical means for retrieving above-ground forest biomass in large areas.In this paper,the research progress of remote sensing inversion of forest aboveground biomass was discussed from two aspects through systematic review of relevant literatures at home and abroad.From the perspective of data source,it can be summarized as inversion methods of optical remote sensing data,synthetic aperture radar data and LiDARdata,and the effective information,advantages and limitations provided by each data source are expounded and analyzed.From the perspective of inversion model,it can be summarized as multiple regression model,machine learning algorithm and mechanism model,and the characteristics of different models are discussed and analyzed combined with practical application cases.Finally,this paper summarized the existing problems in the inversion of forest above-ground biomass by remote sensing,and prospected the direction and hotspots of forest above-ground biomass inversion by remote sensing in the future.

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