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Understory seedlings of Quercus mongolica survive by phenological escape

Forest Ecosystems 2024年第2期11卷 236-246页

作者： Shixiong Wu Ying Liu Lulu He Wei Zeng Qijing Liu College of forestry Beijing Forestry UniversityBeijing100083China

Understanding understory seedling regeneration mechanisms is important for the sustainable development of temperate primary forests in the context of increasingly intense climate warming *** poor regeneration of dominant tree species,however,is one of the biggest challenges it faces at the ***,the regeneration of the shade-intolerant Quercus mongolica seedling is difficult in primary forests,which contrasts with the extreme abundance of understory seedlings in secondary *** mechanism behind the interesting phenomenon is still *** study used in-situ monitoring and nursery-controlled experiment to investigate the survival rate,growth performance,as well as nonstructural carbohydrate (NSC) concentrations and pools of various organ tissues of seedlings for two consecutive years,further analyze the understory light availability and simulate the foliage carbon (C) gain in the secondary and primary *** suggested that seedlings in the secondary forest had greater biomass allocation aboveground,height and specific leaf area (SLA) in summer,which allowed the seedling to survive longer in the canopy closure *** light availability and positive C gain in early spring and late autumn are key factors affecting the growth and survival of understory seedlings in the secondary forest,whereas seedlings in the primary forest had annual negative carbon *** the growing season,the total NSC concentrations of seedlings gradually decreased,whereas those of seedlings in the secondary forest increased significantly in autumn,and were mainly stored in roots for winter consumption and the following year's summer shade period,which was verified by the nursery-controlled experiment that simulated autumn enhanced light availability improved seedling survival rate and NSC *** conclusion,our results revealed the survival trade-off strategies of Quercus mongolica seedlings and highlighted the necessity of high light availability d

关键词： Carbon gain Nonstructural carbohydrate Recruitment Trade-off Biomass allocation

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Three-dimensional(3.)parametric measurements of individual gravels in the Gobi region using point cloud technique

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Journal of Arid Land 2024年第4期16卷 500-517页

作者： JING Xiangyu HUANG Weiyi KAN Jiangming College of Engineering Beijing Forestry UniversityBeijing 100083China Key Laboratory of State forestry Administration on forestry Equipment and Automation Beijing 100083China

Gobi spans a large area of China,surpassing the combined expanse of mobile dunes and semi-fixed *** presence significantly influences the movement of sand and ***,the complex origins and diverse materials constituting the Gobi result in notable differences in saltation processes across various Gobi *** is challenging to describe these processes according to a uniform ***,it becomes imperative to articulate surface characteristics through parameters such as the three-dimensional(3.)size and shape of *** morphology information for Gobi gravels is essential for studying its genesis and sand *** enhance the efficiency and information yield of gravel parameter measurements,this study conducted field experiments in the Gobi region across Dunhuang City,Guazhou County,and Yumen City(administrated by Jiuquan City),Gansu Province,China in March 2023.A research framework and methodology for measuring 3. parameters of gravel using point cloud were developed,alongside improved calculation formulas for 3. parameters including gravel grain size,volume,flatness,roundness,sphericity,and equivalent grain *** multi-view geometry technology for 3. reconstruction allowed for establishing an optimal data acquisition scheme characterized by high point cloud reconstruction efficiency and clear ***,the proposed methodology incorporated point cloud clustering,segmentation,and filtering techniques to isolate individual gravel point *** point cloud algorithms,including the Oriented Bounding Box(OBB),point cloud slicing method,and point cloud triangulation,were then deployed to calculate the 3. parameters of individual *** systematic processes allow precise and detailed characterization of individual *** gravel grain size and volume,the correlation coefficients between point cloud and manual measurements all exceeded 0.9000,confirming the feasibility of the proposed methodol

关键词： Gobi gravels three-dimensional(3.)parameters point cloud 3. reconstruction Random Sample Consensus(RANSAC)algorithm Density-Based Spatial Clustering of Applications with Noise(DBSCAN)

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Object use in insects

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Insect Science 2024年第4期31卷 1001-1014页

作者： Chao Wen Cai Wang Xiaoli Guo Hongyu Li Haijun Xiao Junbao Wen Shikui Dong School of Grassland Science Beijing Forestry UniversityBeijingChina College of forestry and Landscape Architecture South China Agricultural UniversityGuangzhouChina beijing Key Laboratory for Forest Pest Control Beijing Forestry UniversityBeijingChina

Insects are the most diverse group of organisms in the animal kingdom,and some species exhibit complex social *** research on insect object use is still in its early stages,insects have already been shown to display rich object-use *** review focuses on patterns and behavioral flexibility in insect object-use behavior,and the role of cultural evolution in the development of object-use *** use in insects is not widespread but has been documented in a diverse set of *** insects can use objects flexibly and display various object-use *** mammals and birds,insects use objects in diverse activities,including foraging,predator defense,courtship,and ***,pre-existing manipulative behaviors,and anatomical structure affect innovations in object *** addition,learning and imitation are the main mechanisms underlying the spread of object-use behaviors within *** that insects are one of the major animal groups engaging in object use,studies of insect object use could provide general insights into object use in the animal kingdom.

关键词： cognition evolution insects learning object use

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Nitrogen addition increased resistance of resident plant community to Solidago canadensis invasion by altering allelopathic effect

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Journal of Plant Ecology 2024年第2期17卷 110-121页

作者： Jing-Fang Cai Kai Sun Lin Li Si-Ha A Yi-Luan Shen Hong-Li Li School of Ecology and Nature Conservation Beijing Forestry UniversityBeijing 100083China The Key Laboratory of EcologicalProtection in the Yellow River Basin of National forestry and Grassland Administration Beijing Forestry UniversityBeijing 100083China

Allelopathy plays an important role in the interaction between invasive and resident *** nitrogen(N)deposition has become a global problem,but it is unclear whether N enrichment affects the interaction between invasive and resident plants by affecting their ***,we performed a greenhouse experiment in which the resident plant community was grown under two levels of invasion by ***(invasion *** invasion)and fully crossed with two levels of allelopathy(with or without adding activated carbon)and two levels of N addition(with or without).The resident plant communities were constructed with eight herbaceous species that often co-occur with *** results showed that both allelopathy of *** and the resident plants had obvious positive effects on their own *** addition had more obvious positive effects on the resident plants under invasion than those that were not ***,N addition also altered the allelopathy of resident ***,N addition improved the allelopathy of resident plants when they were invaded but decreased the allelopathy of resident plants when they grew *** nitrogen addition had no obvious effect on ***,it reduced the allelopathy of *** results suggest that N addition could improve the resistance of resident plants to invasion by improving the allelopathy of resident plants and reducing the allelopathy of *** fndings provide a scientifc basis to manage and control the *** invasion.

关键词： allelochemicals biological invasion nutrient input nitrogen addition resident plants Solidago canadensis

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Variability of urban fractional vegetation cover and its driving factors in 3.8 cities in China

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Science China Earth Sciences 2024年第2期67卷 466-482页

作者： Fei FENG Xin YANG Baoquan JIA Xiaoting LI Xianwen LI Chengyang XU Kaicun WANG Research Centre of Urban forestry Key Laboratory for Silviculture and Forest Ecosystem of State Forestry and Grassland AdministrationBeijing Forestry UniversityBeijing100083China State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal UniversityBeijing100875China Research Institute of forestry Chinese Academy of ForestryBeijing100091China School of Architecture Tsinghua UniversityBeijing100084China College of Urban and Environmental Sciences Sino-French Institute for Earth System ScienceInstitute of Carbon NeutralityPeking UniversityBeijing100871China

Urban green space promotes the health of urban residents,enhances urban ecosystem biodiversity,mitigates environmental pollution,and attenuates urban heat island ***,urban vegetation cover is highly heterogeneous and difficult to *** this study,the variation of urban fractional vegetation cover(FVC)in 3.8 cities in China from 1990 to2022 was quantified based on Landsat satellite data at a 3.-m *** was found that from 1990 to 2005,due to increases in building density and impervious surfaces in cities,the national mean urban vegetation cover decreased from 0.3. to ***2005,urban vegetation cover began to reverse,reaching 0.45 in *** increasing trend was most pronounced in newly built urban *** decrease in average urban vegetation cover before 2005 was mainly due to the expansion of low vegetation cover areas,while the increase in urban vegetation cover after 2005 manifested as the expansion of high vegetation cover *** reversal in the trend of urban vegetation cover change after 2004 is related to the gradual implementation of national policies requiring increased urban green space *** urban gross domestic product(GDP)showed the highest correlation with changes in urban vegetation *** large and medium-sized cities,the top three factors influencing vegetation cover were GDP,urban population,and ***,for cities in arid/semi-arid regions,changes in vegetation cover were more sensitive to climatic factors(such as precipitation).Although the urban vegetation cover in China has substantially increased in recent years,the urban green space in small-sized cities and in the old urban districts of large-sized cities still have room to improve.

关键词： Urban vegetation Urban vegetation cover Urbanization Remote sensing

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High leaf area index expands the contrasting effect of climate warming on Western Siberia taiga forests activity before and after 2000

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Journal of Geographical Sciences 2024年第1期34卷 131-145页

作者： SUN Han WANG Xiangping State Key Laboratory of Efficient Production of Forest Resources Beijing Forestry UniversityBeijing 100083China School of Ecology and Nature Conservation Beijing Forestry UniversityBeijing 100083China

The taiga vegetation in Western Siberia has been seriously threatened by climate warming in recent ***,how vegetation in different growing states and climate conditions responds to climate changes differently is still *** we explore the vegetation activity trends in Western Siberia taiga forests using the annual rate of change in leaf area index(LAI)during 1982–2018 so as to answer two questions:(1)how did climate warming affect taiga vegetation activity in the recent last decades?(2)Did the growing state of taiga forest affect its response to climate warming?Our results revealed that climate warming promoted taiga vegetation activity in Western Siberia before ***,continuous warming caused excessive evapotranspiration and led to decreased vegetation activity after ***,the intensity of vegetation growth response to warming was positively related to canopy height and LAI,indicating that both the positive and negative effects of warming were more significant in taiga forests in better growing *** these forests generally have higher productivity and play more important roles in ecosystem functioning(e.g.,carbon sink and biodiversity conservation),our results highlight their vulnerability to future climate change that need more research attention.

关键词： climate warming taiga forest leaf area index(LAI) vegetation activity Western Siberia

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The clutch size,incubation behavior of Reeves’s Pheasant(Syrmaticus reevesii) and their responses to ambient temperature and precipitation

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Avian Research 2024年第1期15卷 72-80页

作者： Ting Jin Shuai Lu Yunqi Wang Junqin Hua Zhengxiao Liu Qian Hu Yating Liu Yuze Zhao Jianqiang Li Jiliang Xu School of Ecology and Nature Conservation Beijing Forestry UniversityBeijing100083China State Key Laboratory of Efficient Production of Forest Resources Beijing Forestry UniversityBeijing100083China

Weather conditions play a pivotal role in embryo development and parental incubation costs,potentially impacting the clutch size and incubation behavior of *** these effects is crucial for bird ***’ s Pheasant(Syrmaticus reevesii) is a threatened species endemic to China,which is characterized by female-only ***,there is a lack of information regarding the impact of weather conditions on clutch size and incubation behavior in this *** satellite tracking,we tracked 27 wild female Reeves’ s Pheasants from 2020 to 2023.in Hubei Province,*** explored their clutch size and incubation behavior,as well as their responses to ambient temperature and *** size averaged 7.75 ±1.3.,had an association with average ambient temperature and average daily precipitation during the egglaying period,and was potentially linked to female breeding *** the incubation period,females took an average of 0.73.±0.46 recesses every 24 h,with an average recess duration of 100.80 ±73.3. min and an average nest attendance of 92.98 ±5.27%.They showed a unimodal recess pattern in which nest departures peaked primarily between 13.00 and 16:***,females rarely left nests when daily precipitation was *** duration and nest attendance were influenced by the interaction between daily mean ambient temperature and daily precipitation,as well as day of ***,there was a positive correlation between clutch size and recess *** results contribute valuable insights into the lifehistory features of this endangered species.

关键词： Ambient temperature Clutch size Incubation behavior Precipitation Reeves’s Pheasant

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Adaptive active inceptor design under shared control architecture for nonlinear pilot-induced oscillations

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Chinese Journal of Aeronautics 2024年第6期37卷 276-292页

作者： Xiaoyu LIU Liguo SUN Wenqian TAN Shuting XU Junkai JIAO School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China College of Engineering Beijing Forestry UniversityBeijing 100083China

This paper presents a Shared Control Architecture(SCA)between a human pilot and a smart inceptor for nonlinear Pilot Induced Oscillations(PIOs),e.g.,category II or III *** innovation of this paper is that an intelligent shared control architecture is developed based on the intelligent active inceptor technique,i.e.,Smart Adaptive Flight Effective Cue(SAFE-Cue).A deep reinforcement learning approach namely Deep Deterministic Policy Gradient(DDPG)method is chosen to design a gain adaptation mechanism for the SAFE-Cue *** doing this,the gains of the SAFE-Cue will be intelligently tuned once nonlinear PIOs triggered;meanwhile,the human pilot will receive a force cue from the SAFE-Cue,and will consequently adapting his/her control *** second innovation of this paper is that the reward function of the DDPG based gain adaptation approach is constructed according to flying *** the premise of considering failure situation,task completion qualities and pilot workload are also taken into ***,the proposed approach is validated using numerical simulation experiments with two types of scenarios:lower actuator rate limits and airframe *** Inceptor Peak Power-Phase(IPPP)metric is adopted to analyze the human-vehicle system simulation *** and analysis show that the DDPG based sharing control approach can well address nonlinear PIO problems consisting of Categories Ⅱ and Ⅲ PIO events.

关键词： Shared control architecture Activeinceptor Deep reinforcement learning Nonlinear pilot-induced oscillations Human-vehicle system

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Use of evergreen and deciduous plants by nocturnal-roosting birds:A case study in beijing

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Avian Research 2024年第2期15卷 211-218页

作者： Yexi Zhao Jiayu Zhang Zihan Li Qinmijia Xie Xin Deng Chenxi Zhang Nan Wang School of Ecology and Nature Conservation Beijing Forestry UniversityBeijing 100083China

With continually increasing urbanization,the land cover in urban areas continues to change,resulting in the loss of *** are highly sensitive to changes in *** forest birds perch on plants that provide increased safety to reduce the risk of predation,and small birds may also consider insulation when using roosting plants in winter because of cold *** plants thus shape the nocturnal roosting environment of urban birds,and proper planting is essential for the survival of birds at *** use of roosting plants by urban birds should therefore be studied to provide a reference for *** the current study,we observed 1865 nocturnal roosting birds in beijing from 2021 to 2022,with 23.species of birds from 12 families and 45 species of plants from 22 families *** chinensis exhibited the highest bird rarity-weighted richness,followed by Fraxinus pennsylvanica,Phyllostachys propinqua,Pinus tabuliformis,and Ulmus *** diameter at breast height,tree height,and crown width of plants used by birds was largest in summer and smallest in winter,and the perch height of birds was the highest in spring and summer and the lowest in *** used the highest proportion of deciduous plants in summer and the highest proportion of evergreen plants in winter.A significant seasonal difference in the use of evergreen and deciduous plants by small birds was noted,with a preference for deciduous plants in summer and evergreen plants in winter,while this preference was not found in large *** findings indicate that evergreen plants provide a vital nocturnal roosting environment for small birds in *** provide a better nocturnal roosting habitat for urban birds,we recommend paying attention to the combination of evergreen and deciduous plants when carrying out landscape construction.

关键词： Nocturnal roosting Roosting plant Seasonal variation Urban bird

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Design of multi-section luffing apple pruning equipment and cutting test of the key components

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International Journal of Agricultural and Biological Engineering 2024年第1期17卷 109-117页

作者： Siyuan Tong Wenbin Li Yaxiong Wang Lei Zhang Feng Kang School of Technology Beijing Forestry UniversityKey Lab of State Forestry and Grassland Administration for Forestry Equipment and AutomationBeijing 100083China

In order to reduce the labor intensity and improve the efficiency of pruning,this study designed a multi-section luffing apple pruning equipment suitable for apple orchards in hilly and mountainous areas of *** the essay,the structure and working principle of the equipment are expounded,the cutter was analyzed,and the parameters were *** the self-made test bench to simulate the field experiment,this study selected the ratio of cutting speed to feeding speed and feeding speed as the influencing factors and took the cut-off rate,cutting efficiency and cutting power as the objectives to carry out single factor experiment and quadratic regression orthogonal *** test results show that the cutting power increases with the increase of ratio of cutting speed to feeding speed,and the cut-off rate and cutting efficiency first increase and then *** the feeding speed increases,the cutting efficiency and power increase,and the cut-off rate *** the cutoff rate was greater than 80%,the optimal combination of operating parameters was the feeding speed of 0.55 m/s and ratio of cutting speed to feeding speed of *** this combination,the cut-off rate was 84.9%,the cutting efficiency was 13.1,and the cutting power was 175.7 *** error between the predicted target value of the model and the average measured target value was less than 7%,so the test results are *** to the obtained optimal operating parameters,the actual cutting experiment of the pruning equipment in the field was carried out,and the cutting rate was 96.3.,which meet the design *** study can also meet the needs of mechanized pruning of fruit trees with different crown shapes,improve the applicability of pruning equipment,and provide support for the development of mechanized pruning equipment in China.

关键词： apple pruning equipment cutting test optimal parameters regression analysis

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