This paper proposes a distributed event-triggered control(ETC)framework to address cooperative target fencing challenges in UAV swarm.The proposed architecture eliminates the reliance on preset formation parameters wh...This paper proposes a distributed event-triggered control(ETC)framework to address cooperative target fencing challenges in UAV swarm.The proposed architecture eliminates the reliance on preset formation parameters while achieving multi-objective cooperative control for target fencing,network connectivity preservation,collision avoidance,and communication efficiency optimization.Firstly,a differential state observer is constructed to obtain the target's unmeasurable states.Secondly,leveraging swarm selforganization principles,a geometric-constraint-free distributed fencing controller is designed by integrating potential field methods with consensus theory.The controller dynamically adjusts inter-UAV distances via single potential function,enabling coordinated optimization of persistent network connectivity and collision-free motion during target fencing.Thirdly,a dual-threshold ETC mechanism based on velocity consensus deviation and fencing error is proposed,which can be triggered based on task features to dynamically adjust the communication frequency,significantly reduce the communication burden and exclude Zeno behavior.Theoretical analysis demonstrates the stability of closed-loop systems.Multi-scenario simulations show that the proposed method can achieve robust fencing under target maneuverability,partial UAV failures,and communication disturbances.展开更多
In order to restore a degraded alkaline grassland, the local government implemented a large restoration project using fences in Changling county, Jilin province, China, in 2000. Grazing was excluded from the protected...In order to restore a degraded alkaline grassland, the local government implemented a large restoration project using fences in Changling county, Jilin province, China, in 2000. Grazing was excluded from the protected area, whereas the grazed area was continuously grazed at 8.5 dry sheep equivalent（DSE）/hm2. In the current research, soil and plant samples were taken from grazed and fenced areas to examine changes in vegetation and soil properties in 2005, 2006 and 2008. Results showed that vegetation characteristics and soil properties improved significantly in the fenced area compared with the grazed area. In the protected area the vegetation cover, height and above- and belowground biomass increased significantly. Soil pH, electrical conductivity and bulk density decreased significantly, but soil organic carbon and total nitrogen concentration increased greatly in the protected area. By comparing the vegetation and soil characteristics with pre-degraded grassland, we found that vegetation can recover 6 years after fencing, and soil pH can be restored 8 years after fencing. However, the restoration of soil organic carbon, total nitrogen and total phosphorus concentrations needed 16, 30 and 19 years, respectively. It is recommended that the stocking rate should be reduced to 1/3 of the current carrying capacity, or that a grazing regime of 1-year of grazing followed by a 2-year rest is adopted to sustain the current status of vegetation and soil resources. However, if N fertilizer is applied, the rest period could be shortened, depending on the rate of application.展开更多
Fencing is the most common land-management practice to protect grassland degradation from livestock overgrazing on the Tibetan Plateau.However,it is unclear whether fencing reduces CO_(2),CH_4,and N_2O emission.Here,w...Fencing is the most common land-management practice to protect grassland degradation from livestock overgrazing on the Tibetan Plateau.However,it is unclear whether fencing reduces CO_(2),CH_4,and N_2O emission.Here,we selected four vegetation types of alpine meadow(graminoid,shrub,forb,and sparse vegetation)to determine fencing effects on ecosystem respiration(Re),CH_4,and N_2O fluxes during the growing season.Despite increased average monthly ecosystem respiration(Re)for fenced graminoid vegetation at the end of the growing season,there was no significant difference between grazing and fencing across all vegetation types.Fencing significantly reduced average CH_4 uptake by about 50%in 2008 only for forb vegetation and increased average N_2O release for graminoid vegetation by 38%and 48%in 2008 and 2009,respectively.Temperature,moisture,total organic carbon,C/N,nitrate,ammonia,and/or bulk density of soil,as well as above-and belowground biomass,explained 19%~71%and 6%~33%of variation in daily and average Re and CH_4 fluxes across all vegetation types,while soil-bulk density explained 27%of variation in average N_2O fluxes.Stepwise regression showed that soil temperature and soil moisture controlled average Re,while soil moisture and bulk density controlled average CH_4 fluxes.These results indicate that abiotic factors control Re,CH_4,and N_2O fluxes;and grazing exclusion has little effect on reducing their emission—implying that climatic change rather than grazing may have a more important influence on the budgets of Re and CH_4 for the Tibetan alpine meadow during the growing season.展开更多
To avoid wildlife-human conflict several solutions are used, like electrical fences, the most expensive solution. Nowadays, technology enables alternative and cheaper approaches for conservation projects. A technologi...To avoid wildlife-human conflict several solutions are used, like electrical fences, the most expensive solution. Nowadays, technology enables alternative and cheaper approaches for conservation projects. A technological device was developed to detect elephants, moving on their habitat, and predict and react by avoiding confrontation with man. The devices were tested in field experiments, and proved to be efficient in capturing floor vibration, and air-sound signals. Collected data also enabled the estimation of the vibration-source by calculus (using triangulation), revealing the importance of the methodology for real-time location and tracking of high mass animals (e.g. elephants). Building up a mesh of devices, separated 25 m from each other, is estimated as possible to monitor and identify different animals (by discriminating patterns) in an area, like a virtual fencing system. Though the devices may be effective for animal behaviour research, or even animal communication analysis, or other Biology field, other applications outside Biology are possible for them, like monitoring of: rock-falling, micro seismic railway, infrastructures, and people movements.展开更多
One of the least selected contents by teachers of physical education （PE） in high school is the combat sport. Several authors have reported the neglect suffered by these activities in the Spanish school environment,...One of the least selected contents by teachers of physical education （PE） in high school is the combat sport. Several authors have reported the neglect suffered by these activities in the Spanish school environment, stating a number of social prejudices and beliefs that affect their selection in school, e.g., they are aggressive and dangerous. Fencing is usually not included for several reasons; lack of knowledge about sport, its complexity, the cost of practice materials, lack of teaching materials, and the limited researches. This paper presents the results of a survey of 106 PE teachers of Valencia （Spain） in order to know what are the main causes that affect the non-selection of fencing as a sport in school, with emphasis on the lack of training and materials, both specific in fencing＇s learning.展开更多
One of the goals of grazing management in the desert steppe is to improve its ecosystem.However,relatively little is known about soil microbe communities in the desert steppe ecosystem under grazing management.In this...One of the goals of grazing management in the desert steppe is to improve its ecosystem.However,relatively little is known about soil microbe communities in the desert steppe ecosystem under grazing management.In this study,we investigated the diversity and aboveground biomass of Caragana korshinskii Kom.shrub communities in long-term fencing and grazing areas,combined with an analysis of soil physical-chemical properties and genomics,with the aim of understanding how fence management affects plant-soil-microbial inter-relationships in the desert steppe,China.The results showed that fence management(exclosure)increased plant diversity and aboveground biomass in C.korshinskii shrub area and effectively enhanced soil organic carbon(233.94%),available nitrogen(87.77%),and available phosphorus(53.67%)contents.As well,the Shannon indices of soil bacteria and fungi were greater in the fenced plot.Plant-soil changes profoundly affected the alpha-and beta-diversity of soil bacteria.Fence management also altered the soil microbial community structure,significantly increasing the relative abundances of Acidobacteriota(5.31%-8.99%),Chloroflexi(3.99%-5.58%),and Glomeromycota(1.37%-3.28%).The soil bacterial-fungal co-occurrence networks under fence management had higher complexity and connectivity.Based on functional predictions,fence management significantly increased the relative abundance of bacteria with nitrification and nitrate reduction functions and decreased the relative abundance of bacteria with nitrate and nitrite respiration functions.The relative abundances of ecologically functional fungi with arbuscular mycorrhizal fungi,ectomycorrhizal fungi,and saprotrophs also significantly increased under fence management.In addition,the differential functional groups of bacteria and fungi were closely related to plant-soil changes.The results of this study have significant positive implications for the ecological restoration and reconstruction of dry desert steppe and similar areas.展开更多
Fencing is an important part of husbandry for pastoral communities;however, these same fences can have unintended consequences for wildlife populations by restricting movement, reducing connectivity, and causing direc...Fencing is an important part of husbandry for pastoral communities;however, these same fences can have unintended consequences for wildlife populations by restricting movement, reducing connectivity, and causing direct mortality. This paper assesses the current status and effects of fencing present in Yanchiwan National Nature Reserve, soon to be part of the recently proposed Qilianshan National Park. A questionnaire survey was conducted among 70 households to gauge local herders’ perceptions of fences, threats of fencing to native ungulates, and the number of wildlife found entangled in fencing. We found that local communities rely on fencing for livestock management and individuals who had encountered wildlife entangled in fences were more likely to perceive fences as having negative effects. Furthermore, those who perceived fencing as harmful to wildlife were more likely to support the dismantling of fences. On the other hand, families who needed to hire others to tend to their livestock were less likely to support dismantling efforts. However, the best model was only able to account for some of the data variability, suggesting that while perceptions of fences are important, other factors could be influencing support for fence dismantling. Hence, increasing awareness of threats alone may not be enough to generate community support of a fence dismantling program. Therefore, outreach and community collaboration to reduce the impacts of fence alterations upon livestock management will be necessary for a successful fence dismantling program within the new national park. Finally, those surveyed reported finding kiang, argali, and Tibetan gazelle dead in fences, with kiang found more often than the other two. This suggests that these three species may be more vulnerable to fence entanglement and that they are good targets for future studies and dismantling efforts.展开更多
Background:Revegetation is widely used in degraded grassland restoration.However,the responses of grassland plant and soil properties to fencing(FC)and grazing(GZ)remain poorly understood,especially the vegetation–so...Background:Revegetation is widely used in degraded grassland restoration.However,the responses of grassland plant and soil properties to fencing(FC)and grazing(GZ)remain poorly understood,especially the vegetation–soil coupling coordination(C_(d))mechanism.This study explored single and interactive responses of vegetation and soil properties under FC and GZ after revegetation.Methods:A field experiment with FC and GZ treatments was conducted in Loess Plateau reconstructed grassland,with degraded grassland as the control(CK).Plant and soil properties and C_(d) were analyzed using the analytic hierarchy process(AHP)and principal component analysis(PCA).Results:The order of soil comprehensive evaluation(SCE)was GZ>FC>CK,while that of vegetation comprehensive evaluation(VCE)was FC>GZ>CK.The C_(d) of CK was 0.39(mild imbalance),while the values of FC and GZ were 0.57 and 0.54,respectively(little coordination).The VCE/SCE of FC was 1.48(soil lag type),and the values of GZ and CK were 0.69 and 0.35,respectively(vegetation lag and vegetation loss type,respectively).Conclusions:Both GZ and FC improved C_(d) and facilitated recovery.However,degraded grasslands should be restored via moderate grazing for sustainable ecological and economic development.展开更多
In this paper,the authors study the cooperative target-fencing problem for n-dimensional systems and a target with a general trajectory.Without using the velocity of the vehicles,a position feedback control law is pro...In this paper,the authors study the cooperative target-fencing problem for n-dimensional systems and a target with a general trajectory.Without using the velocity of the vehicles,a position feedback control law is proposed to fence the general target into the convex hull formed by the vehicles.Specifically,the dynamics of each vehicle is described by a double-integrator system.Two potential functions are designed to guarantee connectivity preservation of the communication network and collision avoidance among the vehicles.The proposed approach can deal with a target whose trajectory is any twice continuously differentiable function of time.The effectiveness of the result is verified by a numerical example.展开更多
Human-wildlife conflict is one of the biggest conservation challenges throughout the world.Various conservation strategies have been employed to limit these impacts,but often they are not adequately monitored and thei...Human-wildlife conflict is one of the biggest conservation challenges throughout the world.Various conservation strategies have been employed to limit these impacts,but often they are not adequately monitored and their effectiveness assessed.Recently,electric fencing has been constructed as a means to mitigate humanwildlife conflict surrounding many Nepalese protected areas.To date,there are no other studies analyzing the cost effectiveness and efficacy of fencing for conservation.This study aims to examine the cost effectiveness of electric fencing in the eastern sector of Chitwan National Park,Nepal,where the fencing has recently been constructed.Great Indian one-horned rhinoceros（Rhinoceros unicornis）,wild boar（Sus scrofa）,Asian elephant（Elephas maximus）,and tiger（Panthera tigris） were the main wildlife species involved in human-wildlife conflict in the buffer zone area surrounding the park,where the fencing was deployed.Electric fencing was significantly effective in reducing crop damage by 78% and livestock depredation by 30%–60%.Human mortality was not reduced significantly in the study areas and continued at low levels.Our analysis suggested that total net present value of the cost of electric fence in Kagendramalli User Committee（KMUC） and Mrigakunja User Committee（MKUC） was 1 517 959 NPR（Nepalese Rupees,21 685 USD） and 3 530 075 NPR（50 429 USD） respectively up to the fiscal year 2009/10.Net present benefit in KMUC and MKUC was 16 301 105 NPR（232 872 USD） and 38 304 602 NPR（547 208 USD） respectively up to 2009/10.The cost-benefit ratio of electric fence up to base fiscal year 2009/10 in KMUC is 10.73,whereas MKUC is 10.85.These results illustrate that the electric fencing program is economically and socially beneficial in reducing human-wildlife conflict（crop damage and livestock depredation） around the protected areas where large mammals occur.展开更多
Regeneration of degraded grassland ecosystems is a significant issue in restoration ecology globally. To understand the effects of artificial management measures on alpine meadows, we surveyed topsoil properties inclu...Regeneration of degraded grassland ecosystems is a significant issue in restoration ecology globally. To understand the effects of artificial management measures on alpine meadows, we surveyed topsoil properties including moisture, organic carbon (SOC), nitrogen (N), and phosphorus (P) contents five years after fencing and fencing + reseeding management practices in a sandy meadow in the eastern Qinghai-Tibetan Plateau, northwestern China. Both the fencing and fencing + reseeding management practices significantly increased soil moisture storage, SOC, total N, available N, total P, and available P, as compared to the unmanaged control. Fencing plus reseeding was more effective than fencing alone for improving soil C, N, and P contents. These suggested that rehabilitation by reseeding and fencing generally had favorable effects on the soil properties in degraded sandy alpine meadows, and was an effective approach for restoration of degraded meadow ecosystems of the Qinghai-Tibetan Plateau.展开更多
Overgrazing is regarded as one of the key factors of vegetation and soil degradation in the arid and semi-arid regions of Northwest China.Grazing exclusion(GE)is one of the most common pathways used to restore degrade...Overgrazing is regarded as one of the key factors of vegetation and soil degradation in the arid and semi-arid regions of Northwest China.Grazing exclusion(GE)is one of the most common pathways used to restore degraded grasslands and to improve their ecosystem services.Nevertheless,there are still significant controversies concerning GE’s effects on grassland diversity as well as carbon(C)and nitrogen(N)storage.It remains poorly understood in the arid desert regions,whilst being essential for the sustainable use of grassland resources.To assess the effects of GE on community characteristics and C and N storage of desert plant community in the arid desert regions,we investigated the community structure and plant biomass,as well as C and N storage of plants and soil(0-100 cm depth)in short-term GE(three years)plots and adjacent long-term freely grazing(FG)plots in the areas of sagebrush desert in Northwest China,which are important both for spring-autumn seasonal pasture and for ecological conservation.Our findings indicated that GE was beneficial to the average height,coverage and aboveground biomass(including stems,leaves and inflorescences,and litter)of desert plant community,to the species richness and importance values of subshrubs and perennial herbs,and to the biomass C and N storage of aboveground parts(P<0.05).However,GE was not beneficial to the importance values of annual herbs,root/shoot ratio and total N concentration in the 0-5 and 5-10 cm soil layers(P<0.05).Additionally,the plant density,belowground biomass,and soil organic C concentration and C storage in the 0-100 cm soil layer could not be significantly changed by short-term GE(three years).The results suggest that,although GE was not beneficial for C sequestration in the sagebrush desert ecosystem,it is an effective strategy for improving productivity,diversity,and C and N storage of plants.As a result,GE can be used to rehabilitate degraded grasslands in the arid desert regions of Northwest China.展开更多
Whether climate change or anthropogenic activities play a more pivotal role in regulating vegetation growth on the Tibetan Plateau is still controversial.A better understanding on grassland changes at a fine scale may...Whether climate change or anthropogenic activities play a more pivotal role in regulating vegetation growth on the Tibetan Plateau is still controversial.A better understanding on grassland changes at a fine scale may provide important guidance for local government policy and grassland management.Using two of the most reliable satellite NDVI products(MODIS NDVI and SPOT NDVI),we evaluated the dynamic of grasslands in the Zhegucuo valley on the southern Tibetan Plateau from 2000 to 2020,and analyzed its driving factors and relative influences of climate change and anthropogenic activities.Here,the key indicators of climate change were assumed to be precipitation and temperature.The main results were:(1)the grassland NDVI in Zhegucuo valley did not reflect a significant temporal change during the last 21 years.The variation of precipitation during the early growing season(GSP)resembled that of NDVI,and the GSP was positively correlated with NDVI.At the pixel level,the partial correlation analysis showed that 37.79%of the pixels depicted a positive relationship between GSP and NDVI,while 11.32%of the pixels showed a negative relationship between temperature during the early growing season(GST)and NDVI.(2)In view of the spatial distribution,the areas mainly controlled by GSP were generally distributed in the southern part,while those affected by GST stood in the eastern part,mainly around the Zhegucuo lake where most population in Cuomei County settled down.(3)Decreasing NDVI trends were mainly occurred in alpine steppe at lower elevations rather than alpine meadow at higher elevations.(4)The residual trend(RESTREND)analysis further indicated that the anthropogenic activities played a more pivotal role in regulating the annual changes of NDVI rather than climate factors in this area.Future studies should pay more attention on climate extremes rather than the simple temporal trends.Also,the influence of human activities on alpine grassland needs to be accessed and fully considered in future sustainable management.展开更多
A set of model is established to optimize BSW Company’s component stock. By analyzing the company’s current part stock condition in terms of the occupation of capitals in the precondition of continuous production, i...A set of model is established to optimize BSW Company’s component stock. By analyzing the company’s current part stock condition in terms of the occupation of capitals in the precondition of continuous production, it describes how to control the purchase parameters of import parts. The model describes how to adjust slightly product output sequence and how to control the components’ purchase parameters: purchasing risk time and purchase order quantity. Then simulation is developed to illustrate the model.展开更多
Perennial grass-legume mixtures have been extensively used to restore degraded grasslands,increasing grassland productivity and forage quality.Tillage is crucial for seedbed preparation and sustainable weed management...Perennial grass-legume mixtures have been extensively used to restore degraded grasslands,increasing grassland productivity and forage quality.Tillage is crucial for seedbed preparation and sustainable weed management for the establishment of grass-legume mixtures.However,a common concern is that intensive tillage may alter soil characteristics,leading to losses in soil organic carbon(SOC).We investigated the plant community composition,SOC,soil microbial biomass carbon(MBC),soil enzyme activities,and soil properties in long-term perennial grass-legume mixtures under two different tillage intensities(once and twice)as well as in a fenced grassland(FG).The establishment of grass-legume mixtures increased plant species diversity and plant community coverage,compared with FG.Compared with once tilled grassland(OTG),twice tilled grassland(TTG)enhanced the coverage of high-quality leguminous forage species by 380.3%.Grass-legume mixtures with historical tillage decreased SOC and dissolved organic carbon(DOC)concentrations,whereas soil MBC concentrations in OTG and TTG increased by 16.0%and 16.4%,respectively,compared with FG.TTG significantly decreased the activity of N-acetyl-β-D-glucosaminidase(NAG)by 72.3%,whereas soil enzymeβ-glucosidase(βG)in OTG and TTG increased by 55.9%and 27.3%,respectively,compared with FG.Correlation analysis indicated a close association of the increase in MBC andβG activities with the rapid decline in SOC.This result suggested that MBC was a key driving factor in soil carbon storage dynamics,potentially accelerating soil carbon cycling and facilitating biogeochemical cycling.The establishment of grass-legume mixtures effectively improves forage quality and boosts plant diversity,thereby facilitating the restoration of degraded grasslands.Although tillage assists in establishing legume-grass mixtures by controlling weeds,it accelerates microbial activity and organic carbon decomposition.Our findings provide a foundation for understanding the process and effectiveness of restoration management in degraded grasslands.展开更多
Desertification is one of the most serious environmental problems in the world,especially in the arid desert regions.Combating desertification,therefore,is an urgent task on a regional or even global scale.The Taklima...Desertification is one of the most serious environmental problems in the world,especially in the arid desert regions.Combating desertification,therefore,is an urgent task on a regional or even global scale.The Taklimakan Desert in China is the second largest mobile desert in the world and has been called the''Dead Sea''due to few organisms can exist in such a harsh environment.The Taklimakan Desert Highway,the longest desert highway(a total length of 446 km)across the mobile desert in the world,was built in the 1990s within the Taklimakan Desert.It has an important strategic significance regarding oil and gas resources exploration and plays a vital role in the socio-economic development of southern Xinjiang,China.However,wind-blow sand seriously damages the smoothness of the desert highway and,in this case,mechanical sand control system(including sand barrier fences and straw checkerboards)was used early in the life of the desert highway to protect the road.Unfortunately,more than 70%of the sand barrier fences and straw checkerboards have lost their functions,and the desert highway has often been buried and frequently blocked since 1999.To solve this problem,a long artificial shelterbelt with the length of 437 km was built along the desert highway since 2000.However,some potential problems still exist for the sustainable development of the desert highway,such as water shortage,strong sandstorms,extreme environmental characteristics and large maintenance costs.The study aims to provide an overview of the damages caused by wind-blown sand and the effects of sand control measures along the Taklimakan Desert Highway.Ultimately,we provide some suggestions for the biological sand control system to ensure the sustainable development of the Taklimakan Desert Highway,such as screening drought-resistant species to reduce the irrigation requirement and ensure the sound development of groundwater,screening halophytes to restore vegetation in the case of soil salinization,and planting cash crops,such as Cistanche,Wolfberry,Apocynum and other cash crops to decrease the high cost of maintenance on highways and shelterbelts.展开更多
文摘This paper proposes a distributed event-triggered control(ETC)framework to address cooperative target fencing challenges in UAV swarm.The proposed architecture eliminates the reliance on preset formation parameters while achieving multi-objective cooperative control for target fencing,network connectivity preservation,collision avoidance,and communication efficiency optimization.Firstly,a differential state observer is constructed to obtain the target's unmeasurable states.Secondly,leveraging swarm selforganization principles,a geometric-constraint-free distributed fencing controller is designed by integrating potential field methods with consensus theory.The controller dynamically adjusts inter-UAV distances via single potential function,enabling coordinated optimization of persistent network connectivity and collision-free motion during target fencing.Thirdly,a dual-threshold ETC mechanism based on velocity consensus deviation and fencing error is proposed,which can be triggered based on task features to dynamically adjust the communication frequency,significantly reduce the communication burden and exclude Zeno behavior.Theoretical analysis demonstrates the stability of closed-loop systems.Multi-scenario simulations show that the proposed method can achieve robust fencing under target maneuverability,partial UAV failures,and communication disturbances.
基金supported by the National Key Basic Research Program of China (2011CB403203)the Strategic Science and Technology Guide Project of Chinese Academy of Sciences (XDA05050401)
文摘In order to restore a degraded alkaline grassland, the local government implemented a large restoration project using fences in Changling county, Jilin province, China, in 2000. Grazing was excluded from the protected area, whereas the grazed area was continuously grazed at 8.5 dry sheep equivalent（DSE）/hm2. In the current research, soil and plant samples were taken from grazed and fenced areas to examine changes in vegetation and soil properties in 2005, 2006 and 2008. Results showed that vegetation characteristics and soil properties improved significantly in the fenced area compared with the grazed area. In the protected area the vegetation cover, height and above- and belowground biomass increased significantly. Soil pH, electrical conductivity and bulk density decreased significantly, but soil organic carbon and total nitrogen concentration increased greatly in the protected area. By comparing the vegetation and soil characteristics with pre-degraded grassland, we found that vegetation can recover 6 years after fencing, and soil pH can be restored 8 years after fencing. However, the restoration of soil organic carbon, total nitrogen and total phosphorus concentrations needed 16, 30 and 19 years, respectively. It is recommended that the stocking rate should be reduced to 1/3 of the current carrying capacity, or that a grazing regime of 1-year of grazing followed by a 2-year rest is adopted to sustain the current status of vegetation and soil resources. However, if N fertilizer is applied, the rest period could be shortened, depending on the rate of application.
基金supported by the Natural Science Foundation Committee of China(41230750 and 41101081)Key Program of the Chinese Academy of Sciences(KFZD-SW-312)the"National Key Research and Development Program of China"(2016YFC0501802)
文摘Fencing is the most common land-management practice to protect grassland degradation from livestock overgrazing on the Tibetan Plateau.However,it is unclear whether fencing reduces CO_(2),CH_4,and N_2O emission.Here,we selected four vegetation types of alpine meadow(graminoid,shrub,forb,and sparse vegetation)to determine fencing effects on ecosystem respiration(Re),CH_4,and N_2O fluxes during the growing season.Despite increased average monthly ecosystem respiration(Re)for fenced graminoid vegetation at the end of the growing season,there was no significant difference between grazing and fencing across all vegetation types.Fencing significantly reduced average CH_4 uptake by about 50%in 2008 only for forb vegetation and increased average N_2O release for graminoid vegetation by 38%and 48%in 2008 and 2009,respectively.Temperature,moisture,total organic carbon,C/N,nitrate,ammonia,and/or bulk density of soil,as well as above-and belowground biomass,explained 19%~71%and 6%~33%of variation in daily and average Re and CH_4 fluxes across all vegetation types,while soil-bulk density explained 27%of variation in average N_2O fluxes.Stepwise regression showed that soil temperature and soil moisture controlled average Re,while soil moisture and bulk density controlled average CH_4 fluxes.These results indicate that abiotic factors control Re,CH_4,and N_2O fluxes;and grazing exclusion has little effect on reducing their emission—implying that climatic change rather than grazing may have a more important influence on the budgets of Re and CH_4 for the Tibetan alpine meadow during the growing season.
文摘To avoid wildlife-human conflict several solutions are used, like electrical fences, the most expensive solution. Nowadays, technology enables alternative and cheaper approaches for conservation projects. A technological device was developed to detect elephants, moving on their habitat, and predict and react by avoiding confrontation with man. The devices were tested in field experiments, and proved to be efficient in capturing floor vibration, and air-sound signals. Collected data also enabled the estimation of the vibration-source by calculus (using triangulation), revealing the importance of the methodology for real-time location and tracking of high mass animals (e.g. elephants). Building up a mesh of devices, separated 25 m from each other, is estimated as possible to monitor and identify different animals (by discriminating patterns) in an area, like a virtual fencing system. Though the devices may be effective for animal behaviour research, or even animal communication analysis, or other Biology field, other applications outside Biology are possible for them, like monitoring of: rock-falling, micro seismic railway, infrastructures, and people movements.
文摘One of the least selected contents by teachers of physical education （PE） in high school is the combat sport. Several authors have reported the neglect suffered by these activities in the Spanish school environment, stating a number of social prejudices and beliefs that affect their selection in school, e.g., they are aggressive and dangerous. Fencing is usually not included for several reasons; lack of knowledge about sport, its complexity, the cost of practice materials, lack of teaching materials, and the limited researches. This paper presents the results of a survey of 106 PE teachers of Valencia （Spain） in order to know what are the main causes that affect the non-selection of fencing as a sport in school, with emphasis on the lack of training and materials, both specific in fencing＇s learning.
基金funded by the National Natural Science Foundation of China(32061123006,32360426).
文摘One of the goals of grazing management in the desert steppe is to improve its ecosystem.However,relatively little is known about soil microbe communities in the desert steppe ecosystem under grazing management.In this study,we investigated the diversity and aboveground biomass of Caragana korshinskii Kom.shrub communities in long-term fencing and grazing areas,combined with an analysis of soil physical-chemical properties and genomics,with the aim of understanding how fence management affects plant-soil-microbial inter-relationships in the desert steppe,China.The results showed that fence management(exclosure)increased plant diversity and aboveground biomass in C.korshinskii shrub area and effectively enhanced soil organic carbon(233.94%),available nitrogen(87.77%),and available phosphorus(53.67%)contents.As well,the Shannon indices of soil bacteria and fungi were greater in the fenced plot.Plant-soil changes profoundly affected the alpha-and beta-diversity of soil bacteria.Fence management also altered the soil microbial community structure,significantly increasing the relative abundances of Acidobacteriota(5.31%-8.99%),Chloroflexi(3.99%-5.58%),and Glomeromycota(1.37%-3.28%).The soil bacterial-fungal co-occurrence networks under fence management had higher complexity and connectivity.Based on functional predictions,fence management significantly increased the relative abundance of bacteria with nitrification and nitrate reduction functions and decreased the relative abundance of bacteria with nitrate and nitrite respiration functions.The relative abundances of ecologically functional fungi with arbuscular mycorrhizal fungi,ectomycorrhizal fungi,and saprotrophs also significantly increased under fence management.In addition,the differential functional groups of bacteria and fungi were closely related to plant-soil changes.The results of this study have significant positive implications for the ecological restoration and reconstruction of dry desert steppe and similar areas.
基金The National Natural Science Foundation of China (31470567)。
文摘Fencing is an important part of husbandry for pastoral communities;however, these same fences can have unintended consequences for wildlife populations by restricting movement, reducing connectivity, and causing direct mortality. This paper assesses the current status and effects of fencing present in Yanchiwan National Nature Reserve, soon to be part of the recently proposed Qilianshan National Park. A questionnaire survey was conducted among 70 households to gauge local herders’ perceptions of fences, threats of fencing to native ungulates, and the number of wildlife found entangled in fencing. We found that local communities rely on fencing for livestock management and individuals who had encountered wildlife entangled in fences were more likely to perceive fences as having negative effects. Furthermore, those who perceived fencing as harmful to wildlife were more likely to support the dismantling of fences. On the other hand, families who needed to hire others to tend to their livestock were less likely to support dismantling efforts. However, the best model was only able to account for some of the data variability, suggesting that while perceptions of fences are important, other factors could be influencing support for fence dismantling. Hence, increasing awareness of threats alone may not be enough to generate community support of a fence dismantling program. Therefore, outreach and community collaboration to reduce the impacts of fence alterations upon livestock management will be necessary for a successful fence dismantling program within the new national park. Finally, those surveyed reported finding kiang, argali, and Tibetan gazelle dead in fences, with kiang found more often than the other two. This suggests that these three species may be more vulnerable to fence entanglement and that they are good targets for future studies and dismantling efforts.
基金National Natural Science Foundation of China,Grant/Award Number:42041005。
文摘Background:Revegetation is widely used in degraded grassland restoration.However,the responses of grassland plant and soil properties to fencing(FC)and grazing(GZ)remain poorly understood,especially the vegetation–soil coupling coordination(C_(d))mechanism.This study explored single and interactive responses of vegetation and soil properties under FC and GZ after revegetation.Methods:A field experiment with FC and GZ treatments was conducted in Loess Plateau reconstructed grassland,with degraded grassland as the control(CK).Plant and soil properties and C_(d) were analyzed using the analytic hierarchy process(AHP)and principal component analysis(PCA).Results:The order of soil comprehensive evaluation(SCE)was GZ>FC>CK,while that of vegetation comprehensive evaluation(VCE)was FC>GZ>CK.The C_(d) of CK was 0.39(mild imbalance),while the values of FC and GZ were 0.57 and 0.54,respectively(little coordination).The VCE/SCE of FC was 1.48(soil lag type),and the values of GZ and CK were 0.69 and 0.35,respectively(vegetation lag and vegetation loss type,respectively).Conclusions:Both GZ and FC improved C_(d) and facilitated recovery.However,degraded grasslands should be restored via moderate grazing for sustainable ecological and economic development.
基金supported in part by the Research Grants Council of Hong Kong SAR under Grant Nos.14206821 and 14217922in part by the Hong Kong Centre For Logistics Robotics (HKCLR)
文摘In this paper,the authors study the cooperative target-fencing problem for n-dimensional systems and a target with a general trajectory.Without using the velocity of the vehicles,a position feedback control law is proposed to fence the general target into the convex hull formed by the vehicles.Specifically,the dynamics of each vehicle is described by a double-integrator system.Two potential functions are designed to guarantee connectivity preservation of the communication network and collision avoidance among the vehicles.The proposed approach can deal with a target whose trajectory is any twice continuously differentiable function of time.The effectiveness of the result is verified by a numerical example.
基金supported by National Trust for Nature Conservation,Nepal
文摘Human-wildlife conflict is one of the biggest conservation challenges throughout the world.Various conservation strategies have been employed to limit these impacts,but often they are not adequately monitored and their effectiveness assessed.Recently,electric fencing has been constructed as a means to mitigate humanwildlife conflict surrounding many Nepalese protected areas.To date,there are no other studies analyzing the cost effectiveness and efficacy of fencing for conservation.This study aims to examine the cost effectiveness of electric fencing in the eastern sector of Chitwan National Park,Nepal,where the fencing has recently been constructed.Great Indian one-horned rhinoceros（Rhinoceros unicornis）,wild boar（Sus scrofa）,Asian elephant（Elephas maximus）,and tiger（Panthera tigris） were the main wildlife species involved in human-wildlife conflict in the buffer zone area surrounding the park,where the fencing was deployed.Electric fencing was significantly effective in reducing crop damage by 78% and livestock depredation by 30%–60%.Human mortality was not reduced significantly in the study areas and continued at low levels.Our analysis suggested that total net present value of the cost of electric fence in Kagendramalli User Committee（KMUC） and Mrigakunja User Committee（MKUC） was 1 517 959 NPR（Nepalese Rupees,21 685 USD） and 3 530 075 NPR（50 429 USD） respectively up to the fiscal year 2009/10.Net present benefit in KMUC and MKUC was 16 301 105 NPR（232 872 USD） and 38 304 602 NPR（547 208 USD） respectively up to 2009/10.The cost-benefit ratio of electric fence up to base fiscal year 2009/10 in KMUC is 10.73,whereas MKUC is 10.85.These results illustrate that the electric fencing program is economically and socially beneficial in reducing human-wildlife conflict（crop damage and livestock depredation） around the protected areas where large mammals occur.
基金Supported by the Strategic and Leading Sci-Tech Project of the Chinese Academy of Sciences (No.XDA05050403)the Key Laboratory of Arid and Grassland Ecology of the Ministry of Education, Lanzhou University, China, the State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, China (Nos.10502-Z8-5 and 10502-Z12)the Hundred Talents Program of the Chinese Academy of Sciences
文摘Regeneration of degraded grassland ecosystems is a significant issue in restoration ecology globally. To understand the effects of artificial management measures on alpine meadows, we surveyed topsoil properties including moisture, organic carbon (SOC), nitrogen (N), and phosphorus (P) contents five years after fencing and fencing + reseeding management practices in a sandy meadow in the eastern Qinghai-Tibetan Plateau, northwestern China. Both the fencing and fencing + reseeding management practices significantly increased soil moisture storage, SOC, total N, available N, total P, and available P, as compared to the unmanaged control. Fencing plus reseeding was more effective than fencing alone for improving soil C, N, and P contents. These suggested that rehabilitation by reseeding and fencing generally had favorable effects on the soil properties in degraded sandy alpine meadows, and was an effective approach for restoration of degraded meadow ecosystems of the Qinghai-Tibetan Plateau.
基金This work was supported by the National Basic Resources Survey Project of China(2017FY100201)the Grassology Peak Discipline Foundation of Xinjiang Uygur Autonomous Region,China(CXGFXK-2019-01).
文摘Overgrazing is regarded as one of the key factors of vegetation and soil degradation in the arid and semi-arid regions of Northwest China.Grazing exclusion(GE)is one of the most common pathways used to restore degraded grasslands and to improve their ecosystem services.Nevertheless,there are still significant controversies concerning GE’s effects on grassland diversity as well as carbon(C)and nitrogen(N)storage.It remains poorly understood in the arid desert regions,whilst being essential for the sustainable use of grassland resources.To assess the effects of GE on community characteristics and C and N storage of desert plant community in the arid desert regions,we investigated the community structure and plant biomass,as well as C and N storage of plants and soil(0-100 cm depth)in short-term GE(three years)plots and adjacent long-term freely grazing(FG)plots in the areas of sagebrush desert in Northwest China,which are important both for spring-autumn seasonal pasture and for ecological conservation.Our findings indicated that GE was beneficial to the average height,coverage and aboveground biomass(including stems,leaves and inflorescences,and litter)of desert plant community,to the species richness and importance values of subshrubs and perennial herbs,and to the biomass C and N storage of aboveground parts(P<0.05).However,GE was not beneficial to the importance values of annual herbs,root/shoot ratio and total N concentration in the 0-5 and 5-10 cm soil layers(P<0.05).Additionally,the plant density,belowground biomass,and soil organic C concentration and C storage in the 0-100 cm soil layer could not be significantly changed by short-term GE(three years).The results suggest that,although GE was not beneficial for C sequestration in the sagebrush desert ecosystem,it is an effective strategy for improving productivity,diversity,and C and N storage of plants.As a result,GE can be used to rehabilitate degraded grasslands in the arid desert regions of Northwest China.
基金funded by the Second Tibetan Plateau Scientific Expedition and Research program(2019QZKK0301)the Natural Science Foundation of Xizang Autonomous Region(XZ202301ZR0027G).
文摘Whether climate change or anthropogenic activities play a more pivotal role in regulating vegetation growth on the Tibetan Plateau is still controversial.A better understanding on grassland changes at a fine scale may provide important guidance for local government policy and grassland management.Using two of the most reliable satellite NDVI products(MODIS NDVI and SPOT NDVI),we evaluated the dynamic of grasslands in the Zhegucuo valley on the southern Tibetan Plateau from 2000 to 2020,and analyzed its driving factors and relative influences of climate change and anthropogenic activities.Here,the key indicators of climate change were assumed to be precipitation and temperature.The main results were:(1)the grassland NDVI in Zhegucuo valley did not reflect a significant temporal change during the last 21 years.The variation of precipitation during the early growing season(GSP)resembled that of NDVI,and the GSP was positively correlated with NDVI.At the pixel level,the partial correlation analysis showed that 37.79%of the pixels depicted a positive relationship between GSP and NDVI,while 11.32%of the pixels showed a negative relationship between temperature during the early growing season(GST)and NDVI.(2)In view of the spatial distribution,the areas mainly controlled by GSP were generally distributed in the southern part,while those affected by GST stood in the eastern part,mainly around the Zhegucuo lake where most population in Cuomei County settled down.(3)Decreasing NDVI trends were mainly occurred in alpine steppe at lower elevations rather than alpine meadow at higher elevations.(4)The residual trend(RESTREND)analysis further indicated that the anthropogenic activities played a more pivotal role in regulating the annual changes of NDVI rather than climate factors in this area.Future studies should pay more attention on climate extremes rather than the simple temporal trends.Also,the influence of human activities on alpine grassland needs to be accessed and fully considered in future sustainable management.
文摘A set of model is established to optimize BSW Company’s component stock. By analyzing the company’s current part stock condition in terms of the occupation of capitals in the precondition of continuous production, it describes how to control the purchase parameters of import parts. The model describes how to adjust slightly product output sequence and how to control the components’ purchase parameters: purchasing risk time and purchase order quantity. Then simulation is developed to illustrate the model.
基金funded by the National Natural Science Foundation of China(32271776,32171616)the Special Sichuan Postdoctoral Research Projectsthe National Natural Science Foundation of Sichuan Province,China(2024NSFSC0309,2022NSFSC1769,2022NSFSC0110).
文摘Perennial grass-legume mixtures have been extensively used to restore degraded grasslands,increasing grassland productivity and forage quality.Tillage is crucial for seedbed preparation and sustainable weed management for the establishment of grass-legume mixtures.However,a common concern is that intensive tillage may alter soil characteristics,leading to losses in soil organic carbon(SOC).We investigated the plant community composition,SOC,soil microbial biomass carbon(MBC),soil enzyme activities,and soil properties in long-term perennial grass-legume mixtures under two different tillage intensities(once and twice)as well as in a fenced grassland(FG).The establishment of grass-legume mixtures increased plant species diversity and plant community coverage,compared with FG.Compared with once tilled grassland(OTG),twice tilled grassland(TTG)enhanced the coverage of high-quality leguminous forage species by 380.3%.Grass-legume mixtures with historical tillage decreased SOC and dissolved organic carbon(DOC)concentrations,whereas soil MBC concentrations in OTG and TTG increased by 16.0%and 16.4%,respectively,compared with FG.TTG significantly decreased the activity of N-acetyl-β-D-glucosaminidase(NAG)by 72.3%,whereas soil enzymeβ-glucosidase(βG)in OTG and TTG increased by 55.9%and 27.3%,respectively,compared with FG.Correlation analysis indicated a close association of the increase in MBC andβG activities with the rapid decline in SOC.This result suggested that MBC was a key driving factor in soil carbon storage dynamics,potentially accelerating soil carbon cycling and facilitating biogeochemical cycling.The establishment of grass-legume mixtures effectively improves forage quality and boosts plant diversity,thereby facilitating the restoration of degraded grasslands.Although tillage assists in establishing legume-grass mixtures by controlling weeds,it accelerates microbial activity and organic carbon decomposition.Our findings provide a foundation for understanding the process and effectiveness of restoration management in degraded grasslands.
基金This work was supported by the National Natural Science Foundation of China(31971731,41771121)the Xinjiang National Key Research and Development Program(2019B00005)+1 种基金the National Key Research and Development Program(2017YFC0506705)the Youth Innovation Promotion Association of Chinese Academy of Sciences(2017476).
文摘Desertification is one of the most serious environmental problems in the world,especially in the arid desert regions.Combating desertification,therefore,is an urgent task on a regional or even global scale.The Taklimakan Desert in China is the second largest mobile desert in the world and has been called the''Dead Sea''due to few organisms can exist in such a harsh environment.The Taklimakan Desert Highway,the longest desert highway(a total length of 446 km)across the mobile desert in the world,was built in the 1990s within the Taklimakan Desert.It has an important strategic significance regarding oil and gas resources exploration and plays a vital role in the socio-economic development of southern Xinjiang,China.However,wind-blow sand seriously damages the smoothness of the desert highway and,in this case,mechanical sand control system(including sand barrier fences and straw checkerboards)was used early in the life of the desert highway to protect the road.Unfortunately,more than 70%of the sand barrier fences and straw checkerboards have lost their functions,and the desert highway has often been buried and frequently blocked since 1999.To solve this problem,a long artificial shelterbelt with the length of 437 km was built along the desert highway since 2000.However,some potential problems still exist for the sustainable development of the desert highway,such as water shortage,strong sandstorms,extreme environmental characteristics and large maintenance costs.The study aims to provide an overview of the damages caused by wind-blown sand and the effects of sand control measures along the Taklimakan Desert Highway.Ultimately,we provide some suggestions for the biological sand control system to ensure the sustainable development of the Taklimakan Desert Highway,such as screening drought-resistant species to reduce the irrigation requirement and ensure the sound development of groundwater,screening halophytes to restore vegetation in the case of soil salinization,and planting cash crops,such as Cistanche,Wolfberry,Apocynum and other cash crops to decrease the high cost of maintenance on highways and shelterbelts.
