This study attempted to compare the performance of local polynomial interpolation,inverse distance weighted interpolation,and ordinary kriging in studying distribution patterns of swimming crabs.Cross-validation was u...This study attempted to compare the performance of local polynomial interpolation,inverse distance weighted interpolation,and ordinary kriging in studying distribution patterns of swimming crabs.Cross-validation was used to select the optimum method to get distribution results,and kriging was used for making spatial variability analysis.Data were collected from 87 sampling stations in November of 2015(autumn)and February(winter),May(spring)and August(summer)of 2016.Results indicate that swimming crabs widely distributed in autumn and summer:in the summer,they were more spatially independent,and resources in each sampling station varied a lot;in the winter and spring,the abundance of crabs was much lower,but the individual crab size was bigger,and they showed the patchy and more concentrative distribution pattern,which means they were more spatially dependent.Distribution patterns were in accordance with ecological migration features of swimming crabs,which were affected by the changing marine environment.This study could infer that it is applicable to study crab fishery or even other crustacean species using geostatistical analysis.It not only helps practitioners have a better understanding of how swimming crabs migrate from season to season,but also assists researchers in carrying out a more comprehensive assessment of the fishery.Therefore,it may facilitate advancing the implementation in the pilot quota management program of swimming crabs in northern Zhejiang fishing grounds.展开更多
Tajikistan represents a core region of the biodiversity hotspot in Central Asian mountains and has exceptional vascular plant diversity.However,the species diversity of the country faces urgent conservation challenges...Tajikistan represents a core region of the biodiversity hotspot in Central Asian mountains and has exceptional vascular plant diversity.However,the species diversity of the country faces urgent conservation challenges.There has been a lack of a comprehensive and multidimensional assessment to inform strategic conservation planning.Therefore,this study integrated 4 key biodiversity indices including species richness(SR),phylogenetic diversity(PD),threatened species richness(TSR),and endemic species richness(ESR)to map species diversity distribution patterns,identify conservation gaps,and elucidate their effects of climatic factors.This study revealed that species diversity shows a clear trend of decreasing from the western region to the eastern region of Tajikistan.The central–western mountains(specifically the Gissar-Darvasian and Zeravshanian regions)emerge as irreplaceable biodiversity hotspots.However,we found a severe spatial mismatch between these priority areas and the existing protected areas(PAs).Protection coverage for all hotspots was alarmingly low,ranging from 31.00%to 38.00%.Consequently,a critical 64.80%of integrated priority areas fall outside of the current PAs,representing a major conservation gap.This study identified precipitation seasonality and isothermality as the principal drivers,collectively explaining over 50.00%of the diversity variation and suggesting high vulnerability to hydrological shifts.Furthermore,we detected significant geographic sampling bias in the public biodiversity databases,with the most critical hotspot being systematically under-sampled.This study provides a robust scientific basis for conservation action,highlighting the urgent need to strategically expand PAs in the under-protected southwestern region and to mitigate critical sampling gaps through targeted data digitization and field surveys.These measures are indispensable for securing Tajikistan’s unique biodiversity and achieving the Kunming-Montreal Global Biodiversity Framework Target 3(“30×30 Protection”).展开更多
An improved Carnegie Ames Stanford Approach model （CASA model） was used to estimate the net primary productivity （NPP） of the Northeast China Transect （NECT） every month from 1982 to 2000. The spatial-temporal d...An improved Carnegie Ames Stanford Approach model （CASA model） was used to estimate the net primary productivity （NPP） of the Northeast China Transect （NECT） every month from 1982 to 2000. The spatial-temporal distribution of NPP along NECT and its response to climatic change were also analyzed. Results showed that the change tendency of NPP spatial distribution in NECT is quite similar to that of precipitation and their spatial correlation coefficient is up to 0.84 （P 〈 0.01）. The inter-annual variation of NPP in NECT is mainly affected by the change of the aestival NPP every year, which accounts for 67.6% of the inter-annual increase in NPP and their spatial correlation coefficient is 0.95 （P 〈 0.01）. The NPP in NECT is mainly cumulated between May and September, which accounts for 89.8% of the annual NPP. The NPP in summer （June to August） accounts for 65.9% of the annual NPP and is the lowest in winter. Recent climate changes have enhanced plant growth in NECT. The mean NPP increased 14.3% from 1980s to 1990s. The inter-annual linear trend of NPP is 4.6 gC·m^-2·a^-1, and the relative trend is 1.17%, which owns mainly to the increasing temperature.展开更多
The cloud-to-ground lightning data between 2007 and 2008 were collected by lightning detection and location system,which was composed of four lightning detectors in four different sites of Dalian area.The spatio-tempo...The cloud-to-ground lightning data between 2007 and 2008 were collected by lightning detection and location system,which was composed of four lightning detectors in four different sites of Dalian area.The spatio-temporal distribution of cloud-to-ground lightning in surrounding areas of Dalian was analyzed from several aspects of polarity distribution,diurnal variation,lightning intensity and lightning density.The results showed that the number of negative lightning accounted for 93.9% of the total number of lightning,and its average lightning intensity was 27.99 kA.The number of positive lightning accounted for 6.1% of the total number of lightning,and its average lightning intensity was 35.56 kA.The diurnal variation of lightning frequency showed an obvious structure of two peaks (17:00-18:00 and 04:00-05:00) and two valleys (09:00-10:00 and 00:00-01:00).The number of lightning between May and September was 91.5% of the annual number,and the lightning occurred the most frequently between June and August.Most of positive and negative lightning was at the intensity of 15-35 kA,80.0% lower than 40 kA,and 99.3% lower than 100 kA.The lightning density had obvious regional differences in distribution,high in the Liaodong Bay and the Dalian Bay and low in inland areas.Therefore,coastal areas should attract more attention in lightning disaster defense in the surrounding areas of Dalian.展开更多
Climate change disrupts the distribution of species and restructures their richness patterns.The genus of Asian bamboo,Phyllostachys,possesses significant ecological and economic values,and represents the most species...Climate change disrupts the distribution of species and restructures their richness patterns.The genus of Asian bamboo,Phyllostachys,possesses significant ecological and economic values,and represents the most speciesrich genus in the Bambusoideae subfamily.Based on the distribution data of 46 species and 20 environmental variables,we used the MaxEnt model combined with ArcGIS calculations to simulate current and future potential richness distributions under three distinct CO_(2) emission scenarios.The results showed that the MaxEnt model had a good predictive ability,with a mean area under the working characteristic curve(AUC value)of 0.91 for all species.The main environmental variables that impacted the future distribution of most Phyllostachys species were elevation,variations of seasonal precipitation,and mean diurnal range.Phyllostachys species are currently concentrated in southeastern China.Under future climate projections,18 species exhibited significant habitat contraction across three or more future climate scenarios,but suitable habitats for other species will expand.This enhancement is most pronounced under the extreme climate scenario(2090s-SSP585),primarily driven by high species gains contributing to elevated turnover values across scenarios.The center of maximum richness will progressively shift southwestward over time.Predictive modeling of Phyllostachys richness distribution dynamics under climate change enhances our understanding of its biogeography and informs strategic introduction programs to bamboo management and augments China’s carbon sequestration capacity.展开更多
The isolated fracture-vug systems controlled by small-scale strike-slip faults within ultra-deep carbonate rocks of the Tarim Basin exhibit significant exploration potential.The study employs a novel training set inco...The isolated fracture-vug systems controlled by small-scale strike-slip faults within ultra-deep carbonate rocks of the Tarim Basin exhibit significant exploration potential.The study employs a novel training set incorporating innovative fault labels to train a U-Net-structured CNN model,enabling effective identification of small-scale strike-slip faults through seismic data interpretation.Based on the CNN faults,we analyze the distribution patterns of small-scale strike-slip faults.The small-scale strike-slip faults can be categorized into NNW-trending and NE-trending groups with strike lengths ranging 200–5000 m.The development intensity of small-scale strike-slip faults in the Lower Yingshan Member notably exceeds that in the Upper Member.The Lower and Upper Yingshan members are two distinct mechanical layers with contrasting brittleness characteristics,separated by a low-brittleness layer.The superior brittleness of the Lower Yingshan Member enhances the development intensity of small-scale strike-slip faults compared to the upper member,while the low-brittleness layer exerts restrictive effects on vertical fault propagation.Fracture-vug systems formed by interactions of two or more small-scale strike-slip faults demonstrate larger sizes than those controlled by individual faults.All fracture-vug system sizes show positive correlations with the vertical extents of associated small-scale strike-slip faults,particularly intersection and approaching fracture-vug systems exhibit accelerated size increases proportional to the vertical extents.展开更多
Landforms are an important factor determining the spatial pattern of cropland through allocation of surface water and heat. Therefore, it is of great importance to study the change in cropland distribution from the pe...Landforms are an important factor determining the spatial pattern of cropland through allocation of surface water and heat. Therefore, it is of great importance to study the change in cropland distribution from the perspective of geomorphologic divisions. Based on China's multi-year land cover data(1990, 1995, 2000, 2005, 2010 and 2015) and geomorphologic regionalization data, we analyzed the change in cropland area and its distribution pattern in six geomorphologic regions of China over the period of 1990-2015 with the aid of GIS techniques. Our results showed that the total cropland area increased from 177.1 to 178.5 million ha with an average increase rate of 0.03%. Cropland area decreased in southern China and increased in northern China. Region I(Eastern hilly plains) had the highest cropland increase rate, while the cropland dynamic degree of Region IV(Northwestern middle and high mountains, basins and plateaus) was significantly higher than that of other regions. The barycenter of China's cropland shifted from northern China to the northwest over the 25-year period. Regions IV and I were the two regions with the greatest increase of cropland. Region II(Southeastern low and middle mountains) and Region V(Southwestern middle and low mountains, plateaus and basins) were the main decreasing cropland regions. The area of cropland remained almost unchanged in Region III(Northern China and Inner Mongolia eastern-central mountains and plateaus) and Region VI(Tibetan Plateau). The loss of cropland occurred mostly in Regions I and II as a result of growing industrialization and urbanization, while the increase of cropland occurred mainly in Region IV because of reclamation of grassland and other wasteland. These analyzing results would provide fundamental information for further studies of urban planning, ecosystem management, and natural resourcesconservation in China.展开更多
Macrobenthic organisms are commonly employed as biomonitors for environmental risk assessment.In this study,we aimed to investigate the spatial and temporal patterns of the macrobenthic community,which is influenced b...Macrobenthic organisms are commonly employed as biomonitors for environmental risk assessment.In this study,we aimed to investigate the spatial and temporal patterns of the macrobenthic community,which is influenced by environmental factors of sediments and bottom water layer.We sampled a total of 12,11,10,and 11 stations in the Shengsi Archipelago during June 2010,August 2010,November 2020,and April 2021 respectively.A total of 124 species of macrobenthos were identified,with polychaetes being the dominant group.The abundance,biomass,and diversity indices exhibited no significant temporal differences.Similarly,biodiversity did not exhibit a clear spatial gradient,likely due to the small study area and the absence of significant differences in key factors such as depth.However,the stations with the lowest biodiversity values consistently appeared in the southwest region,possibly due to the impact of human activities.Significant differences in the macrobenthic community were observed between all months except between June and August,and mollusk Endopleura lubrica and polychaete Sigambra hanaokai were important contributors to these differences according to the results of the Similarity Percentages analysis.Suspended particulate matter(SPM)was identified as the primary driving factors of macrobenthic variability.In summary,the community structure underwent temporal changes influenced by complex current patterns,while biodiversity remained relatively stable.This study contributes to our understanding of the key environmental factors affecting macrobenthic communities and biodiversity.It also provides valuable data support for the long-term monitoring of macrobenthos and the environment in the Shengsi Archipelago.展开更多
Finless porpoises(FPs)serve as flagship species and key ecological indicators for assessing environmental quality.However,FPs are challenging to survey due to their elusive behavior and lack of distinctive features.St...Finless porpoises(FPs)serve as flagship species and key ecological indicators for assessing environmental quality.However,FPs are challenging to survey due to their elusive behavior and lack of distinctive features.Stranding and sighting events offer essential information on species diversity,distribution patterns,and potential threats.In this study,records from 1986 to 2023 were analyzed to assess the temporal and spatial distribution patterns of FP strandings and sightings in the Qiantang River Estuary,China.Results show an increase in the number of recorded events over time.Seasonal variations were evident,with a peak in strandings and sightings occurring in late winter.The frequency of records was higher during spring and moderate tides compared to neap tides,particularly in hydrologically normal years.Rapidly receding tides and sediment accumulation appear to restrict the activity space of FPs,thereby increasing the frequency of these events.Localized conditions associated with stranding and sighting events were classified into four categories:bifurcation zones,confluence zones,separation zones,and deep channels adjacent to concave banks.Deep channels,which are optimal for shipping,also elevate the risk of FP strandings.These findings offer valuable insights for the development and design of conservation strategies tailored to the needs of FPs in estuarine environments.展开更多
Due to the lack of the three-dimensional structure of the Zhaoji Salt Basin,the salt mining enterprises have obvious clustering when choosing sites.Production capacity declines rapidly as mining deepens,and the enterp...Due to the lack of the three-dimensional structure of the Zhaoji Salt Basin,the salt mining enterprises have obvious clustering when choosing sites.Production capacity declines rapidly as mining deepens,and the enterprises are entering a stage of stagnation in production.In this study,a dense seismic array of 125 short-period stations was deployed around the core mining area and its vicinity of the salt mine industry,we used the ambient noise tomography(ANT)method to image the three-dimensional shear wave velocity structure at the depth shallower than 3 km.The results indicate:(1)The overall shear wave velocity in the study area is relatively lower,ranging from 0.8 to 1.8 km/s,which could be related to the loose and thick deposition of the Zhaoji sub-depression.(2)The three-dimensional shear wave velocity structure reveals that the sedimentary thickness of the Zhaoji sub-depression is deeper in the southeast and shallower in the northwest,with the sedimentary center located around Heping Town and Dahuangzhuang Town.(3)The Zhaoji salt mine is a low-velocity anomalous zone in the shear wave velocity structure with an inverse‘C'character spreading along Nanchenji Town and Zhaoji Town,with a depth ranging from approximately 1.2 to 2.8 km,it may be caused by the development of rock fissures due to water extraction and injection.The surrounding rock exhibits relatively high velocity,which reflects the morphological characteristics of the Zhaoji Salt Basin.The three-dimensional shear wave velocity model obtained in this study provides scientific guidance for the industrial exploitation of the Zhaoji salt mine and reference for salt exploration of the Hongze Salt Basin.It also provides an important basis for the seismic risk assessment of the salt basins.Simultaneously,it holds significant implications for exploring the application of ambient noise tomography method in spatial detection of salt mine belt.展开更多
Coal-measure gas is a primary target with significant potential for the exploration of unconventional hydrocarbon resources.However,the spatiotemporal distribution and combination patterns of multi-type coal-measure g...Coal-measure gas is a primary target with significant potential for the exploration of unconventional hydrocarbon resources.However,the spatiotemporal distribution and combination patterns of multi-type coal-measure gases are yet to be clarified,directly impeding the sweet spot evaluation and exploration deployment of coal-measure gas.This study discussed the characteristics and distribution patterns of coal-measure gases in the Daniudi gas field in northeastern Ordos Basin,China,with abundant drilling data.The results indicate that the coal seams variably thin upward and are mainly seen in the first and second members of the Taiyuan Formation(also referred to as the Tai 1 and Tai 2 members,respectively)and the first member of the Shanxi Formation(Shan 1 Member).Nos.8,5 and 3 coal seams are laterally continuous,and significantly thicker in its southern part compared to the northern part.Moreover,carbonaceous mudstones and shales are better developed in the southern part,where limestones are only observed in the Tai 1 Member.Based on the main lithological types,we identified three lithologic roofs of coal seams,that is,limestone,mudstone,and sandstone,which determine the spatiotemporal distribution of coal-measure gases.Besides bauxite gas in the Benxi Formation,the coal-measure gases include tight-sand gas,coalbed methane(CBM),coal-measure shale gas,and tight-limestone gas,with CBM typically associated with coal-measure shale gas.The combinations of different types of coal-measure gas vary across different layers and regions.Tight-sand gas is well-developed in areas where tight sandstones are in contact with coal-measures.From the Taiyuan to the Shanxi formations,CBM gradually transitions into a combination of CBM and coal-measure shale gas,and coal-measure shale gas.Nos.8 and 5 coal seams in low-lying areas exhibit favorable gas-bearing properties due to their large thickness and favorable roof lithologies,serving as prospective play fairways.Mudstone and limestone roofs are more conducive to achieving good gas-bearing properties.The direct contact between sandstones and coal seams tends to result in the formation of tight-sand gas and a reduced gas content of CBM.While focusing on single types of gas reservoirs such as CBM and tight-sand gas,it is essential to consider the concurrent exploration of various coal-measure gas combinations to discover more additional gas resources and guide exploration deployment.展开更多
High-resolution vehicular emissions inventories are important for managing vehicular pollution and improving urban air quality. This study developed a vehicular emission inventory with high spatio-temporal resolution ...High-resolution vehicular emissions inventories are important for managing vehicular pollution and improving urban air quality. This study developed a vehicular emission inventory with high spatio-temporal resolution in the main urban area of Chongqing, based on realtime traffic data from 820 RFID detectors covering 454 roads, and the differences in spatiotemporal emission characteristics between inner and outer districts were analysed. The result showed that the daily vehicular emission intensities of CO, hydrocarbons, PM2.5, PM10,and NO_(x) were 30.24, 3.83, 0.18, 0.20, and 8.65 kg/km per day, respectively, in the study area during 2018. The pollutants emission intensities in inner district were higher than those in outer district. Light passenger cars(LPCs) were the main contributors of all-day CO emissions in the inner and outer districts, from which the contributors of NO_(x) emissions were different. Diesel and natural gas buses were major contributors of daytime NO_(x) emissions in inner districts, accounting for 40.40%, but buses and heavy duty trucks(HDTs) were major contributors in outer districts. At nighttime, due to the lifting of truck restrictions and suspension of buses, HDTs become the main NO_(x) contributor in both inner and outer districts,and its three NO_(x) emission peak hours were found, which are different to the peak hours of total NO_(x) emission by all vehicles. Unlike most other cities, bridges and connecting channels are always emission hotspots due to long-time traffic congestion. This knowledge will help fully understand vehicular emissions characteristics and is useful for policymakers to design precise prevention and control measures.展开更多
For quantitatively explaining the correlations between the vascular plant species abundance (VPSA) and habitat factors, a spatial simulation method has been developed to simulate the distribution of VPSA on the Qingha...For quantitatively explaining the correlations between the vascular plant species abundance (VPSA) and habitat factors, a spatial simulation method has been developed to simulate the distribution of VPSA on the Qinghai-Tibet Plateau. In this paper, the vascular plant type, land cover, mean annual biotemperature, average total annual precipitation, topographic relief, patch connectivity and ecological diversity index were selected to screen the best correlation equation between the VPSA and habitat factors on the basis of 37 national nature reserves on the Qinghai-Tibet Plateau. The research results show that the coefficient of determination between VPSA and habitat factors is 0.94, and the mean error is 2.21 types per km<sup>2</sup>. The distribution of VPSA gradually decreases from southeast to northwest, and reduces with increasing altitude except the desert area of Qaidam Basin. Furthermore, the scenarios of VPSA on the Qinghai-Tibet Plateau during the periods from 1981 to 2010 (T0), from 2011 to 2040 (T2), from 2041 to 2070 (T3) and from 2071 to 2100 (T4) were simulated by combining the land cover change and the climatic scenarios of CMIP5 RCP2.6, RCP4.5 and RCP8.5. The simulated results show that the VPSA would generally decrease on the Qinghai-Tibet Plateau from T0 to T4. The VPSA has the largest change ratio under RCP8.5 scenario, and the smallest change ratio under RCP2.6 scenario. In general, the dynamic change of habitat factors would directly affect the spatial distribution of VPSA on the Qinghai- Tibet Plateau in the future.展开更多
Intense anthropogenic exploitation has altered distribution of forest resources. This change was analyzed using visual interpretation of satellite data of 1979, 1999 and 2009. Field and interactive social surveys were...Intense anthropogenic exploitation has altered distribution of forest resources. This change was analyzed using visual interpretation of satellite data of 1979, 1999 and 2009. Field and interactive social surveys were conducted to identify spatial trends in forest degradation and data were mapped on forest cover and land use maps. Perceptions of villagers were compiled in a pictorial representation to understand changes in forest resource distribution in central Himalaya from 1970 to 2010. For- ested areas were subject to degradation and isolation due to loss of con- necting forest stands. Species like Lantana camara and Eupatorium adenophorum invaded forest landscapes. Intensity of human pressure differed by forest type and elevation. An integrated approach is needed to monitor forest resource distribution and disturbance.展开更多
[Objective] The paper was to investigate the spatio-temporal distribution of fishery resources in the northern South China Sea and to provide reference for scientific evaluation and effective protection of fishery res...[Objective] The paper was to investigate the spatio-temporal distribution of fishery resources in the northern South China Sea and to provide reference for scientific evaluation and effective protection of fishery resources in the northern South China Sea. [Methods] Based on monitoring data and satellite remote sensing data [including Sea Surface Temperature(SST), Chlorophyll a concentration(Chl a) and Sea Surface Wind(SSW)] in winter(January to February) and summer(August to September) in the northern South China Sea, the relationship between spatio-temporal distribution of fishery resources and marine environment was investigated by using Generalized Linear Models(GLM), fishing ground gravity and correlation analysis. [Results] The suitable SST and Chl a of light falling-net fishing ground in winter were 17-23°C and 0.2-0.6 mg/m3, respectively. The suitable SST and Chl a in summer were approximately 28°C and 0.2-1.0 mg/m3. Standardized Catch Per Unit Effort(SCPUE) was higher in summer(2-4) and lower in winter(1-3). From winter to summer, the fishing ground gravity migrated to the east about 1 °E. [Conclusion] The spatio-temporal distribution of fishery resources is related to eastern Hainan-western Guangdong upwelling and the coastal flow, caused by the monsoon in the northern South China Sea, and the major catch species of light falling-net.展开更多
Based on the relevant statistics on the agricultural non-point source pollution in Binzhou City,we studied the spatio-temporal variation in agricultural non-point source nitrogen pollution and phosphorus pollution in ...Based on the relevant statistics on the agricultural non-point source pollution in Binzhou City,we studied the spatio-temporal variation in agricultural non-point source nitrogen pollution and phosphorus pollution in Binzhou City during 2008-2015. The results showed that the agricultural non-point source nitrogen pollution and phosphorus pollution in Binzhou City changed from 114400 t and 28800 t in 2008 to110600 t and 24400 t in 2015,respectively; for the non-point source nitrogen pollution sources,the proportion of chemical fertilizer,manure and domestic sewage changed from 80. 41%,10. 47% and 9. 13% in 2008 to 82. 94%,4. 77% and 12. 29% in 2015,respectively; for the non-point source phosphorus pollution sources,the proportion of chemical fertilizer,manure and domestic sewage changed from 89. 29%,8. 32% and 2. 39% in 2008 to 91. 6%,4. 78% and 3. 62% in 2015,respectively; in 2015,the non-point source nitrogen pollution was most serious in Wudi County and Huimin County and least serious in Zhanhua County; the non-point source phosphorus pollution was most serious in Zouping County and least serious in Wudi County.展开更多
Due to the importance of riparian zone in maintaining and protecting regional biodiversity, increasingly more ecologists paid their attentions to riparian zone and had been aware of the important effects of riparian z...Due to the importance of riparian zone in maintaining and protecting regional biodiversity, increasingly more ecologists paid their attentions to riparian zone and had been aware of the important effects of riparian zone in basic study and practical management. In this study, 42 sampling belts (10 m?00 m) parallel to the bank of Xiangxi River at different elevations in Shennongjia Area were selected to investigate the riparian vegetation and rare plants. 14 species of rare plants were found distributing in riparian zone, accounting for 42.4% of the total rare plant species in Shennongjia Area. The main distribution range of the 14 rare plant species was the evergreen and deciduous mixed broadleaved forest at elevation of 1200-1800 m, where, species diversity of plant community was the maximum at the moderate elevation. The analysis of TWINSPAN divided the 14 rare species into 3 groups against the elevation, namely low elevation species group, moderate elevation species group, and high elevation species group. The analysis of DCA ordination showed similar results to that of TWINSPAN. In the paper, the authors discussed the reasons forming the distribution pattern of rare plant species, and pointed out that the important function of riparian zone on rare plant species protection.展开更多
The relationships of 42 species of ground moss with six environmental factors in 41 sites on Changbai Mountain Biosphere Reserve were analyzed. Four site groups and four groups of ground moss ecological species were i...The relationships of 42 species of ground moss with six environmental factors in 41 sites on Changbai Mountain Biosphere Reserve were analyzed. Four site groups and four groups of ground moss ecological species were identified using the method of Two-way Indicator Species Analysis (TWINSPAN). The results of Detrended Canonical. Correspondence Analysis (DCCA) showed that altitude, soil sand content, soil acidity, forest canopy coverage and soil water content are the five major environmental factors influencing the distributional patterns of the moss species. The four groups of ecological species, which correspond well with the four site groups, are projected on the species-environment biplot of DCCA. Group 1 dominated in the bogs of Larix olgensis forest, group 2 in the alpine tundra, group 3 in the dense conifer forest, and group 4 mainly in the Betula ermanii community and the Betula ermanii-Larix olgensis forest in sub-alpine respectively.展开更多
[Objective] The aim of this study was to reveal and analyze the spatial distribution pattern of thrip（Odentot hrips lati） on alfalfa（Medicago sativa）.[Method] Within alfalfa plantation areas,experimental plots wit...[Objective] The aim of this study was to reveal and analyze the spatial distribution pattern of thrip（Odentot hrips lati） on alfalfa（Medicago sativa）.[Method] Within alfalfa plantation areas,experimental plots with the sizes of 10×10,10×20,10×30,20×30,20×40,20×80,30×30,30×40,30×50,40×40,40×50,40×80 and 50×50 m2 respectively were set up in the randomly selected sampling sites of 1 m ×2 m in size.During bud-emerging period and florescence period of alfalfa in the experimental plots,the number of thrips was counted and their distribution pattern was measured using XU Ru-mei＇s method.[Result] During bud-emerging period of alfalfa,the spatial distribution of thrips assumed an elliptic shape sized of 40×30-40×40 cm2 at horizontal level and that presented an ascending-falling trend of tress density down from the top at vertical level.During the florescence period of alfalfa,it showed a homogeneous distribution or randomly distributed pattern at horizontal level and a falling trend of tress density from the top to the apex to the root at vertical level.[Conclusion] Our results provide theoretical basis for field selection of insect-resistant alfalfa varieties.展开更多
文摘This study attempted to compare the performance of local polynomial interpolation,inverse distance weighted interpolation,and ordinary kriging in studying distribution patterns of swimming crabs.Cross-validation was used to select the optimum method to get distribution results,and kriging was used for making spatial variability analysis.Data were collected from 87 sampling stations in November of 2015(autumn)and February(winter),May(spring)and August(summer)of 2016.Results indicate that swimming crabs widely distributed in autumn and summer:in the summer,they were more spatially independent,and resources in each sampling station varied a lot;in the winter and spring,the abundance of crabs was much lower,but the individual crab size was bigger,and they showed the patchy and more concentrative distribution pattern,which means they were more spatially dependent.Distribution patterns were in accordance with ecological migration features of swimming crabs,which were affected by the changing marine environment.This study could infer that it is applicable to study crab fishery or even other crustacean species using geostatistical analysis.It not only helps practitioners have a better understanding of how swimming crabs migrate from season to season,but also assists researchers in carrying out a more comprehensive assessment of the fishery.Therefore,it may facilitate advancing the implementation in the pilot quota management program of swimming crabs in northern Zhejiang fishing grounds.
基金the Chinese Academy of Sciences Research Center for Ecology and Environment of Central Asia(RCEECA),the construction and joint research for the China-Tajikistan“Belt and Road”Joint Laboratory on Biodiversity Conservation and Sustainable Use(2024YFE0214200)the Shanghai Cooperation Organization Partnership and International Technology Cooperation Plan of Science and Technology Projects(2023E01018,2025E01056)the Chinese Academy of Sciences President’s International Fellowship Initiative(PIFI)(2024VBC0006).
文摘Tajikistan represents a core region of the biodiversity hotspot in Central Asian mountains and has exceptional vascular plant diversity.However,the species diversity of the country faces urgent conservation challenges.There has been a lack of a comprehensive and multidimensional assessment to inform strategic conservation planning.Therefore,this study integrated 4 key biodiversity indices including species richness(SR),phylogenetic diversity(PD),threatened species richness(TSR),and endemic species richness(ESR)to map species diversity distribution patterns,identify conservation gaps,and elucidate their effects of climatic factors.This study revealed that species diversity shows a clear trend of decreasing from the western region to the eastern region of Tajikistan.The central–western mountains(specifically the Gissar-Darvasian and Zeravshanian regions)emerge as irreplaceable biodiversity hotspots.However,we found a severe spatial mismatch between these priority areas and the existing protected areas(PAs).Protection coverage for all hotspots was alarmingly low,ranging from 31.00%to 38.00%.Consequently,a critical 64.80%of integrated priority areas fall outside of the current PAs,representing a major conservation gap.This study identified precipitation seasonality and isothermality as the principal drivers,collectively explaining over 50.00%of the diversity variation and suggesting high vulnerability to hydrological shifts.Furthermore,we detected significant geographic sampling bias in the public biodiversity databases,with the most critical hotspot being systematically under-sampled.This study provides a robust scientific basis for conservation action,highlighting the urgent need to strategically expand PAs in the under-protected southwestern region and to mitigate critical sampling gaps through targeted data digitization and field surveys.These measures are indispensable for securing Tajikistan’s unique biodiversity and achieving the Kunming-Montreal Global Biodiversity Framework Target 3(“30×30 Protection”).
基金This paper was supported by the National Natural Sci-ence Foundation of China (Grant No. 40371001) and the Youth Foundation of Beijing Normal University
文摘An improved Carnegie Ames Stanford Approach model （CASA model） was used to estimate the net primary productivity （NPP） of the Northeast China Transect （NECT） every month from 1982 to 2000. The spatial-temporal distribution of NPP along NECT and its response to climatic change were also analyzed. Results showed that the change tendency of NPP spatial distribution in NECT is quite similar to that of precipitation and their spatial correlation coefficient is up to 0.84 （P 〈 0.01）. The inter-annual variation of NPP in NECT is mainly affected by the change of the aestival NPP every year, which accounts for 67.6% of the inter-annual increase in NPP and their spatial correlation coefficient is 0.95 （P 〈 0.01）. The NPP in NECT is mainly cumulated between May and September, which accounts for 89.8% of the annual NPP. The NPP in summer （June to August） accounts for 65.9% of the annual NPP and is the lowest in winter. Recent climate changes have enhanced plant growth in NECT. The mean NPP increased 14.3% from 1980s to 1990s. The inter-annual linear trend of NPP is 4.6 gC·m^-2·a^-1, and the relative trend is 1.17%, which owns mainly to the increasing temperature.
文摘The cloud-to-ground lightning data between 2007 and 2008 were collected by lightning detection and location system,which was composed of four lightning detectors in four different sites of Dalian area.The spatio-temporal distribution of cloud-to-ground lightning in surrounding areas of Dalian was analyzed from several aspects of polarity distribution,diurnal variation,lightning intensity and lightning density.The results showed that the number of negative lightning accounted for 93.9% of the total number of lightning,and its average lightning intensity was 27.99 kA.The number of positive lightning accounted for 6.1% of the total number of lightning,and its average lightning intensity was 35.56 kA.The diurnal variation of lightning frequency showed an obvious structure of two peaks (17:00-18:00 and 04:00-05:00) and two valleys (09:00-10:00 and 00:00-01:00).The number of lightning between May and September was 91.5% of the annual number,and the lightning occurred the most frequently between June and August.Most of positive and negative lightning was at the intensity of 15-35 kA,80.0% lower than 40 kA,and 99.3% lower than 100 kA.The lightning density had obvious regional differences in distribution,high in the Liaodong Bay and the Dalian Bay and low in inland areas.Therefore,coastal areas should attract more attention in lightning disaster defense in the surrounding areas of Dalian.
基金supported by the National Science Foundation of China(32201643)the Key Research Projects of Yibin,research and integrated demonstration and key technologies for smart bamboo industry(YBZD2024-1).
文摘Climate change disrupts the distribution of species and restructures their richness patterns.The genus of Asian bamboo,Phyllostachys,possesses significant ecological and economic values,and represents the most speciesrich genus in the Bambusoideae subfamily.Based on the distribution data of 46 species and 20 environmental variables,we used the MaxEnt model combined with ArcGIS calculations to simulate current and future potential richness distributions under three distinct CO_(2) emission scenarios.The results showed that the MaxEnt model had a good predictive ability,with a mean area under the working characteristic curve(AUC value)of 0.91 for all species.The main environmental variables that impacted the future distribution of most Phyllostachys species were elevation,variations of seasonal precipitation,and mean diurnal range.Phyllostachys species are currently concentrated in southeastern China.Under future climate projections,18 species exhibited significant habitat contraction across three or more future climate scenarios,but suitable habitats for other species will expand.This enhancement is most pronounced under the extreme climate scenario(2090s-SSP585),primarily driven by high species gains contributing to elevated turnover values across scenarios.The center of maximum richness will progressively shift southwestward over time.Predictive modeling of Phyllostachys richness distribution dynamics under climate change enhances our understanding of its biogeography and informs strategic introduction programs to bamboo management and augments China’s carbon sequestration capacity.
基金supported by the National Natural Science Foundation of China(No.U21B2062).
文摘The isolated fracture-vug systems controlled by small-scale strike-slip faults within ultra-deep carbonate rocks of the Tarim Basin exhibit significant exploration potential.The study employs a novel training set incorporating innovative fault labels to train a U-Net-structured CNN model,enabling effective identification of small-scale strike-slip faults through seismic data interpretation.Based on the CNN faults,we analyze the distribution patterns of small-scale strike-slip faults.The small-scale strike-slip faults can be categorized into NNW-trending and NE-trending groups with strike lengths ranging 200–5000 m.The development intensity of small-scale strike-slip faults in the Lower Yingshan Member notably exceeds that in the Upper Member.The Lower and Upper Yingshan members are two distinct mechanical layers with contrasting brittleness characteristics,separated by a low-brittleness layer.The superior brittleness of the Lower Yingshan Member enhances the development intensity of small-scale strike-slip faults compared to the upper member,while the low-brittleness layer exerts restrictive effects on vertical fault propagation.Fracture-vug systems formed by interactions of two or more small-scale strike-slip faults demonstrate larger sizes than those controlled by individual faults.All fracture-vug system sizes show positive correlations with the vertical extents of associated small-scale strike-slip faults,particularly intersection and approaching fracture-vug systems exhibit accelerated size increases proportional to the vertical extents.
基金National Natural Science Foundation of China,No.41421001,No.41590845,No.41571388National Key Basic Research Program,No.2015CB954101
文摘Landforms are an important factor determining the spatial pattern of cropland through allocation of surface water and heat. Therefore, it is of great importance to study the change in cropland distribution from the perspective of geomorphologic divisions. Based on China's multi-year land cover data(1990, 1995, 2000, 2005, 2010 and 2015) and geomorphologic regionalization data, we analyzed the change in cropland area and its distribution pattern in six geomorphologic regions of China over the period of 1990-2015 with the aid of GIS techniques. Our results showed that the total cropland area increased from 177.1 to 178.5 million ha with an average increase rate of 0.03%. Cropland area decreased in southern China and increased in northern China. Region I(Eastern hilly plains) had the highest cropland increase rate, while the cropland dynamic degree of Region IV(Northwestern middle and high mountains, basins and plateaus) was significantly higher than that of other regions. The barycenter of China's cropland shifted from northern China to the northwest over the 25-year period. Regions IV and I were the two regions with the greatest increase of cropland. Region II(Southeastern low and middle mountains) and Region V(Southwestern middle and low mountains, plateaus and basins) were the main decreasing cropland regions. The area of cropland remained almost unchanged in Region III(Northern China and Inner Mongolia eastern-central mountains and plateaus) and Region VI(Tibetan Plateau). The loss of cropland occurred mostly in Regions I and II as a result of growing industrialization and urbanization, while the increase of cropland occurred mainly in Region IV because of reclamation of grassland and other wasteland. These analyzing results would provide fundamental information for further studies of urban planning, ecosystem management, and natural resourcesconservation in China.
基金The Scientific Research Fund of the Second Institute of Oceanography,Ministry of Natural Resources,China under contract Nos SZ2302 and JG2209.
文摘Macrobenthic organisms are commonly employed as biomonitors for environmental risk assessment.In this study,we aimed to investigate the spatial and temporal patterns of the macrobenthic community,which is influenced by environmental factors of sediments and bottom water layer.We sampled a total of 12,11,10,and 11 stations in the Shengsi Archipelago during June 2010,August 2010,November 2020,and April 2021 respectively.A total of 124 species of macrobenthos were identified,with polychaetes being the dominant group.The abundance,biomass,and diversity indices exhibited no significant temporal differences.Similarly,biodiversity did not exhibit a clear spatial gradient,likely due to the small study area and the absence of significant differences in key factors such as depth.However,the stations with the lowest biodiversity values consistently appeared in the southwest region,possibly due to the impact of human activities.Significant differences in the macrobenthic community were observed between all months except between June and August,and mollusk Endopleura lubrica and polychaete Sigambra hanaokai were important contributors to these differences according to the results of the Similarity Percentages analysis.Suspended particulate matter(SPM)was identified as the primary driving factors of macrobenthic variability.In summary,the community structure underwent temporal changes influenced by complex current patterns,while biodiversity remained relatively stable.This study contributes to our understanding of the key environmental factors affecting macrobenthic communities and biodiversity.It also provides valuable data support for the long-term monitoring of macrobenthos and the environment in the Shengsi Archipelago.
基金The National Natural Science Foundation of China under contract Nos 42176214 and 42176170the Zhejiang Provincial Natural Science Foundation of China under contract Nos LZJWZ22E090002 and LZJWY22E090006the Key Program of the President of the Zhejiang Institute of Hydraulics and Estuaries under contract No.ZIHE21Z001.
文摘Finless porpoises(FPs)serve as flagship species and key ecological indicators for assessing environmental quality.However,FPs are challenging to survey due to their elusive behavior and lack of distinctive features.Stranding and sighting events offer essential information on species diversity,distribution patterns,and potential threats.In this study,records from 1986 to 2023 were analyzed to assess the temporal and spatial distribution patterns of FP strandings and sightings in the Qiantang River Estuary,China.Results show an increase in the number of recorded events over time.Seasonal variations were evident,with a peak in strandings and sightings occurring in late winter.The frequency of records was higher during spring and moderate tides compared to neap tides,particularly in hydrologically normal years.Rapidly receding tides and sediment accumulation appear to restrict the activity space of FPs,thereby increasing the frequency of these events.Localized conditions associated with stranding and sighting events were classified into four categories:bifurcation zones,confluence zones,separation zones,and deep channels adjacent to concave banks.Deep channels,which are optimal for shipping,also elevate the risk of FP strandings.These findings offer valuable insights for the development and design of conservation strategies tailored to the needs of FPs in estuarine environments.
基金supported by the National Key R&D Program of China(No.2024YFC3012902)the National Natural Science Foundation of China(No.42074070)supported by the Huai’an Earthquake Prevention and Disaster Reduction Service Center“Salt Cavern Exploration Project”(No.HAZC-2021050155-001)。
文摘Due to the lack of the three-dimensional structure of the Zhaoji Salt Basin,the salt mining enterprises have obvious clustering when choosing sites.Production capacity declines rapidly as mining deepens,and the enterprises are entering a stage of stagnation in production.In this study,a dense seismic array of 125 short-period stations was deployed around the core mining area and its vicinity of the salt mine industry,we used the ambient noise tomography(ANT)method to image the three-dimensional shear wave velocity structure at the depth shallower than 3 km.The results indicate:(1)The overall shear wave velocity in the study area is relatively lower,ranging from 0.8 to 1.8 km/s,which could be related to the loose and thick deposition of the Zhaoji sub-depression.(2)The three-dimensional shear wave velocity structure reveals that the sedimentary thickness of the Zhaoji sub-depression is deeper in the southeast and shallower in the northwest,with the sedimentary center located around Heping Town and Dahuangzhuang Town.(3)The Zhaoji salt mine is a low-velocity anomalous zone in the shear wave velocity structure with an inverse‘C'character spreading along Nanchenji Town and Zhaoji Town,with a depth ranging from approximately 1.2 to 2.8 km,it may be caused by the development of rock fissures due to water extraction and injection.The surrounding rock exhibits relatively high velocity,which reflects the morphological characteristics of the Zhaoji Salt Basin.The three-dimensional shear wave velocity model obtained in this study provides scientific guidance for the industrial exploitation of the Zhaoji salt mine and reference for salt exploration of the Hongze Salt Basin.It also provides an important basis for the seismic risk assessment of the salt basins.Simultaneously,it holds significant implications for exploring the application of ambient noise tomography method in spatial detection of salt mine belt.
基金funded by SINOPEC Science and Technology Research Program(No.P23206No.P23230).
文摘Coal-measure gas is a primary target with significant potential for the exploration of unconventional hydrocarbon resources.However,the spatiotemporal distribution and combination patterns of multi-type coal-measure gases are yet to be clarified,directly impeding the sweet spot evaluation and exploration deployment of coal-measure gas.This study discussed the characteristics and distribution patterns of coal-measure gases in the Daniudi gas field in northeastern Ordos Basin,China,with abundant drilling data.The results indicate that the coal seams variably thin upward and are mainly seen in the first and second members of the Taiyuan Formation(also referred to as the Tai 1 and Tai 2 members,respectively)and the first member of the Shanxi Formation(Shan 1 Member).Nos.8,5 and 3 coal seams are laterally continuous,and significantly thicker in its southern part compared to the northern part.Moreover,carbonaceous mudstones and shales are better developed in the southern part,where limestones are only observed in the Tai 1 Member.Based on the main lithological types,we identified three lithologic roofs of coal seams,that is,limestone,mudstone,and sandstone,which determine the spatiotemporal distribution of coal-measure gases.Besides bauxite gas in the Benxi Formation,the coal-measure gases include tight-sand gas,coalbed methane(CBM),coal-measure shale gas,and tight-limestone gas,with CBM typically associated with coal-measure shale gas.The combinations of different types of coal-measure gas vary across different layers and regions.Tight-sand gas is well-developed in areas where tight sandstones are in contact with coal-measures.From the Taiyuan to the Shanxi formations,CBM gradually transitions into a combination of CBM and coal-measure shale gas,and coal-measure shale gas.Nos.8 and 5 coal seams in low-lying areas exhibit favorable gas-bearing properties due to their large thickness and favorable roof lithologies,serving as prospective play fairways.Mudstone and limestone roofs are more conducive to achieving good gas-bearing properties.The direct contact between sandstones and coal seams tends to result in the formation of tight-sand gas and a reduced gas content of CBM.While focusing on single types of gas reservoirs such as CBM and tight-sand gas,it is essential to consider the concurrent exploration of various coal-measure gas combinations to discover more additional gas resources and guide exploration deployment.
基金supported by the National Key Research Program(No.2018YFB1601105,No.2018YFB1601102)the Natural Science Foundation of China(No.41975165,No.U1811463)Chongqing Science and Technology Project(No.cstc2019jscxfxydX0035)。
文摘High-resolution vehicular emissions inventories are important for managing vehicular pollution and improving urban air quality. This study developed a vehicular emission inventory with high spatio-temporal resolution in the main urban area of Chongqing, based on realtime traffic data from 820 RFID detectors covering 454 roads, and the differences in spatiotemporal emission characteristics between inner and outer districts were analysed. The result showed that the daily vehicular emission intensities of CO, hydrocarbons, PM2.5, PM10,and NO_(x) were 30.24, 3.83, 0.18, 0.20, and 8.65 kg/km per day, respectively, in the study area during 2018. The pollutants emission intensities in inner district were higher than those in outer district. Light passenger cars(LPCs) were the main contributors of all-day CO emissions in the inner and outer districts, from which the contributors of NO_(x) emissions were different. Diesel and natural gas buses were major contributors of daytime NO_(x) emissions in inner districts, accounting for 40.40%, but buses and heavy duty trucks(HDTs) were major contributors in outer districts. At nighttime, due to the lifting of truck restrictions and suspension of buses, HDTs become the main NO_(x) contributor in both inner and outer districts,and its three NO_(x) emission peak hours were found, which are different to the peak hours of total NO_(x) emission by all vehicles. Unlike most other cities, bridges and connecting channels are always emission hotspots due to long-time traffic congestion. This knowledge will help fully understand vehicular emissions characteristics and is useful for policymakers to design precise prevention and control measures.
基金National Key R&D Program of China,No.2017YFA0603702,No.2018YFC0507200National Natural Science Foundation of China,No.41271406,No.91325204Innovation Project of LREIS(O88RA600YA)
文摘For quantitatively explaining the correlations between the vascular plant species abundance (VPSA) and habitat factors, a spatial simulation method has been developed to simulate the distribution of VPSA on the Qinghai-Tibet Plateau. In this paper, the vascular plant type, land cover, mean annual biotemperature, average total annual precipitation, topographic relief, patch connectivity and ecological diversity index were selected to screen the best correlation equation between the VPSA and habitat factors on the basis of 37 national nature reserves on the Qinghai-Tibet Plateau. The research results show that the coefficient of determination between VPSA and habitat factors is 0.94, and the mean error is 2.21 types per km<sup>2</sup>. The distribution of VPSA gradually decreases from southeast to northwest, and reduces with increasing altitude except the desert area of Qaidam Basin. Furthermore, the scenarios of VPSA on the Qinghai-Tibet Plateau during the periods from 1981 to 2010 (T0), from 2011 to 2040 (T2), from 2041 to 2070 (T3) and from 2071 to 2100 (T4) were simulated by combining the land cover change and the climatic scenarios of CMIP5 RCP2.6, RCP4.5 and RCP8.5. The simulated results show that the VPSA would generally decrease on the Qinghai-Tibet Plateau from T0 to T4. The VPSA has the largest change ratio under RCP8.5 scenario, and the smallest change ratio under RCP2.6 scenario. In general, the dynamic change of habitat factors would directly affect the spatial distribution of VPSA on the Qinghai- Tibet Plateau in the future.
文摘Intense anthropogenic exploitation has altered distribution of forest resources. This change was analyzed using visual interpretation of satellite data of 1979, 1999 and 2009. Field and interactive social surveys were conducted to identify spatial trends in forest degradation and data were mapped on forest cover and land use maps. Perceptions of villagers were compiled in a pictorial representation to understand changes in forest resource distribution in central Himalaya from 1970 to 2010. For- ested areas were subject to degradation and isolation due to loss of con- necting forest stands. Species like Lantana camara and Eupatorium adenophorum invaded forest landscapes. Intensity of human pressure differed by forest type and elevation. An integrated approach is needed to monitor forest resource distribution and disturbance.
基金Supported by Central Public-interest Scientific Institution Basal Research Fund,CAFS(2018HY-ZD0104)National Key R&D Program of China(2018YFD0900901)+1 种基金Natural Science Foundation of Guangdong Province,China(2018A030313120)State Key Laboratory of Tropical Oceanography,South China Sea Institute of Oceanology,Chinese Academy of Sciences(LTO1806)
文摘[Objective] The paper was to investigate the spatio-temporal distribution of fishery resources in the northern South China Sea and to provide reference for scientific evaluation and effective protection of fishery resources in the northern South China Sea. [Methods] Based on monitoring data and satellite remote sensing data [including Sea Surface Temperature(SST), Chlorophyll a concentration(Chl a) and Sea Surface Wind(SSW)] in winter(January to February) and summer(August to September) in the northern South China Sea, the relationship between spatio-temporal distribution of fishery resources and marine environment was investigated by using Generalized Linear Models(GLM), fishing ground gravity and correlation analysis. [Results] The suitable SST and Chl a of light falling-net fishing ground in winter were 17-23°C and 0.2-0.6 mg/m3, respectively. The suitable SST and Chl a in summer were approximately 28°C and 0.2-1.0 mg/m3. Standardized Catch Per Unit Effort(SCPUE) was higher in summer(2-4) and lower in winter(1-3). From winter to summer, the fishing ground gravity migrated to the east about 1 °E. [Conclusion] The spatio-temporal distribution of fishery resources is related to eastern Hainan-western Guangdong upwelling and the coastal flow, caused by the monsoon in the northern South China Sea, and the major catch species of light falling-net.
基金Supported by National College Students’Innovation and Entrepreneurship Training Program(201610449062)Research Fund Project of Binzhou University(BZXYG1308)
文摘Based on the relevant statistics on the agricultural non-point source pollution in Binzhou City,we studied the spatio-temporal variation in agricultural non-point source nitrogen pollution and phosphorus pollution in Binzhou City during 2008-2015. The results showed that the agricultural non-point source nitrogen pollution and phosphorus pollution in Binzhou City changed from 114400 t and 28800 t in 2008 to110600 t and 24400 t in 2015,respectively; for the non-point source nitrogen pollution sources,the proportion of chemical fertilizer,manure and domestic sewage changed from 80. 41%,10. 47% and 9. 13% in 2008 to 82. 94%,4. 77% and 12. 29% in 2015,respectively; for the non-point source phosphorus pollution sources,the proportion of chemical fertilizer,manure and domestic sewage changed from 89. 29%,8. 32% and 2. 39% in 2008 to 91. 6%,4. 78% and 3. 62% in 2015,respectively; in 2015,the non-point source nitrogen pollution was most serious in Wudi County and Huimin County and least serious in Zhanhua County; the non-point source phosphorus pollution was most serious in Zouping County and least serious in Wudi County.
基金This project was supported by National Natural Science Foundation of China (NSFC39970123) Changbai Mountain Open Research Station, Chinese Acedamy of Science.
文摘Due to the importance of riparian zone in maintaining and protecting regional biodiversity, increasingly more ecologists paid their attentions to riparian zone and had been aware of the important effects of riparian zone in basic study and practical management. In this study, 42 sampling belts (10 m?00 m) parallel to the bank of Xiangxi River at different elevations in Shennongjia Area were selected to investigate the riparian vegetation and rare plants. 14 species of rare plants were found distributing in riparian zone, accounting for 42.4% of the total rare plant species in Shennongjia Area. The main distribution range of the 14 rare plant species was the evergreen and deciduous mixed broadleaved forest at elevation of 1200-1800 m, where, species diversity of plant community was the maximum at the moderate elevation. The analysis of TWINSPAN divided the 14 rare species into 3 groups against the elevation, namely low elevation species group, moderate elevation species group, and high elevation species group. The analysis of DCA ordination showed similar results to that of TWINSPAN. In the paper, the authors discussed the reasons forming the distribution pattern of rare plant species, and pointed out that the important function of riparian zone on rare plant species protection.
文摘The relationships of 42 species of ground moss with six environmental factors in 41 sites on Changbai Mountain Biosphere Reserve were analyzed. Four site groups and four groups of ground moss ecological species were identified using the method of Two-way Indicator Species Analysis (TWINSPAN). The results of Detrended Canonical. Correspondence Analysis (DCCA) showed that altitude, soil sand content, soil acidity, forest canopy coverage and soil water content are the five major environmental factors influencing the distributional patterns of the moss species. The four groups of ecological species, which correspond well with the four site groups, are projected on the species-environment biplot of DCCA. Group 1 dominated in the bogs of Larix olgensis forest, group 2 in the alpine tundra, group 3 in the dense conifer forest, and group 4 mainly in the Betula ermanii community and the Betula ermanii-Larix olgensis forest in sub-alpine respectively.
基金Supported by Natural Science Foundation of Guizhou Province(J[2010]2248)~~
文摘[Objective] The aim of this study was to reveal and analyze the spatial distribution pattern of thrip（Odentot hrips lati） on alfalfa（Medicago sativa）.[Method] Within alfalfa plantation areas,experimental plots with the sizes of 10×10,10×20,10×30,20×30,20×40,20×80,30×30,30×40,30×50,40×40,40×50,40×80 and 50×50 m2 respectively were set up in the randomly selected sampling sites of 1 m ×2 m in size.During bud-emerging period and florescence period of alfalfa in the experimental plots,the number of thrips was counted and their distribution pattern was measured using XU Ru-mei＇s method.[Result] During bud-emerging period of alfalfa,the spatial distribution of thrips assumed an elliptic shape sized of 40×30-40×40 cm2 at horizontal level and that presented an ascending-falling trend of tress density down from the top at vertical level.During the florescence period of alfalfa,it showed a homogeneous distribution or randomly distributed pattern at horizontal level and a falling trend of tress density from the top to the apex to the root at vertical level.[Conclusion] Our results provide theoretical basis for field selection of insect-resistant alfalfa varieties.
