A new species, Triphleba conchiformis sp. nov., is described and illustrated. The species differs from other species of the genus by the characters of missing vein R2+3 and shell-like surstylus. The type specimens ar...A new species, Triphleba conchiformis sp. nov., is described and illustrated. The species differs from other species of the genus by the characters of missing vein R2+3 and shell-like surstylus. The type specimens are deposited in the Liaoning Key Laboratory of Urban Integrated Pest Management and Ecological Security, Shenyang University.展开更多
Steller chamaejasme L. (S. chamaejasme for short) is one of the most noxious unpalatable weeds in China, which has been frequently reported its negative interaction (i.e. competition and allelopathy) with other he...Steller chamaejasme L. (S. chamaejasme for short) is one of the most noxious unpalatable weeds in China, which has been frequently reported its negative interaction (i.e. competition and allelopathy) with other herbaceous species in grasslands. This study compared species diversity, biomass and sexual reproduction of herbaceous plants in meadows with S. chamaejasme and in open meadows without S. ehamaejasme in overgrazing meadows on the Tibetan Plateau in China to determine whether positive facilitation exist between S. chamaejasme and other herbaceous species under livestock's overgrazing. The results showed that there are more herbaceous species in meadows with S. chamaejasme than those in open meadows (35s and30s, respectively). Diversity index and above-ground biomass were also significantly higher in meadows with S. charnaejasme. There were 39% (11/28) of all species with sexual reproduction found in meadows with S. charnaejasme, which was 7 times more than those in open meadows. Our study showed that S. charnaejasme could provide biotic refuge for neighboring plants and preserve plant diversity from livestock's overgrazing in alpine meadows on the Tibetan Plateau. It also suggested that inter-specific facilitation between S. charnaejasme and other herbaceous species may play a key role in overgrazing alpine meadows.展开更多
Accurate wetland delineation is the basis of wetland definition and mapping, and is of great importance for wetland management and research. The Zoige Plateau on the Qinghai-Tibet Plateau was used as a research site f...Accurate wetland delineation is the basis of wetland definition and mapping, and is of great importance for wetland management and research. The Zoige Plateau on the Qinghai-Tibet Plateau was used as a research site for research on alpine wetland delineation. Several studies have analyzed the spatiotemporal pattern and dynamics of these alpine wetlands, but none have addressed the issues of wetland boundaries. The objective of this work was to discriminate the upper boundaries of alpine wetlands by coupling ecological methods and satellite observations. The combination of Landsat 8 images and supervised classification was an effective method for rapid identification of alpine wetlands in the Zoig6 Plateau. Wet meadow was relatively stable compared with hydric soils and wetland hydrology and could be used as a primary indicator for discriminating the upper boundaries of alpine wetlands. A slope of less than 4.5° could be used as the threshold value for wetland delineation. The normalized difference vegetation index (NDVI) in 434 field sites showed that a threshold value of 0.3 could distinguish grasslands from emergent marsh and wet meadow in September. The median normalized difference water index (NDWI) of emergent marsh remained more stable than that of wet meadow and grasslands during the period from September until July of the following year. The index of mean density in wet meadow zones was higher than the emergent and upland zones. Over twice the number of species occurred in the wet meadow zone compared with the emergent zone, and close to the value of upland zone. Alpine wetlands in the three reserves in 2014 covered 1175.19 kin2 with a classification accuracy of 75.6%. The combination of ecological methods and remote sensing technology will play an important role in wetland delineation at medium and small scales. The correct differentiation between wet meadow and grasslands is the key to improving the accuracy of future wetland delineation.展开更多
Remote sensing data from the Terra Moderate-Resolution Imaging Spectroradiometer (MODIS) and geospatial data were used to estimate grass yield and livestock carrying capacity in the Tibetan Autonomous Prefecture of Go...Remote sensing data from the Terra Moderate-Resolution Imaging Spectroradiometer (MODIS) and geospatial data were used to estimate grass yield and livestock carrying capacity in the Tibetan Autonomous Prefecture of Golog, Qing-hai, China. The MODIS-derived normalized difference vegetation index (MODIS-NDVI) data were correlated with the aboveground green biomass (AGGB) data from the aboveground harvest method. Regional regression model between the MODIS-NDVI and the common logarithm (LOG10) of the AGGB was significant (r2 = 0.51, P < 0.001), it was, there-fore, used to calculate the maximum carrying capacity in sheep-unit year per hectare. The maximum livestock carrying capacity was then adjusted to the theoretical livestock carrying capacity by the reduction factors (slope, distance to water, and soil erosion). Results indicated that the grassland conditions became worse, with lower aboveground palatable grass yield, plant height, and cover compared with the results obtained in 1981. At the same time, although the actual livestock numbers decreased, they still exceeded the proper theoretical livestock carrying capacity, and overgrazing rates ranged from 27.27% in Darlag County to 293.99% in Baima County. Integrating remote sensing and geographical information system technologies, the spatial and temporal conditions of the alpine grassland, trend, and projected stocking rates could be forecasted for decision making.展开更多
This paper demonstrates regional characteristics, a long-term decreasing trend, and decadal variations in the frequency of cold surge events based on daily mean temperature and daily minimum temperature data in China&...This paper demonstrates regional characteristics, a long-term decreasing trend, and decadal variations in the frequency of cold surge events based on daily mean temperature and daily minimum temperature data in China's Mainland from 1960 to 2008. During these 48 years four high frequency centers of cold surge events were located in Xinjiang, central North China, northeast China, and southeast China. A main frequency peak of cold surge events occurs in autumn for the four regions and another peak is detected in spring over northeast China and southeast China. The regional pattern of cold surge frequencies is in accordance with the perturbation kinetic energy distribution in October December, January, and February April. The long-term decreasing trend ( 0.2 times/decade) of cold surge frequencies in northeast China and decadal variations in China are related to the variations of the temperature difference between southern and northern China in the winter monsoon season; these variations are due to the significant rising of winter temperatures in high latitudes.展开更多
Ombrotrophic bogs are faithful archive of atmospheric metal deposition, but the potential for fens to reconstruct environmental change is often underestimated. In this study, some new data on the Pb depositional histo...Ombrotrophic bogs are faithful archive of atmospheric metal deposition, but the potential for fens to reconstruct environmental change is often underestimated. In this study, some new data on the Pb depositional history in northeast China were provided using two ^210Pb-dated peat sequences from a poor fen in the Fenghuang Mountain of Heilongjiang province. Anthropogenic, detritic and atmospheric soil sources were discriminated using a two-step sequential digestion (weak acid leaching to liberate mobile Pb which is often regarded as anthropogenic Pb, especially for recent samples) and a ratio of unsupported ^210Pb and supported ^210Pb with the logic of that the ^214Pb mainly represents the residual detritus (constant throughout the core) and the unsupported ^210Pb arises from atmospheric fallout. A higher ^210Pb/^214Pb suggests more contributions from atmospheric deposition to the Pb content in the peat, and a ratio of 10 was defined to indicate the boundary between detrific input and atmospheric deposition. The detritic Pb was estimated to be 10-13 mg·kg^-1, the anthropogenic Pb ranged from 10-80 mg·kg^-1, and the atmospheric soil-derived Pb ranged from 〈 5 mg·kg^-1 to 30 mg·kg^-1. The history of anthropogenic Pb pollution over the last 150 years was reconstructed, and the calculated Pb deposition rate (AR Pb) ranged from 5 to 56 mg·m^-2·yr^-1. Using Ti as a reliable reference, the enrichment factor of Pb (EF Pb) relative to the upper continental crust was calculated. Both AR Pb and EF Pb increased with time, especially after the foundation of the People's Republic of China. This is consistent with increasing industrialization and coal burning in the last 60 years in northeast China. The present record of anthropogenic Pb deposition was consistent with the previous reports and an increasing trend of environmental pollution due to anthropogenic activities, in contrasts to Europe and North America which have experienced a major environmental cleanup. For the first time, this work estimates atmospheric Pb deposition via a minerotrophic peat core in China. This will enhance the use of peat archives for studies of environmental change.展开更多
The paper analyzes the characteristics of rice production in Heilongjiang Reclamation Area(HRA)and the achievements made through innovative research and practice,evaluates the standardized mode of rice cultivation and...The paper analyzes the characteristics of rice production in Heilongjiang Reclamation Area(HRA)and the achievements made through innovative research and practice,evaluates the standardized mode of rice cultivation and technical standards for rice production,which play a key role in guaranteeing the growth of grain total output in Heilongjiang reclamation area and make great contributions to the national grain safety.展开更多
It is helpful to improve the seismic design theory of long-span continuous bridges for studying the seismic performance of each cantilever construction state.Taking the Bridge 1 in the north of Changbai-Mountain inter...It is helpful to improve the seismic design theory of long-span continuous bridges for studying the seismic performance of each cantilever construction state.Taking the Bridge 1 in the north of Changbai-Mountain international tourism resort as an example,the authors studied it in shutdown phase and the cantilever construction process,established the simulation model by using Midas / civil,and analyzed time-history of each construction stage for the bridge.The study shows that long-span bridge cantilever construction in northeastern China can be divided into two-year tasks for construction(suspending in winter).It is needed to think about seismic stability of the cantilever position in shut-down phase of winter.The effect of longitudinal vibration is the most disadvantageous influence to bridge,and its calculation results can provide reference for seismic design of similar bridges in the future.展开更多
Alpine-cold regions are characterized as hypoxia,strong wind,heavy rain,cold climate,huge temperature difference between day and night,and vertical climate. All these make it difficult for an emergency rescue when a n...Alpine-cold regions are characterized as hypoxia,strong wind,heavy rain,cold climate,huge temperature difference between day and night,and vertical climate. All these make it difficult for an emergency rescue when a natural disaster such as earthquake happens. Based on the characteristics of emergency rescue in alpinecold region,several multifunctional protective equipments have been developed by the Quartermaster Equipment Institute of General Logistics Departmen(tGLD)of the Chinese People's Liberation Army(CPLA). These equipments are lightweight,durable and environment adaptable.展开更多
Low winter temperature is generally recognized as the chief factor limiting the northward distribution of Osmanthus fragrans. O. fragrans has been cultivated in Kaifeng for nearly two decades, yet little is known rega...Low winter temperature is generally recognized as the chief factor limiting the northward distribution of Osmanthus fragrans. O. fragrans has been cultivated in Kaifeng for nearly two decades, yet little is known regarding how well this plant has adapted to the city's cold winter. In a city-wide survey, we periodically examined O. fragrans leaves for visible symptoms of freeze damage, then measured leaf soluble sugar content, leaf electric conductivity, palisade layer thickness/leaf thickness ratio, and spongy layer thickness/leaf thickness ratio of several cultivars. The data thus collected were assessed to determine the cultivars' cold resistance levels. Our results indicate that the northward distribution of O. fragrans may be limited primarily by low spring temperatures rather than low winter temperatures. O. fragrans Sijigui and Huangchuan Jingui are the most cold resistant O. fragrans cultivars in Kaifeng, China.展开更多
Grazing exclusion is widely adopted in restoring degraded alpine grasslands on the Qinghai-Tibetan Plateau. However, its effectiveness remains poorly understood. In this study, we investigated the effects of grazing e...Grazing exclusion is widely adopted in restoring degraded alpine grasslands on the Qinghai-Tibetan Plateau. However, its effectiveness remains poorly understood. In this study, we investigated the effects of grazing exclusion on plant productivity, species diversity and soil organic carbon (SOC) and soil total nitrogen (STN) storage along a transect spanning from east to west of alpine meadows in northern Tibet, China. After six years of grazing exclusion, plant cover, aboveground biomass (AGB), belowground biomass (BGB), SOC and STN were increased, but species diversity indices declined. The enhancement of AGB and SOC caused by grazing exclusion was correlated positively with mean annual precipitation (MAP). Grazing exclusion led to remarkable biomass increase of sedge species, especially Kobresia pygmaea, whereas decrease of biomass in forbs and no obvious change in grass, leguminous and noxious species. Root biomass was concentrated in the near surface layer (10 cm) after grazing exclusion. The effects of grazing exclusion on SOC storage were confined to shallow soil layer in sites with lower MAP. It is indicated that grazing exclusion is an effective measure to increase forage production and enhance soil carbon sequestration in the studied region. The effect is more efficient in sites with higher precipitation. However, the results revealed a tradeoff between vegetation restoration and ecological biodiversity. Therefore, carbon pools recover more quickly than plant biodiversity in the alpine meadows. We suggest that grazing exclusion should be combined with other measures to reconcile grassland restoration and biodiversitv conservation.展开更多
High performance concrete originated in the generation of high strength concrete, and it is a new high technology of concrete, is in common with high quality and in concrete. High durability on the perspective of impr...High performance concrete originated in the generation of high strength concrete, and it is a new high technology of concrete, is in common with high quality and in concrete. High durability on the perspective of improvement and become, use a lot of high quality raw materials and modern technology, is the main development direction of concrete. Because its comprehensive performance by the superiority of the focus of the society, the strict construction technology in the extensive application in the highway bridge, high performance can the use of concrete can improve the efficiency of its safety and avoid unnecessary accidents展开更多
Oil and gas breakthroughs have been achieved in the Zhongshen 1(ZS1) and 1 C(ZS1 C) wells in Cambrian pre-salt from the Tarim Basin in northwest China. However, Middle and Lower Cambrian reservoirs reveal substantial ...Oil and gas breakthroughs have been achieved in the Zhongshen 1(ZS1) and 1 C(ZS1 C) wells in Cambrian pre-salt from the Tarim Basin in northwest China. However, Middle and Lower Cambrian reservoirs reveal substantial differences in the geochemistry and secondary alteration characteristics between the oils collected from the two wells. High concentrations of thiadiamondoids and diamondoidthiols, including thiatetramantanes, tetramantanethiols, thiapentamantanes, and pentamantanethiols, are detected in the organic sulfur compound fraction of concentrated oil collected from the ZS1 C well, which samples the Lower Cambrian Xiaoerbulake Formation. Higher diamondoids, such as tetramantanes, pentamantanes, hexamantanes, and cyclohexamantane, also occur in the saturate fractions of the concentrated ZS1 C oil. The presence of these compounds is verified by mass spectra analysis and comparison with previous studies. During thermochemical sulfate reduction(TSR), the cage of higher diamondoids is interpreted to open because of sulfur radicals forming open-cage higher diamondoid-like thiols, followed by cyclization that leads to the formation of high thiadiamondoids. Using D_(16)-adamantane as an internal standard, the concentrations of lower diamondoids and thiadiamondoids of non-concentrated Cambrian oil from well ZS1 C are 83874 and8578 μg/g, respectively, which are far higher than Cambrian oil from well ZS1 and most Ordovician oils in the Tarim Basin. The high concentrations of lower thiadiamondoids and occurrence of higher thiadiamondoids and diamondoidthiols support that the oil from well ZS1 C is a product of severe TSR alteration.展开更多
The Kaili Biota of Jianhe County, Guizhou Province is found in a Burgess Shale type of deposits, and as such it provides a key fossil record for studying biotic differentiation following the Cambrian explosion. Macroa...The Kaili Biota of Jianhe County, Guizhou Province is found in a Burgess Shale type of deposits, and as such it provides a key fossil record for studying biotic differentiation following the Cambrian explosion. Macroalgae represent several important groups of primary producers and yet have not been well studied. Here, we report two new forms of macroalgae from the Kaili Biota, including a new genus and species and an indeterminate genus and species. The new genus and species, Parallelphyton tipica, is a heterotrichous alga with thalli composed of a prostrate cardinal axis, and parallel bundles of erect trichomes on the axis. The bifurcation of the trichomes is somewhat similar to the living heterotrichous Fritschiella (Chlorophyta), representing "architectonic differentiation" only known in higher plants as an adaptation to terrestri~ conditions. The indeterminate genus and species consists of an arched, thick, cylindrical major shaft and irregularly spaced, curved lateral branches attached to the major shaft and subdivided into subbranches. The characteristics of the thick and strong major shaft and the lateral branch subdivided branches are analogous to the dichotomous branching of Psilophyton in Protopteridophyta. Thus, the differentiation of the thalli in these two algal forms represents the expression of properties of some higher metaphytes, indicating that the eco- logical differentiation of the macroalgae was well underway at the time of the Kaili Biota.展开更多
Samples of the Cambrian microbial dolomites were collected from Penglaiba section,a well-exposed stratigraphic section in the northwestern area of the Tarim Basin.This study provides an analogue for mediated dolomites...Samples of the Cambrian microbial dolomites were collected from Penglaiba section,a well-exposed stratigraphic section in the northwestern area of the Tarim Basin.This study provides an analogue for mediated dolomites that can precipitate in microbial mats and biofilms.The Cambrian stromatolitic dolomites were studied using high-resolution scanning electron microscopy.The results are as follows:(1)dolomites with 50 nm to 100 nm spherical nanostructures are aggregated into minerals of larger sphericities;(2)nanospherical dolomites of 50 nm to 170 nm diameter are densely arranged as dumbbell-shaped or chained aggregates;(3)silicified filaments,as well as dumbbell-shaped and chain arrangements,are preserved as important microstructures.On the basis of sedimentological,compositional,geochemical,and petrographic data,the microstructures were interpreted as nanoglobules that function as bacteria in the nucleation and filament mineralization stages.The microstructures function as such because they are wrapped in extracellular polymeric substance(EPS)or mucus and mineralized fossils.Silicification accounts for the exceptional preservation of microbial mat structures,including biofilms,as well as filamentous and coccoid microbes.In addition,EPS process is capable of binding different elements,with preference for Si,Mg,and Ca.Such suitable composition favors microbe mineralization and dolomite nucleation on organic substrates.These microscopic structures suggest bacterial mineralization and provide visual evidence for the origin of microbial dolomites.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
Microbial lumps have been found in the Maozhuang Stage(Cambrian Series 2) in the Liangcheng section,Shandong Province,China.Their macro-and micro-scale features distinguish them from other carbonate particles such as ...Microbial lumps have been found in the Maozhuang Stage(Cambrian Series 2) in the Liangcheng section,Shandong Province,China.Their macro-and micro-scale features distinguish them from other carbonate particles such as intraclasts and oncoids.Most lumps have a coarse sand to pebble size.They were mostly rounded during sedimentation or combined to form irregular shapes.A distinct boundary is present between the lumps and the surrounding cement of sparry calcite.The lumps contain either no core at all or several irregular "cores",without a distinct inner texture.They are composed mainly of calcified(micritized) microbes,most likely cyanobacteria.The microbes drilled holes in carbonate grains,after which lumps formed by micritization,cementation,and agglutination by an extracellular polymeric substance(EPS) in a high-energy shallow-marine,subtidal environment.As the lumps are directly related to microbes,they should be considered as microbialites.展开更多
Soil acidity is an important parameter that can regulate ecosystem structure and function.However,a quantitative understanding of the relationships between soil pH and environmental factors remains unavailable.In this...Soil acidity is an important parameter that can regulate ecosystem structure and function.However,a quantitative understanding of the relationships between soil pH and environmental factors remains unavailable.In this study,relationships of soil pH with both climatic and edaphic factors in alpine grasslands on the Tibetan Plateau,China were quantified using data obtained from a regional soil survey during 2001-2004.Our results showed that soil pH decreased along the gradient of both mean annual temperature and precipitation.Likewise,soil pH exhibited consistent negative correlations with soil moisture and silt content.However,soil organic and inorganic carbon contents played opposite roles in shaping patterns of soil pH:the accumulation of soil organic matter led to higher soil acidity,while the existence of soil inorganic matter was favorable for maintaining higher soil alkalinity.The variation partitioning analysis indicated that the combination of climatic and edaphic variables explained 74.3%of the variation in soil acidity.These results suggest that soil pH could be predicted from routinely-measured variables,allowing a robust pedotransfer function to be developed.The pedotransfer function may facilitate land surface models to generate more reliable predictions on ecosystem structure and function around the world.展开更多
基金supported by the National Nature Science Foundation of China (31071965)
文摘A new species, Triphleba conchiformis sp. nov., is described and illustrated. The species differs from other species of the genus by the characters of missing vein R2+3 and shell-like surstylus. The type specimens are deposited in the Liaoning Key Laboratory of Urban Integrated Pest Management and Ecological Security, Shenyang University.
基金funded by the National Natural Science Foundation of China (Grant Nos. 31100360, 31200378, 31000233)
文摘Steller chamaejasme L. (S. chamaejasme for short) is one of the most noxious unpalatable weeds in China, which has been frequently reported its negative interaction (i.e. competition and allelopathy) with other herbaceous species in grasslands. This study compared species diversity, biomass and sexual reproduction of herbaceous plants in meadows with S. chamaejasme and in open meadows without S. ehamaejasme in overgrazing meadows on the Tibetan Plateau in China to determine whether positive facilitation exist between S. chamaejasme and other herbaceous species under livestock's overgrazing. The results showed that there are more herbaceous species in meadows with S. chamaejasme than those in open meadows (35s and30s, respectively). Diversity index and above-ground biomass were also significantly higher in meadows with S. charnaejasme. There were 39% (11/28) of all species with sexual reproduction found in meadows with S. charnaejasme, which was 7 times more than those in open meadows. Our study showed that S. charnaejasme could provide biotic refuge for neighboring plants and preserve plant diversity from livestock's overgrazing in alpine meadows on the Tibetan Plateau. It also suggested that inter-specific facilitation between S. charnaejasme and other herbaceous species may play a key role in overgrazing alpine meadows.
基金Under the auspices of National Natural Science Foundation of China(No.41201445,41103041)National Science and Technology Support Program(No.2012BAJ24B01)National High Technology Research and Development Program of China(No.2009AA12200307)
文摘Accurate wetland delineation is the basis of wetland definition and mapping, and is of great importance for wetland management and research. The Zoige Plateau on the Qinghai-Tibet Plateau was used as a research site for research on alpine wetland delineation. Several studies have analyzed the spatiotemporal pattern and dynamics of these alpine wetlands, but none have addressed the issues of wetland boundaries. The objective of this work was to discriminate the upper boundaries of alpine wetlands by coupling ecological methods and satellite observations. The combination of Landsat 8 images and supervised classification was an effective method for rapid identification of alpine wetlands in the Zoig6 Plateau. Wet meadow was relatively stable compared with hydric soils and wetland hydrology and could be used as a primary indicator for discriminating the upper boundaries of alpine wetlands. A slope of less than 4.5° could be used as the threshold value for wetland delineation. The normalized difference vegetation index (NDVI) in 434 field sites showed that a threshold value of 0.3 could distinguish grasslands from emergent marsh and wet meadow in September. The median normalized difference water index (NDWI) of emergent marsh remained more stable than that of wet meadow and grasslands during the period from September until July of the following year. The index of mean density in wet meadow zones was higher than the emergent and upland zones. Over twice the number of species occurred in the wet meadow zone compared with the emergent zone, and close to the value of upland zone. Alpine wetlands in the three reserves in 2014 covered 1175.19 kin2 with a classification accuracy of 75.6%. The combination of ecological methods and remote sensing technology will play an important role in wetland delineation at medium and small scales. The correct differentiation between wet meadow and grasslands is the key to improving the accuracy of future wetland delineation.
基金Supported by the National Basic Research Program (973 Program) of China (Nos.2009CB421102 and 2005CB422005-01)the Second Scheme of CAS Action Plan for the Development of Western China (No.KZCX2-XB2-06-02)the National Key Technology R&D Program of China (No.2006BAC01A02-01)
文摘Remote sensing data from the Terra Moderate-Resolution Imaging Spectroradiometer (MODIS) and geospatial data were used to estimate grass yield and livestock carrying capacity in the Tibetan Autonomous Prefecture of Golog, Qing-hai, China. The MODIS-derived normalized difference vegetation index (MODIS-NDVI) data were correlated with the aboveground green biomass (AGGB) data from the aboveground harvest method. Regional regression model between the MODIS-NDVI and the common logarithm (LOG10) of the AGGB was significant (r2 = 0.51, P < 0.001), it was, there-fore, used to calculate the maximum carrying capacity in sheep-unit year per hectare. The maximum livestock carrying capacity was then adjusted to the theoretical livestock carrying capacity by the reduction factors (slope, distance to water, and soil erosion). Results indicated that the grassland conditions became worse, with lower aboveground palatable grass yield, plant height, and cover compared with the results obtained in 1981. At the same time, although the actual livestock numbers decreased, they still exceeded the proper theoretical livestock carrying capacity, and overgrazing rates ranged from 27.27% in Darlag County to 293.99% in Baima County. Integrating remote sensing and geographical information system technologies, the spatial and temporal conditions of the alpine grassland, trend, and projected stocking rates could be forecasted for decision making.
基金supported jointly by the National Natural Science Foundation of China (40975039)the National Basic Research Program of China (2006CB400504/ 2009CB421401 and GYHY20070605)
文摘This paper demonstrates regional characteristics, a long-term decreasing trend, and decadal variations in the frequency of cold surge events based on daily mean temperature and daily minimum temperature data in China's Mainland from 1960 to 2008. During these 48 years four high frequency centers of cold surge events were located in Xinjiang, central North China, northeast China, and southeast China. A main frequency peak of cold surge events occurs in autumn for the four regions and another peak is detected in spring over northeast China and southeast China. The regional pattern of cold surge frequencies is in accordance with the perturbation kinetic energy distribution in October December, January, and February April. The long-term decreasing trend ( 0.2 times/decade) of cold surge frequencies in northeast China and decadal variations in China are related to the variations of the temperature difference between southern and northern China in the winter monsoon season; these variations are due to the significant rising of winter temperatures in high latitudes.
基金supported by the National Natural Science Foundation of China (Grant No.41301215)the Natural Science Foundation of Jiangsu Province,China (Grant No.BK20131058)+1 种基金the National Basic Research Program of China(Grant No.2012CB956100)the International Atomic Energy Agency (RC-19018)
文摘Ombrotrophic bogs are faithful archive of atmospheric metal deposition, but the potential for fens to reconstruct environmental change is often underestimated. In this study, some new data on the Pb depositional history in northeast China were provided using two ^210Pb-dated peat sequences from a poor fen in the Fenghuang Mountain of Heilongjiang province. Anthropogenic, detritic and atmospheric soil sources were discriminated using a two-step sequential digestion (weak acid leaching to liberate mobile Pb which is often regarded as anthropogenic Pb, especially for recent samples) and a ratio of unsupported ^210Pb and supported ^210Pb with the logic of that the ^214Pb mainly represents the residual detritus (constant throughout the core) and the unsupported ^210Pb arises from atmospheric fallout. A higher ^210Pb/^214Pb suggests more contributions from atmospheric deposition to the Pb content in the peat, and a ratio of 10 was defined to indicate the boundary between detrific input and atmospheric deposition. The detritic Pb was estimated to be 10-13 mg·kg^-1, the anthropogenic Pb ranged from 10-80 mg·kg^-1, and the atmospheric soil-derived Pb ranged from 〈 5 mg·kg^-1 to 30 mg·kg^-1. The history of anthropogenic Pb pollution over the last 150 years was reconstructed, and the calculated Pb deposition rate (AR Pb) ranged from 5 to 56 mg·m^-2·yr^-1. Using Ti as a reliable reference, the enrichment factor of Pb (EF Pb) relative to the upper continental crust was calculated. Both AR Pb and EF Pb increased with time, especially after the foundation of the People's Republic of China. This is consistent with increasing industrialization and coal burning in the last 60 years in northeast China. The present record of anthropogenic Pb deposition was consistent with the previous reports and an increasing trend of environmental pollution due to anthropogenic activities, in contrasts to Europe and North America which have experienced a major environmental cleanup. For the first time, this work estimates atmospheric Pb deposition via a minerotrophic peat core in China. This will enhance the use of peat archives for studies of environmental change.
文摘The paper analyzes the characteristics of rice production in Heilongjiang Reclamation Area(HRA)and the achievements made through innovative research and practice,evaluates the standardized mode of rice cultivation and technical standards for rice production,which play a key role in guaranteeing the growth of grain total output in Heilongjiang reclamation area and make great contributions to the national grain safety.
文摘It is helpful to improve the seismic design theory of long-span continuous bridges for studying the seismic performance of each cantilever construction state.Taking the Bridge 1 in the north of Changbai-Mountain international tourism resort as an example,the authors studied it in shutdown phase and the cantilever construction process,established the simulation model by using Midas / civil,and analyzed time-history of each construction stage for the bridge.The study shows that long-span bridge cantilever construction in northeastern China can be divided into two-year tasks for construction(suspending in winter).It is needed to think about seismic stability of the cantilever position in shut-down phase of winter.The effect of longitudinal vibration is the most disadvantageous influence to bridge,and its calculation results can provide reference for seismic design of similar bridges in the future.
文摘Alpine-cold regions are characterized as hypoxia,strong wind,heavy rain,cold climate,huge temperature difference between day and night,and vertical climate. All these make it difficult for an emergency rescue when a natural disaster such as earthquake happens. Based on the characteristics of emergency rescue in alpinecold region,several multifunctional protective equipments have been developed by the Quartermaster Equipment Institute of General Logistics Departmen(tGLD)of the Chinese People's Liberation Army(CPLA). These equipments are lightweight,durable and environment adaptable.
基金This research was supported by The National Natural Science Foundation of China (Grant No. 30970176) and The Innovation Scientists and Technicians Troop Construction Projects of Henan Province (Grant No. 094100510018). The authors thanked Yuanji Han, Xueyan Yan, Wangjun Yuan, and Meifang Dong for their assistance.
文摘Low winter temperature is generally recognized as the chief factor limiting the northward distribution of Osmanthus fragrans. O. fragrans has been cultivated in Kaifeng for nearly two decades, yet little is known regarding how well this plant has adapted to the city's cold winter. In a city-wide survey, we periodically examined O. fragrans leaves for visible symptoms of freeze damage, then measured leaf soluble sugar content, leaf electric conductivity, palisade layer thickness/leaf thickness ratio, and spongy layer thickness/leaf thickness ratio of several cultivars. The data thus collected were assessed to determine the cultivars' cold resistance levels. Our results indicate that the northward distribution of O. fragrans may be limited primarily by low spring temperatures rather than low winter temperatures. O. fragrans Sijigui and Huangchuan Jingui are the most cold resistant O. fragrans cultivars in Kaifeng, China.
基金Under the auspices of Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA05060700)Postdoctoral Science Foundation of China(No.2013M530716)
文摘Grazing exclusion is widely adopted in restoring degraded alpine grasslands on the Qinghai-Tibetan Plateau. However, its effectiveness remains poorly understood. In this study, we investigated the effects of grazing exclusion on plant productivity, species diversity and soil organic carbon (SOC) and soil total nitrogen (STN) storage along a transect spanning from east to west of alpine meadows in northern Tibet, China. After six years of grazing exclusion, plant cover, aboveground biomass (AGB), belowground biomass (BGB), SOC and STN were increased, but species diversity indices declined. The enhancement of AGB and SOC caused by grazing exclusion was correlated positively with mean annual precipitation (MAP). Grazing exclusion led to remarkable biomass increase of sedge species, especially Kobresia pygmaea, whereas decrease of biomass in forbs and no obvious change in grass, leguminous and noxious species. Root biomass was concentrated in the near surface layer (10 cm) after grazing exclusion. The effects of grazing exclusion on SOC storage were confined to shallow soil layer in sites with lower MAP. It is indicated that grazing exclusion is an effective measure to increase forage production and enhance soil carbon sequestration in the studied region. The effect is more efficient in sites with higher precipitation. However, the results revealed a tradeoff between vegetation restoration and ecological biodiversity. Therefore, carbon pools recover more quickly than plant biodiversity in the alpine meadows. We suggest that grazing exclusion should be combined with other measures to reconcile grassland restoration and biodiversitv conservation.
文摘High performance concrete originated in the generation of high strength concrete, and it is a new high technology of concrete, is in common with high quality and in concrete. High durability on the perspective of improvement and become, use a lot of high quality raw materials and modern technology, is the main development direction of concrete. Because its comprehensive performance by the superiority of the focus of the society, the strict construction technology in the extensive application in the highway bridge, high performance can the use of concrete can improve the efficiency of its safety and avoid unnecessary accidents
基金supported by the National Natural Science Foundation of China (Grant No. 41772153)State Key Laboratory of Organic Geochemistry, GIGCAS (Grant No. SKLOG2017-02)+1 种基金National Science and Technology Major Project of the Ministry of Science and Technology of China (Grant No. 2017ZX05005-002)SINOPEC Ministry of Science and Technology (Grant No. P16090, P17049-1)
文摘Oil and gas breakthroughs have been achieved in the Zhongshen 1(ZS1) and 1 C(ZS1 C) wells in Cambrian pre-salt from the Tarim Basin in northwest China. However, Middle and Lower Cambrian reservoirs reveal substantial differences in the geochemistry and secondary alteration characteristics between the oils collected from the two wells. High concentrations of thiadiamondoids and diamondoidthiols, including thiatetramantanes, tetramantanethiols, thiapentamantanes, and pentamantanethiols, are detected in the organic sulfur compound fraction of concentrated oil collected from the ZS1 C well, which samples the Lower Cambrian Xiaoerbulake Formation. Higher diamondoids, such as tetramantanes, pentamantanes, hexamantanes, and cyclohexamantane, also occur in the saturate fractions of the concentrated ZS1 C oil. The presence of these compounds is verified by mass spectra analysis and comparison with previous studies. During thermochemical sulfate reduction(TSR), the cage of higher diamondoids is interpreted to open because of sulfur radicals forming open-cage higher diamondoid-like thiols, followed by cyclization that leads to the formation of high thiadiamondoids. Using D_(16)-adamantane as an internal standard, the concentrations of lower diamondoids and thiadiamondoids of non-concentrated Cambrian oil from well ZS1 C are 83874 and8578 μg/g, respectively, which are far higher than Cambrian oil from well ZS1 and most Ordovician oils in the Tarim Basin. The high concentrations of lower thiadiamondoids and occurrence of higher thiadiamondoids and diamondoidthiols support that the oil from well ZS1 C is a product of severe TSR alteration.
基金supported by National Natural Science Foundation of China (Grant No. 40762018)NSFC Innovation Research Group Program (Grant No. 40621002)+2 种基金Mobile Project of Science and Technology of Guizhou Province (Grant No. Gui Ji. 2007-4004)National Basic Research Program of China (Grant No. 2006CB806401)Paleontological Museum of Shenzhen Xianhu Botanical Garden
文摘The Kaili Biota of Jianhe County, Guizhou Province is found in a Burgess Shale type of deposits, and as such it provides a key fossil record for studying biotic differentiation following the Cambrian explosion. Macroalgae represent several important groups of primary producers and yet have not been well studied. Here, we report two new forms of macroalgae from the Kaili Biota, including a new genus and species and an indeterminate genus and species. The new genus and species, Parallelphyton tipica, is a heterotrichous alga with thalli composed of a prostrate cardinal axis, and parallel bundles of erect trichomes on the axis. The bifurcation of the trichomes is somewhat similar to the living heterotrichous Fritschiella (Chlorophyta), representing "architectonic differentiation" only known in higher plants as an adaptation to terrestri~ conditions. The indeterminate genus and species consists of an arched, thick, cylindrical major shaft and irregularly spaced, curved lateral branches attached to the major shaft and subdivided into subbranches. The characteristics of the thick and strong major shaft and the lateral branch subdivided branches are analogous to the dichotomous branching of Psilophyton in Protopteridophyta. Thus, the differentiation of the thalli in these two algal forms represents the expression of properties of some higher metaphytes, indicating that the eco- logical differentiation of the macroalgae was well underway at the time of the Kaili Biota.
基金financially supported by the National Natural Science Foundation of China(Grant No.41402102)Fundamental Research Funds for the Central Universities(Grant No.2652014001)+1 种基金the National Science and Technology Major Project of the Ministry of Science and Technology of China(Grant No.2011ZX05005–002–008HZ)National Basic Research Program of China(Grant No.2011CB201100–03)
文摘Samples of the Cambrian microbial dolomites were collected from Penglaiba section,a well-exposed stratigraphic section in the northwestern area of the Tarim Basin.This study provides an analogue for mediated dolomites that can precipitate in microbial mats and biofilms.The Cambrian stromatolitic dolomites were studied using high-resolution scanning electron microscopy.The results are as follows:(1)dolomites with 50 nm to 100 nm spherical nanostructures are aggregated into minerals of larger sphericities;(2)nanospherical dolomites of 50 nm to 170 nm diameter are densely arranged as dumbbell-shaped or chained aggregates;(3)silicified filaments,as well as dumbbell-shaped and chain arrangements,are preserved as important microstructures.On the basis of sedimentological,compositional,geochemical,and petrographic data,the microstructures were interpreted as nanoglobules that function as bacteria in the nucleation and filament mineralization stages.The microstructures function as such because they are wrapped in extracellular polymeric substance(EPS)or mucus and mineralized fossils.Silicification accounts for the exceptional preservation of microbial mat structures,including biofilms,as well as filamentous and coccoid microbes.In addition,EPS process is capable of binding different elements,with preference for Si,Mg,and Ca.Such suitable composition favors microbe mineralization and dolomite nucleation on organic substrates.These microscopic structures suggest bacterial mineralization and provide visual evidence for the origin of microbial dolomites.
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supported by National Natural Science Foundation of China(Grant No.40972043)Ministry of Education Key Project of Science and Technology(Grant No.211097)+2 种基金Shandong Province Young and Middle-Aged Scientists Research Awards Fund(Grants Nos.BS2009HZ020,2010BSE06022)Science Project of Universities in Shandong Province(Grants Nos.G08LD01,J09LE04)SDUST Research Fund(Grant No.2010KYTD103)
文摘Microbial lumps have been found in the Maozhuang Stage(Cambrian Series 2) in the Liangcheng section,Shandong Province,China.Their macro-and micro-scale features distinguish them from other carbonate particles such as intraclasts and oncoids.Most lumps have a coarse sand to pebble size.They were mostly rounded during sedimentation or combined to form irregular shapes.A distinct boundary is present between the lumps and the surrounding cement of sparry calcite.The lumps contain either no core at all or several irregular "cores",without a distinct inner texture.They are composed mainly of calcified(micritized) microbes,most likely cyanobacteria.The microbes drilled holes in carbonate grains,after which lumps formed by micritization,cementation,and agglutination by an extracellular polymeric substance(EPS) in a high-energy shallow-marine,subtidal environment.As the lumps are directly related to microbes,they should be considered as microbialites.
基金Supported by the National Natural Science Foundation of China(Nos.31170410 and 31322011)
文摘Soil acidity is an important parameter that can regulate ecosystem structure and function.However,a quantitative understanding of the relationships between soil pH and environmental factors remains unavailable.In this study,relationships of soil pH with both climatic and edaphic factors in alpine grasslands on the Tibetan Plateau,China were quantified using data obtained from a regional soil survey during 2001-2004.Our results showed that soil pH decreased along the gradient of both mean annual temperature and precipitation.Likewise,soil pH exhibited consistent negative correlations with soil moisture and silt content.However,soil organic and inorganic carbon contents played opposite roles in shaping patterns of soil pH:the accumulation of soil organic matter led to higher soil acidity,while the existence of soil inorganic matter was favorable for maintaining higher soil alkalinity.The variation partitioning analysis indicated that the combination of climatic and edaphic variables explained 74.3%of the variation in soil acidity.These results suggest that soil pH could be predicted from routinely-measured variables,allowing a robust pedotransfer function to be developed.The pedotransfer function may facilitate land surface models to generate more reliable predictions on ecosystem structure and function around the world.