Gully erosion is the frequent and main form of soil erosion in the black soil area of the northeastern China, which is one of the most important commodity grain production bases in China. It is encroaching upon the fe...Gully erosion is the frequent and main form of soil erosion in the black soil area of the northeastern China, which is one of the most important commodity grain production bases in China. It is encroaching upon the fertile farmland there. Regionalization of gully erosion can reveal the spatial distribution and regularity of the development of gully erosion. Based on the eco-geographical regional background features of the black soil area, this study combined the regionalization with influencing factors of the development of gully erosion. GIS spatial analysis, geostatistical analysis, spatial statistics, reclassification, debris polygon processing and map algebra methods were employed. As a result, the black soil area was divided into 12 subregions. The field survey data on type, length, volume and other characteristics indicators of gully erosion were used to calibrate the results. Then the features of every subregion, such as where the gully erosion is, how serious it is, and why it happens and develops, were expounded. The result is not only an essential prerequisite for gully erosion surveys and monitoring, but also an important basis for gully erosion prevention.展开更多
Background:Habitat loss,fragmentation and decrease of habitat quality caused by urbanization have led to a dramatic decline in biodiversity worldwide.For highly urbanized areas,parks have become“islands”or habitat f...Background:Habitat loss,fragmentation and decrease of habitat quality caused by urbanization have led to a dramatic decline in biodiversity worldwide.For highly urbanized areas,parks have become“islands”or habitat fragments for wildlife.As an important indicator group of urban ecosystem health,the response of birds to urbanization has attracted the global attention of ecologists.Understanding the key factors affecting bird diversity in urbanized environment is crucial to the protection of biodiversity in urban ecosystems.Methods:We used the line-transect method to survey birds in 37 urban parks in Nanjing,China.We also measured a number of park characteristics(area,isolation,shape index,environmental noise,distance to city center,and habitat diversity)that are commonly assumed to influence bird diversity.We then used the information-theoretic multi-model inference approach to determine which park characteristics had significant impacts on bird species richness.Results:We found that park area,habitat diversity and the distance to city center were the best positive predictors of bird species richness in Nanjing urban parks.By contrast,park isolation,park shape and environmental noise had little or no influence on bird diversity.Conclusions:Our study highlights the importance of park area,habitat diversity and the distance to city center in determining bird diversity in Nanjing city parks.Therefore,from a conservation viewpoint,we recommend that large parks with complex and diverse habitats far away from the city center should be retained or constructed to increase bird diversity in urban design and planning.展开更多
The main geological factors controlling the accumulation and yield of marine-facies shale gas reservoirs are the focus of the current shale gas exploration and development research.In this study,the Wufeng-Longmaxi Fo...The main geological factors controlling the accumulation and yield of marine-facies shale gas reservoirs are the focus of the current shale gas exploration and development research.In this study,the Wufeng-Longmaxi Formation in the Dingshan area of southeast Sichuan was investigated.Shale cores underwent laboratory testing,which included the evaluation of total organic carbon(TOC),vitrinite reflectance(Ro),whole-rock X-ray diffraction(XRD),pore permeability,and imaging through field emission scanning electron microscopy(FE-SEM).Based on the results of natural gamma ray spectrum logging,conventional logging,imaging logging,and seismic coherence properties,the exploration and development potential of shale gas in the Dingshan area have been discussed comprehensively.The results showed that(1)layer No.4(WF2-LM4)of the Wufeng-Longmaxi Formation has a Th/U ratio<2 and a Th/K ratio of 3.5–12.Graptolites and pyrite are relatively abundant in the shale core,indicating sub-high-energy and low-energy marine-facies anoxic reducing environments.(2)The organic matter is mainly I-type kerogen with a small amount of II1-type kerogen.There is a good correlation among TOC,Ro,gas content,and brittle minerals;the fracturing property(brittleness)is 57.3%.Organic and inorganic pores are moderately developed.A higher pressure coefficient is correlated with the increase in porosity and the decrease in permeability.(3)The DY1 well of the shale gas reservoir was affected by natural defects and important latestage double destructive effects,and it is poorly preserved.The DY2 well is located far from the Qiyueshan Fault.Large faults are absent,and upward fractures in the Longmaxi Formation are poorly developed.The well is affected by low tectonic deformation intensity,and it is well preserved.(4)The Dingshan area is located at the junction of the two sedimentary centers of Jiaoshiba and Changning.The thickness of the high-quality shale interval(WF2-LM4)is relatively small,which may be an important reason for the unstable production of sh展开更多
基金Under the auspices of National Natural Science Foundation of China(No.41301467,41271416)Special Foundation of National Science and Technology Basic Work of China(No.2013FY112800)
文摘Gully erosion is the frequent and main form of soil erosion in the black soil area of the northeastern China, which is one of the most important commodity grain production bases in China. It is encroaching upon the fertile farmland there. Regionalization of gully erosion can reveal the spatial distribution and regularity of the development of gully erosion. Based on the eco-geographical regional background features of the black soil area, this study combined the regionalization with influencing factors of the development of gully erosion. GIS spatial analysis, geostatistical analysis, spatial statistics, reclassification, debris polygon processing and map algebra methods were employed. As a result, the black soil area was divided into 12 subregions. The field survey data on type, length, volume and other characteristics indicators of gully erosion were used to calibrate the results. Then the features of every subregion, such as where the gully erosion is, how serious it is, and why it happens and develops, were expounded. The result is not only an essential prerequisite for gully erosion surveys and monitoring, but also an important basis for gully erosion prevention.
基金This work was supported by the National Natural Science Foundation of China(Grant No.31971545 and 31770462)Natural Science Foundation of Zhejiang Province(LZ18C030002).
文摘Background:Habitat loss,fragmentation and decrease of habitat quality caused by urbanization have led to a dramatic decline in biodiversity worldwide.For highly urbanized areas,parks have become“islands”or habitat fragments for wildlife.As an important indicator group of urban ecosystem health,the response of birds to urbanization has attracted the global attention of ecologists.Understanding the key factors affecting bird diversity in urbanized environment is crucial to the protection of biodiversity in urban ecosystems.Methods:We used the line-transect method to survey birds in 37 urban parks in Nanjing,China.We also measured a number of park characteristics(area,isolation,shape index,environmental noise,distance to city center,and habitat diversity)that are commonly assumed to influence bird diversity.We then used the information-theoretic multi-model inference approach to determine which park characteristics had significant impacts on bird species richness.Results:We found that park area,habitat diversity and the distance to city center were the best positive predictors of bird species richness in Nanjing urban parks.By contrast,park isolation,park shape and environmental noise had little or no influence on bird diversity.Conclusions:Our study highlights the importance of park area,habitat diversity and the distance to city center in determining bird diversity in Nanjing city parks.Therefore,from a conservation viewpoint,we recommend that large parks with complex and diverse habitats far away from the city center should be retained or constructed to increase bird diversity in urban design and planning.
基金The Open Fund (PLC20180404) of the State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Chengdu University of Technology)The Open Fund (PLN 201718) of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Southwest Petroleum University)The Open Fund(SEC-2018-04)of Collaborative Innovation Center of Shale Gas Resources and Environment (Southwest Petroleum University)
文摘The main geological factors controlling the accumulation and yield of marine-facies shale gas reservoirs are the focus of the current shale gas exploration and development research.In this study,the Wufeng-Longmaxi Formation in the Dingshan area of southeast Sichuan was investigated.Shale cores underwent laboratory testing,which included the evaluation of total organic carbon(TOC),vitrinite reflectance(Ro),whole-rock X-ray diffraction(XRD),pore permeability,and imaging through field emission scanning electron microscopy(FE-SEM).Based on the results of natural gamma ray spectrum logging,conventional logging,imaging logging,and seismic coherence properties,the exploration and development potential of shale gas in the Dingshan area have been discussed comprehensively.The results showed that(1)layer No.4(WF2-LM4)of the Wufeng-Longmaxi Formation has a Th/U ratio<2 and a Th/K ratio of 3.5–12.Graptolites and pyrite are relatively abundant in the shale core,indicating sub-high-energy and low-energy marine-facies anoxic reducing environments.(2)The organic matter is mainly I-type kerogen with a small amount of II1-type kerogen.There is a good correlation among TOC,Ro,gas content,and brittle minerals;the fracturing property(brittleness)is 57.3%.Organic and inorganic pores are moderately developed.A higher pressure coefficient is correlated with the increase in porosity and the decrease in permeability.(3)The DY1 well of the shale gas reservoir was affected by natural defects and important latestage double destructive effects,and it is poorly preserved.The DY2 well is located far from the Qiyueshan Fault.Large faults are absent,and upward fractures in the Longmaxi Formation are poorly developed.The well is affected by low tectonic deformation intensity,and it is well preserved.(4)The Dingshan area is located at the junction of the two sedimentary centers of Jiaoshiba and Changning.The thickness of the high-quality shale interval(WF2-LM4)is relatively small,which may be an important reason for the unstable production of sh
