Relief map of the middle reaches of the Huaihe Valley in 1950s, remote sensing images of 1980 and 2000 are utilized to abstract and interpret land use maps of the study area in different periods and also the distribut...Relief map of the middle reaches of the Huaihe Valley in 1950s, remote sensing images of 1980 and 2000 are utilized to abstract and interpret land use maps of the study area in different periods and also the distribution map of different wetland types on the basis of secondary classification of wetland. Landscape index analysis is applied to analyze and evaluate ecological changes of wetland landscapes in the middle reaches of the Huaihe Valley. The analysis results show that landscape pattern indexes change greatly from 1950s to 1980, but change slightly since 1980. Such a trend demonstrates that wetland landscapes in the study area change from "diversified and complicate" to "unitary and fragmented", wetland system has drastically-reducing components, a great number of transitional zones become extinct, connectivity and heterogeneity of wetland landscapes are largely reduced, integrity and balance of wetland system is broken, as a result, ecological service functions of wetland degrade or cannot be fully utilized.展开更多
Zoige Plateau wetlands are located in the northeastern corner of the Qinghai-Tibet Plateau.The landscape pattern evolution processes in the Zoige Plateau and their driving factors were identified by analyzing the dyna...Zoige Plateau wetlands are located in the northeastern corner of the Qinghai-Tibet Plateau.The landscape pattern evolution processes in the Zoige Plateau and their driving factors were identified by analyzing the dynamic changes in landscape modification and conversion and their dynamic rates of alpine wetlands over the past four decades.The results showed that the landscape conversion between wetlands and non-wetlands mainly occurred during the period from 1966 to 1986.The marsh wetland area converted from lake and river wetlands was larger because of swamping compared to other wetland landscapes.Meanwhile,the larger area of marsh wetlands was also converted to lake wetlands more than other types of wetlands.The modification processes mainly occurred among natural wetland landscapes in the first three periods.Obvious conversions were observed between wetland and nonwetland landscapes(i.e.,forestland,grassland,and other landscapes) in the Zoige Plateau.These natural wetland landscapes such as river,lake and marsh wetlands showed a net loss over the past four decades,whereas artificial wetland landscapes(i.e.,paddy field and reservoir and pond wetlands) showed a net decrease.The annual dynamic rate of the whole wetland landscape was 0.72%,in which the annual dynamic rate of river wetlands was the highest,followed by lake wetlands,while marsh wetlands had the lowest dynamic rate.The integrated landscape dynamic rate showed a decreasing trend in the first three periods.The changes in wetland landscape patterns were comprehensively controlled by natural factors and human activities,especially human activities play an important role in changing wetland landscape patterns.展开更多
The landscape pattern of Beijing wetlands has undergone a significant change as a result of natural and artificial elements.Supported by remote sensing and GIS technology,using multi-temporal TM images from 1984 to 20...The landscape pattern of Beijing wetlands has undergone a significant change as a result of natural and artificial elements.Supported by remote sensing and GIS technology,using multi-temporal TM images from 1984 to 2008 in Beijing,this paper analyzed the dynamic characteristics of wetlands landscape pattern through selected typical indices including patch area,patch average area,fractal dimension index,diversity,dominance,contagion indices and the spatial centroids of each wetlands type were calculated.Finally,the paper explored the evolution mode and driving factors of wetland landscape pattern.The results were obtained as follows：the total wetland area increased during the period 1984-1996,then decline from 1996 to 2004.The wetland area in 1994 accounted for only 47.37% of that in 2004.The proportion of artificial wetland area was larger than that of natural wetland.The proportion of reservoir wetland was 33.50% to 53.73% and had the maximum average area.pond and paddy field wetland type with the least average area accounted for 16.46% to 45.09% of the total wetland area.The driving forces of the natural river wetland were mainly natural elements;its fractal dimension index was greater than the others.The Shannon diversity index of wetland landscape increased from 1.11 in 1992 to 1.34 in 2004,indicating that the difference between proportions of each wetland type decreased and areas of each wetland type were evenly distributed.The contagion index went down from 65.59 to 58.41,indicating that the connectivity degraded.Miyun Reservoir had the largest area and its area change had a great impact on the location of the centroid.Wetland resources degenerated gradually from the joint effects of natural and artificial factors.During the period 2006-2008,the precipitation increased and the drought condition was relieved.The government implemented series of positive policies to save water resources,and the wetland area increased.展开更多
Quantifying correlation between the spatial patterns of natural wetland plants and environmental gradient gives better understanding of wetland habitats, which is the fundamental for the strategy making on the protect...Quantifying correlation between the spatial patterns of natural wetland plants and environmental gradient gives better understanding of wetland habitats, which is the fundamental for the strategy making on the protection and restoration of natural wetlands. In this study, the spatial patterns of wetland plants and the environmental gradient of wetland habitats were assessed in the Honghe National Nature Reserve （HNNR） in Northeast China, a wetland of international importance on the Ramsar list. Biophysical parameters’ values of wetland plants were obtained by field sampling methods, and wetland mapping at the community scale was completed using remote sensing techniques. Digital delineation of the surface water system, hydrological zoning and wetness index were produced by spatial analysis methods in Geographic Information System. An ecological ordination method and two clustering methods were used to quantify the relationship between the spatial distribution patterns of wetland plants and the corresponding environmental gradients. Such quantitative analyses also present the specific diversity of different types of wetland plants based on the environmental attributes of their habitats. With the support from modern geo-information techniques, the experimental results indicate how four ecotypes of wetland plants spatially transit from forest swamp, shrub wetland and meadow into marsh wetland with increasing wetness index and water table. And they also show how wetland spatial distribution patterns are controlled by an environmental gradient of wetness. Another key finding of this research work is that our results present the exact fundamental differences between marsh and non-marsh plants of 11 wetland plant communities within the core study area. Hence, this case study gives a good sample for better understanding of the complex correlation between the spatial patterns of wetland plants and their environmental attributes using advanced digital analysis methods. It is also useful to show how to integrate geoinformatic techniques with statistical analysis methods based on the field data base.展开更多
The Yellow River Delta wetland is the youngest wetland ecosystem in China's warm temperate zone. To better understand how its landscape pattern has changed over time and the underlying factors responsible, this st...The Yellow River Delta wetland is the youngest wetland ecosystem in China's warm temperate zone. To better understand how its landscape pattern has changed over time and the underlying factors responsible, this study analyzed the dynamic changes of wetlands using five Landsat series of images, namely MSS(Mulri Spectral Scanner), TM(Thematic Mapper), and OLI(Operational Land Imager) sensors in 1976, 1986, 1996, 2006, and 2016. Object-oriented classification and the combination of spatial and spectral features and both the Normalized Difference Vegetation Index(NDVI) and Normalized Difference Water Index(NDWI), as well as brightness characteristic indices, were used to classify the images in eCognition software. Landscape pattern changes in the Yellow River Delta over the past 40 years were then delineated using transition matrix and landscape index methods. Results show that: 1) from1976 to 2016, the total area of wetlands in the study area decreased from 2594.76 to 2491.79 km^2, while that of natural wetlands decreased by 954.03 km^2 whereas human-made wetlands increased by 851.06 km^2. 2) The transformation of natural wetlands was extensive: 31.34% of those covered by Suaeda heteropteras were transformed into reservoirs and ponds, and 24.71% with Phragmites australis coverage were transformed into dry farmland. Some human-made wetlands were transformed into non-wetlands types: 1.55% of reservoirs and ponds became construction land, and likewise 21.27% were transformed into dry farmland. 3) From 1976 to 2016, as the intensity of human activities increased, the number of landscape types in the study area continuously increased. Patches were scattered and more fragmented. The whole landscape became more complex. In short, over the past 40 years, the wetlands of the Yellow River Delta have been degraded, with the area of natural wetlands substantially reduced. Human activities were the dominant forces driving these changes in the Yellow River Delta.展开更多
Cumulative effects on wetland soils under different cultivation patterns were analyzed in the experimental fields of the Ecological Experimental Station of Mire-wetlands in Sanjiang Plain. The results suggested that t...Cumulative effects on wetland soils under different cultivation patterns were analyzed in the experimental fields of the Ecological Experimental Station of Mire-wetlands in Sanjiang Plain. The results suggested that the paddy field combined with the glebe to act on the soil environment. Under the combination of natural and anthropological factors, the cultivation of the paddy field and the glebe obviously related with different kinds of fertility factors of soil. The remarkable relation among organic matter, total nitrogen and available nitrogen reflected the fertilization of the soil at some extent.展开更多
The influence of anthropogenic activities,especially artificial dykes,on the coastal wetland landscape is now considered as a serious problem to the coastal ecosystem.It is important and necessary to analyze changes o...The influence of anthropogenic activities,especially artificial dykes,on the coastal wetland landscape is now considered as a serious problem to the coastal ecosystem.It is important and necessary to analyze changes of coastal landscape pattern under the influence of artificial dykes for the protection and management of coastal wetland.Our study aimed to reveal the quantitative characteristics of the coastal wetland landscape and its spatial-temporal dynamics under the influence of artificial dykes in the Yellow River delta(YRD).It was analyzed by the methods of the statistical analysis of landscape structure,five selected landscape indices and the changes of spatial centroids of three typical wetland types,including reed marshes,tidal fiats and aquaculture-salt fields.The results showed that:(1)Reduction of wetland area,especially the degradation of natural wetlands,had been the principal problem since the dykes were constructed in the YRD.The dykes created conditions for the development of artificial wetlands.However,the new born artificial wetlands were still less than the vanished natural wetlands.(2)Compared with the open area,the building of artificial dykes significantly speeded up the changes of landscape patterns and the aggravation of the landscape fragmentation in the closed area.(3)The changes of area-weighted centroids of three typical wetland landscapes were greatly affected by dykes,and the movement of the centroid of the aquaculture-salt field was very sensitive to the dykes constructed in the corresponding period.展开更多
By using TM remote sensing images of Baiyangdian Wetland in 1989,1999,2003 and 2004,taking the water area between Anxin County and Cangzhou where most of Baiyangdian Wetland water body lies for landscape classificatio...By using TM remote sensing images of Baiyangdian Wetland in 1989,1999,2003 and 2004,taking the water area between Anxin County and Cangzhou where most of Baiyangdian Wetland water body lies for landscape classification,changes in landscape pattern of Baiyangdian before and after the water supplement were analyzed with landscape indexes calculated by Fragstats3.3. The results showed that after the water supplement,from the perspective of landscape cell index,fractal dimension of major ecosystems in Baiyangdian decreased to some extent;from the perspective of landscape diversity index,diversity index of the study region also decreased,which demonstrated that ecosystem diversity in this region reduced,land cover grew to simplification;and the decreasing evenness degree of the study region also showed the uneven development of its ecosystems. That is to say,water supplement has brought favorable ecological changes to the eco-environment of Baiyangdian,which has further optimized the health condition of ecosystems in this region.展开更多
The quantitative research of wetland landscape fragmentation in the middle reaches of the Heihe River is important for the wetland and oasis sustainable development in the Hexi Corridor. Based on the data of remote se...The quantitative research of wetland landscape fragmentation in the middle reaches of the Heihe River is important for the wetland and oasis sustainable development in the Hexi Corridor. Based on the data of remote sensing and GIS, we constructed the type change tracker model with sliding window technique and spatially mor- phological rule. The suitable scale and optimum scale of the fragmentation model of wetland landscape in the middle reaches of the Heihe River were determined by the area frequency statistics method, Chi-square distribution normal- ized scale variance, fractal dimension and diversity index. By integrating type change tracker model and the optimum scale with GIS spatial analysis, the spatial distribution characteristics of wetland landscape fragmentation in different periods and the related spatial-temporal change process were clarified. The results showed that （1） the type change tracker model, which analyzes the spatial pattern of wetland fragmentation on the pixel level, is better than the tradi- tional wetland fragmentation analysis on the landscape and patch levels; （2） The suitable scale for the wetland frag- mentation ranged from 150 rex150 m to 450 mx450 m and the optimum scale was 250 mx250 m in the middle reaches of the Heihe River; and （3） In the past 35 years, the total wetland area decreased by 23.2% and the frag- mentatJon of wetland markedly increased in the middle reaches of the Heihe River. The areas of core wetlands re- duced by 12.8% and the areas of perforated, edge and patch wetlands increased by 0.8%, 3.1% and 8.9%, respec- tively. The process of wetland fragmentation in the research region showed the order of core wetland, perforated or edge wetland, patch wetland or non-wetland. The results of this study would provide a reference for the protection, utilization and restoration of limited wetland resources and for the sustainable development of the regional eco-environment in the Heihe River Basin.展开更多
We selected four kinds of land use types from Caohai wetlands of Guizhou plateau（a total number of 32 soil profiles） to study the distribution characteristics of organic carbon content in soil. With different ways o...We selected four kinds of land use types from Caohai wetlands of Guizhou plateau（a total number of 32 soil profiles） to study the distribution characteristics of organic carbon content in soil. With different ways of land use, the organic carbon content of soil profiles and organic carbon density show the tendency of decreasing firstly and then increasing from top to bottom. With the increase of depth, the vertical difference becomes smaller first and then starts increasing. Land reclamation reduces the soil organic carbon content and density, changing its distribution structure in topsoil. The average content of organic carbon in Caohai wetlands are as follows： lake bed silt [ marsh wetland [ farmland [ woodland, the average organic carbon content of lake bed silt, marsh wetland,farmland and woodland are 16.40, 2.94, 1.81 and 1.08 %,respectively. Land reclamation reduces the organic carbon content of soil, therefore the conversion of cultivated lands to wetlands and the increase of forest coverage will help to fix the organic carbon in soil and increase its reserves.展开更多
The researches about reed growth were mainly concentrated on seasonal dynamics, investigation of reed resource, and comparison of different ecotypes of reed. By means of fractal geometric theory of non linear science...The researches about reed growth were mainly concentrated on seasonal dynamics, investigation of reed resource, and comparison of different ecotypes of reed. By means of fractal geometric theory of non linear science, the fractal character of growth pattern of reed, for the purpose of quantitatively exploring the mechanism of reed growth was studied. The way to calculate fractal dimension of reed growth is box dimension (BD) and information dimension (ID). The results showed that the difference between two samplings in May and those among three samplings in June and later were not remarkable for both BD or ID. It was noted that the difference between samplings in and after May is significant. It was demonstrated that the fractal dimension of size distribution of reed ranged from 0 6235 to 0 8761 The distribution pattern could be statistically divided as two significant periods: the size of reed is quite well distributed at the beginning of reed growth (fractal dimension>0 8), but is irregular in the middle and later growth season (fractal dimension<0 7). These results are benefit to reach the goal of rational use of reed resources and to protect the biodiversity in wetland ecosystem.展开更多
The effect of spatial pattern on the nutrient reduction is investigated based on the spatial simulation model developed for the study area of the Liaohe Delta, China. Four scenarios are designed to test the effect of ...The effect of spatial pattern on the nutrient reduction is investigated based on the spatial simulation model developed for the study area of the Liaohe Delta, China. Four scenarios are designed to test the effect of different landscape components on the nutrient reduction in the reed marsh: Canal density, reed area size, reed area shrinking pattern, and pumping station position. Based on a spatial model designed for the study area, the nutrient reduction in each case of these scenarios is simulated. The results indicate that each factor brings less than 10% change in the total nutrient reduction rate. More canals will not help much to improve nutrient reduction. Smaller areas are more efficient than larger ones. The shrinkage pattern is better than others in keeping a higher nutrient reduction rate. It is also more efficient to keep the pumping station near the border of the area to be irrigated. These conclusions provide theoretical supports to strategy makers for local land use planning, and contribute to the understanding of the relationship between landscape patterns and functions.展开更多
In this paper, the landscape design of the Bailuxi Wetland in University of Sanya was studied by using the research method of “survey—analysis—design”. The questionnaire survey, field observation and landscape pat...In this paper, the landscape design of the Bailuxi Wetland in University of Sanya was studied by using the research method of “survey—analysis—design”. The questionnaire survey, field observation and landscape pattern analysis were used to analyze the landscape pattern of the Bailuxi Wetland as well as the characteristics and problems of the six subsystems of green space, activity, road, animal, plant, and sound. Then the overall structure and function design of the Bailuxi Wetland landscape, the optimization adjustment of the landscape pattern, the optimization design of the subsystem, and the relationship design between human and the animal, plant, and sound systems were proposed. This study is dedicated to providing effective advice on the planning and design of campus wetland landscapes, with a view to providing examples for the planning and design of campus wetland landscapes. The research indicates that:① Scientific and rational spatial structure and functional layout planning are prerequisites for the sustainable development of wetland landscapes;② the balanced development of subsystems in the campus wetland system is a necessary condition for maintaining the rationality of the campus landscape pattern;③ the degree of harmony between humans and animals, plants, and sounds affects the ecological sustainability of campus wetland landscapes.展开更多
In the case of increasing fragmentation of wetlands, the study of the relationship between wetland landscape characteristics and total nitrogen(TN) in water is of great significance to reveal the mechanism of wetland ...In the case of increasing fragmentation of wetlands, the study of the relationship between wetland landscape characteristics and total nitrogen(TN) in water is of great significance to reveal the mechanism of wetland water purification. Taking the Naoli River(NR) wetlands in Northeast China as the research object, 10 uniformly distributed sampling sites in the study area were sampled in August 2015 to test the TN concentration and interpret the images of NR wetlands in the same period. Taking the sampling site as the control point, the whole wetlands were divided into 10 regions, and the landscape index of each region was extracted. In order to reveal whether the landscape characteristics are related to the TN concentration in the wetlands water body, the landscape index and the TN concentration in the control point water body were analyzed by correlation analysis, step-by-step elimination analysis and path analysis to reveal whether the landscape characteristics are related to the TN concentration under wetlands receiving agricultural drainages. The results showed that the correlation coefficients between four area indexes or eight shape indexes and TN concentration did not reach a significant correlation level(P > 0.05), indicating that TN removal was not only determined by a single landscape index. The path coefficient of edge density(ED) index is –0.41, indicating that wetland patch connectivity is the primary factor of TN removal, and there is no relationship between the larger patch area and the higher TN removal. The removal of TN in wetlands is restricted by the synergistic effect of landscape area and shape characteristics.展开更多
基金Supported by National Basic Research Program of China:"Coupling Mechanism of Aquatic Eco-process and Pattern of Wetland System"(2006CB403301)Doctoral Initiation Project of Hanshan Normal University:"Study on Evolution of Wetland Landscape Pattern in the Middle Reaches of the Huaihe Valley"~~
文摘Relief map of the middle reaches of the Huaihe Valley in 1950s, remote sensing images of 1980 and 2000 are utilized to abstract and interpret land use maps of the study area in different periods and also the distribution map of different wetland types on the basis of secondary classification of wetland. Landscape index analysis is applied to analyze and evaluate ecological changes of wetland landscapes in the middle reaches of the Huaihe Valley. The analysis results show that landscape pattern indexes change greatly from 1950s to 1980, but change slightly since 1980. Such a trend demonstrates that wetland landscapes in the study area change from "diversified and complicate" to "unitary and fragmented", wetland system has drastically-reducing components, a great number of transitional zones become extinct, connectivity and heterogeneity of wetland landscapes are largely reduced, integrity and balance of wetland system is broken, as a result, ecological service functions of wetland degrade or cannot be fully utilized.
基金financially supported by National Natural Science Foundation of China(Grant No. 51179006)China National Funds for Distinguished Young Scientists (Grant No.51125035)+2 种基金National Science Foundation for Innovative Research Group (Grant No. 51121003)the Program for New Century Excellent Talents in University (NECT-10-0235)the Fok Ying Tung Foundation (Grant No. 132009)
文摘Zoige Plateau wetlands are located in the northeastern corner of the Qinghai-Tibet Plateau.The landscape pattern evolution processes in the Zoige Plateau and their driving factors were identified by analyzing the dynamic changes in landscape modification and conversion and their dynamic rates of alpine wetlands over the past four decades.The results showed that the landscape conversion between wetlands and non-wetlands mainly occurred during the period from 1966 to 1986.The marsh wetland area converted from lake and river wetlands was larger because of swamping compared to other wetland landscapes.Meanwhile,the larger area of marsh wetlands was also converted to lake wetlands more than other types of wetlands.The modification processes mainly occurred among natural wetland landscapes in the first three periods.Obvious conversions were observed between wetland and nonwetland landscapes(i.e.,forestland,grassland,and other landscapes) in the Zoige Plateau.These natural wetland landscapes such as river,lake and marsh wetlands showed a net loss over the past four decades,whereas artificial wetland landscapes(i.e.,paddy field and reservoir and pond wetlands) showed a net decrease.The annual dynamic rate of the whole wetland landscape was 0.72%,in which the annual dynamic rate of river wetlands was the highest,followed by lake wetlands,while marsh wetlands had the lowest dynamic rate.The integrated landscape dynamic rate showed a decreasing trend in the first three periods.The changes in wetland landscape patterns were comprehensively controlled by natural factors and human activities,especially human activities play an important role in changing wetland landscape patterns.
基金Technology Plan Project of Beijing,No.D08040600580801International S&T Cooperation Project,No.2010DFA92400Project of Beijing Municipal Commission of Education,No.115304535
文摘The landscape pattern of Beijing wetlands has undergone a significant change as a result of natural and artificial elements.Supported by remote sensing and GIS technology,using multi-temporal TM images from 1984 to 2008 in Beijing,this paper analyzed the dynamic characteristics of wetlands landscape pattern through selected typical indices including patch area,patch average area,fractal dimension index,diversity,dominance,contagion indices and the spatial centroids of each wetlands type were calculated.Finally,the paper explored the evolution mode and driving factors of wetland landscape pattern.The results were obtained as follows：the total wetland area increased during the period 1984-1996,then decline from 1996 to 2004.The wetland area in 1994 accounted for only 47.37% of that in 2004.The proportion of artificial wetland area was larger than that of natural wetland.The proportion of reservoir wetland was 33.50% to 53.73% and had the maximum average area.pond and paddy field wetland type with the least average area accounted for 16.46% to 45.09% of the total wetland area.The driving forces of the natural river wetland were mainly natural elements;its fractal dimension index was greater than the others.The Shannon diversity index of wetland landscape increased from 1.11 in 1992 to 1.34 in 2004,indicating that the difference between proportions of each wetland type decreased and areas of each wetland type were evenly distributed.The contagion index went down from 65.59 to 58.41,indicating that the connectivity degraded.Miyun Reservoir had the largest area and its area change had a great impact on the location of the centroid.Wetland resources degenerated gradually from the joint effects of natural and artificial factors.During the period 2006-2008,the precipitation increased and the drought condition was relieved.The government implemented series of positive policies to save water resources,and the wetland area increased.
基金Knowledge Innovation Program of the Chinese Academy of Sciences,No.KZCX2-YW-Q06-03 National Natural Science Foundation of China,No.40871241
文摘Quantifying correlation between the spatial patterns of natural wetland plants and environmental gradient gives better understanding of wetland habitats, which is the fundamental for the strategy making on the protection and restoration of natural wetlands. In this study, the spatial patterns of wetland plants and the environmental gradient of wetland habitats were assessed in the Honghe National Nature Reserve （HNNR） in Northeast China, a wetland of international importance on the Ramsar list. Biophysical parameters’ values of wetland plants were obtained by field sampling methods, and wetland mapping at the community scale was completed using remote sensing techniques. Digital delineation of the surface water system, hydrological zoning and wetness index were produced by spatial analysis methods in Geographic Information System. An ecological ordination method and two clustering methods were used to quantify the relationship between the spatial distribution patterns of wetland plants and the corresponding environmental gradients. Such quantitative analyses also present the specific diversity of different types of wetland plants based on the environmental attributes of their habitats. With the support from modern geo-information techniques, the experimental results indicate how four ecotypes of wetland plants spatially transit from forest swamp, shrub wetland and meadow into marsh wetland with increasing wetness index and water table. And they also show how wetland spatial distribution patterns are controlled by an environmental gradient of wetness. Another key finding of this research work is that our results present the exact fundamental differences between marsh and non-marsh plants of 11 wetland plant communities within the core study area. Hence, this case study gives a good sample for better understanding of the complex correlation between the spatial patterns of wetland plants and their environmental attributes using advanced digital analysis methods. It is also useful to show how to integrate geoinformatic techniques with statistical analysis methods based on the field data base.
基金Under the auspices of National Key Research&Development Program of China(No.2017YFC0505901,2017YFA0604904)
文摘The Yellow River Delta wetland is the youngest wetland ecosystem in China's warm temperate zone. To better understand how its landscape pattern has changed over time and the underlying factors responsible, this study analyzed the dynamic changes of wetlands using five Landsat series of images, namely MSS(Mulri Spectral Scanner), TM(Thematic Mapper), and OLI(Operational Land Imager) sensors in 1976, 1986, 1996, 2006, and 2016. Object-oriented classification and the combination of spatial and spectral features and both the Normalized Difference Vegetation Index(NDVI) and Normalized Difference Water Index(NDWI), as well as brightness characteristic indices, were used to classify the images in eCognition software. Landscape pattern changes in the Yellow River Delta over the past 40 years were then delineated using transition matrix and landscape index methods. Results show that: 1) from1976 to 2016, the total area of wetlands in the study area decreased from 2594.76 to 2491.79 km^2, while that of natural wetlands decreased by 954.03 km^2 whereas human-made wetlands increased by 851.06 km^2. 2) The transformation of natural wetlands was extensive: 31.34% of those covered by Suaeda heteropteras were transformed into reservoirs and ponds, and 24.71% with Phragmites australis coverage were transformed into dry farmland. Some human-made wetlands were transformed into non-wetlands types: 1.55% of reservoirs and ponds became construction land, and likewise 21.27% were transformed into dry farmland. 3) From 1976 to 2016, as the intensity of human activities increased, the number of landscape types in the study area continuously increased. Patches were scattered and more fragmented. The whole landscape became more complex. In short, over the past 40 years, the wetlands of the Yellow River Delta have been degraded, with the area of natural wetlands substantially reduced. Human activities were the dominant forces driving these changes in the Yellow River Delta.
基金Supported by Chinese Youth Natural Sciences Fund Project(40501030)
文摘Cumulative effects on wetland soils under different cultivation patterns were analyzed in the experimental fields of the Ecological Experimental Station of Mire-wetlands in Sanjiang Plain. The results suggested that the paddy field combined with the glebe to act on the soil environment. Under the combination of natural and anthropological factors, the cultivation of the paddy field and the glebe obviously related with different kinds of fertility factors of soil. The remarkable relation among organic matter, total nitrogen and available nitrogen reflected the fertilization of the soil at some extent.
基金supported by the Open Fund for Field Stations of Institute of Geographic Sciences and Natural Resources Research,CAS and the Ocean Public Welfare Scientific Research Project(Grant No.201105020)
文摘The influence of anthropogenic activities,especially artificial dykes,on the coastal wetland landscape is now considered as a serious problem to the coastal ecosystem.It is important and necessary to analyze changes of coastal landscape pattern under the influence of artificial dykes for the protection and management of coastal wetland.Our study aimed to reveal the quantitative characteristics of the coastal wetland landscape and its spatial-temporal dynamics under the influence of artificial dykes in the Yellow River delta(YRD).It was analyzed by the methods of the statistical analysis of landscape structure,five selected landscape indices and the changes of spatial centroids of three typical wetland types,including reed marshes,tidal fiats and aquaculture-salt fields.The results showed that:(1)Reduction of wetland area,especially the degradation of natural wetlands,had been the principal problem since the dykes were constructed in the YRD.The dykes created conditions for the development of artificial wetlands.However,the new born artificial wetlands were still less than the vanished natural wetlands.(2)Compared with the open area,the building of artificial dykes significantly speeded up the changes of landscape patterns and the aggravation of the landscape fragmentation in the closed area.(3)The changes of area-weighted centroids of three typical wetland landscapes were greatly affected by dykes,and the movement of the centroid of the aquaculture-salt field was very sensitive to the dykes constructed in the corresponding period.
基金Sponsored by Scientific and Research Foundation of Yunnan Provincial Education Department (08Y0303)S&T Innovation Team Project of Bio-diversity Protection of Qujing Normal University~~
文摘By using TM remote sensing images of Baiyangdian Wetland in 1989,1999,2003 and 2004,taking the water area between Anxin County and Cangzhou where most of Baiyangdian Wetland water body lies for landscape classification,changes in landscape pattern of Baiyangdian before and after the water supplement were analyzed with landscape indexes calculated by Fragstats3.3. The results showed that after the water supplement,from the perspective of landscape cell index,fractal dimension of major ecosystems in Baiyangdian decreased to some extent;from the perspective of landscape diversity index,diversity index of the study region also decreased,which demonstrated that ecosystem diversity in this region reduced,land cover grew to simplification;and the decreasing evenness degree of the study region also showed the uneven development of its ecosystems. That is to say,water supplement has brought favorable ecological changes to the eco-environment of Baiyangdian,which has further optimized the health condition of ecosystems in this region.
基金supported by the National Natural Science Foundation of China (41261047, 41201196, 41271133)the Youth Teacher Scientific Capability Promoting Project of Northwest Normal University (NWNU-LKQN-11-11)
文摘The quantitative research of wetland landscape fragmentation in the middle reaches of the Heihe River is important for the wetland and oasis sustainable development in the Hexi Corridor. Based on the data of remote sensing and GIS, we constructed the type change tracker model with sliding window technique and spatially mor- phological rule. The suitable scale and optimum scale of the fragmentation model of wetland landscape in the middle reaches of the Heihe River were determined by the area frequency statistics method, Chi-square distribution normal- ized scale variance, fractal dimension and diversity index. By integrating type change tracker model and the optimum scale with GIS spatial analysis, the spatial distribution characteristics of wetland landscape fragmentation in different periods and the related spatial-temporal change process were clarified. The results showed that （1） the type change tracker model, which analyzes the spatial pattern of wetland fragmentation on the pixel level, is better than the tradi- tional wetland fragmentation analysis on the landscape and patch levels; （2） The suitable scale for the wetland frag- mentation ranged from 150 rex150 m to 450 mx450 m and the optimum scale was 250 mx250 m in the middle reaches of the Heihe River; and （3） In the past 35 years, the total wetland area decreased by 23.2% and the frag- mentatJon of wetland markedly increased in the middle reaches of the Heihe River. The areas of core wetlands re- duced by 12.8% and the areas of perforated, edge and patch wetlands increased by 0.8%, 3.1% and 8.9%, respec- tively. The process of wetland fragmentation in the research region showed the order of core wetland, perforated or edge wetland, patch wetland or non-wetland. The results of this study would provide a reference for the protection, utilization and restoration of limited wetland resources and for the sustainable development of the regional eco-environment in the Heihe River Basin.
基金supported by Project of Guizhou Special Funds for High-level Personnel (Grant Number TZJF-2011-44)Program for New Century Excellent Talents in University (NCET-12-0659)Project of Guizhou Governor Capital Fund (Guizhou province designed cooperative [2012]71)
文摘We selected four kinds of land use types from Caohai wetlands of Guizhou plateau（a total number of 32 soil profiles） to study the distribution characteristics of organic carbon content in soil. With different ways of land use, the organic carbon content of soil profiles and organic carbon density show the tendency of decreasing firstly and then increasing from top to bottom. With the increase of depth, the vertical difference becomes smaller first and then starts increasing. Land reclamation reduces the soil organic carbon content and density, changing its distribution structure in topsoil. The average content of organic carbon in Caohai wetlands are as follows： lake bed silt [ marsh wetland [ farmland [ woodland, the average organic carbon content of lake bed silt, marsh wetland,farmland and woodland are 16.40, 2.94, 1.81 and 1.08 %,respectively. Land reclamation reduces the organic carbon content of soil, therefore the conversion of cultivated lands to wetlands and the increase of forest coverage will help to fix the organic carbon in soil and increase its reserves.
文摘The researches about reed growth were mainly concentrated on seasonal dynamics, investigation of reed resource, and comparison of different ecotypes of reed. By means of fractal geometric theory of non linear science, the fractal character of growth pattern of reed, for the purpose of quantitatively exploring the mechanism of reed growth was studied. The way to calculate fractal dimension of reed growth is box dimension (BD) and information dimension (ID). The results showed that the difference between two samplings in May and those among three samplings in June and later were not remarkable for both BD or ID. It was noted that the difference between samplings in and after May is significant. It was demonstrated that the fractal dimension of size distribution of reed ranged from 0 6235 to 0 8761 The distribution pattern could be statistically divided as two significant periods: the size of reed is quite well distributed at the beginning of reed growth (fractal dimension>0 8), but is irregular in the middle and later growth season (fractal dimension<0 7). These results are benefit to reach the goal of rational use of reed resources and to protect the biodiversity in wetland ecosystem.
基金National Natural Science Foundation of China, NSFC 49631040, 40001002 Wageningen Agricultural University, the Netherlands Co-s
文摘The effect of spatial pattern on the nutrient reduction is investigated based on the spatial simulation model developed for the study area of the Liaohe Delta, China. Four scenarios are designed to test the effect of different landscape components on the nutrient reduction in the reed marsh: Canal density, reed area size, reed area shrinking pattern, and pumping station position. Based on a spatial model designed for the study area, the nutrient reduction in each case of these scenarios is simulated. The results indicate that each factor brings less than 10% change in the total nutrient reduction rate. More canals will not help much to improve nutrient reduction. Smaller areas are more efficient than larger ones. The shrinkage pattern is better than others in keeping a higher nutrient reduction rate. It is also more efficient to keep the pumping station near the border of the area to be irrigated. These conclusions provide theoretical supports to strategy makers for local land use planning, and contribute to the understanding of the relationship between landscape patterns and functions.
基金Sponsored by Hainan Natural Science Fund(417179)the Key Project of Teaching Reform Research in Colleges and Universities in Hainan Province(HNJG2019ZD-24)the National Undergraduate Innovation and Entrepreneurship Training Program(201813892560)
文摘In this paper, the landscape design of the Bailuxi Wetland in University of Sanya was studied by using the research method of “survey—analysis—design”. The questionnaire survey, field observation and landscape pattern analysis were used to analyze the landscape pattern of the Bailuxi Wetland as well as the characteristics and problems of the six subsystems of green space, activity, road, animal, plant, and sound. Then the overall structure and function design of the Bailuxi Wetland landscape, the optimization adjustment of the landscape pattern, the optimization design of the subsystem, and the relationship design between human and the animal, plant, and sound systems were proposed. This study is dedicated to providing effective advice on the planning and design of campus wetland landscapes, with a view to providing examples for the planning and design of campus wetland landscapes. The research indicates that:① Scientific and rational spatial structure and functional layout planning are prerequisites for the sustainable development of wetland landscapes;② the balanced development of subsystems in the campus wetland system is a necessary condition for maintaining the rationality of the campus landscape pattern;③ the degree of harmony between humans and animals, plants, and sounds affects the ecological sustainability of campus wetland landscapes.
基金Under the auspices of National Natural Science Foundations of China(No.41620104005,31500307,41601263,41771120)Technology Development Program of Jilin Province(No.20180101082JC,20180520085JC,20190201256JC,20190201018JC)+1 种基金Natural Science Foundation of Changchun Normal University(No.2016-009)Northeast Institute of Geography and Agroecology,Chinese Academy of Sciences(No.IGA-135-05)
文摘In the case of increasing fragmentation of wetlands, the study of the relationship between wetland landscape characteristics and total nitrogen(TN) in water is of great significance to reveal the mechanism of wetland water purification. Taking the Naoli River(NR) wetlands in Northeast China as the research object, 10 uniformly distributed sampling sites in the study area were sampled in August 2015 to test the TN concentration and interpret the images of NR wetlands in the same period. Taking the sampling site as the control point, the whole wetlands were divided into 10 regions, and the landscape index of each region was extracted. In order to reveal whether the landscape characteristics are related to the TN concentration in the wetlands water body, the landscape index and the TN concentration in the control point water body were analyzed by correlation analysis, step-by-step elimination analysis and path analysis to reveal whether the landscape characteristics are related to the TN concentration under wetlands receiving agricultural drainages. The results showed that the correlation coefficients between four area indexes or eight shape indexes and TN concentration did not reach a significant correlation level(P > 0.05), indicating that TN removal was not only determined by a single landscape index. The path coefficient of edge density(ED) index is –0.41, indicating that wetland patch connectivity is the primary factor of TN removal, and there is no relationship between the larger patch area and the higher TN removal. The removal of TN in wetlands is restricted by the synergistic effect of landscape area and shape characteristics.
