Dynamics of Wetland Landscape Pattern in Kaifeng City from 1987 to 2002

It is very significant for urban development and urban wetland protection and utilization to probe into the process and reasons of urban wetland landscape dynamics. Taking the information of remote sensing and detailed land survey data as the basic information sources, with the help of RS and GIS, according to the principles and methods of landscape ecology, this paper analyzed wetland landscape pattern dynamics and its reasons in Kaifeng City, Henan Province of China, from 1987 to 2002. The results show that the total wetland area in Kaifeng City firstly reduced by 20.1% from 1987 to 1990 and then increased from 1990 to 2002, with an average annual growth rate of 3.3%. At the same time, landscape fragment degree and landscape dominance degree increased, respectively from 0.64 to 0.72 and from 0.3754 to 0.5563, but mean patch area, maximum patch area, patch fractal dimension reduced. As far as single landscape element concerned, fi＇om 1987 to 2002, patch area, patch number, patch density, patch shape and patch location changed in varying degrees in all wetland types in Kaifeng City, among which rice field changed most and others relatively less. In the recent 20 years, rice fields, lake wetlands, puddles and ponds had a higher stability, but river and bottomland wetlands were mostly transformed to land use types. The change of wetland landscape pattern was the result of the combined action of the Huanghe （Yellow） River, urban expansion, wide cultivation of rice, and rapid development of fishery. Among them human activities were the main driving factors for wetland landscape changes.

Landscape pattern dynamics of water body in Kaifeng city in the 20th century

Landscape spatial pattern mainly refers to the distribution of patches, which are different in size and shape in space owing to the interaction of various ecological activities. In landscape ecology study, landscape pattern has been one of the key study areas. Water body landscape plays an important role in the development history of a city, but at present city water body landscape in many cities has been destroyed, hence protecting water body in the city is becoming more and more important. In order to protect city water body landscape reasonably, the precondition is to probe the dynamics of water body landscape. Based on historical data and remote sensing data, six indexes including patch number, patch area, landscape dominance index, fractal dimension, patch density and connectivity index etc. were used to analyze landscape pattern dynamics of water body in Kaifeng city since the end of the Qing Dynasty (in the 20th century). The results showed: (1) Since the end of the Qing Dynasty, landscape area of water body in Kaifeng city increased first and then decreased from 1898 to 2002AD; the landscape dominant degree had the same changing tendency with the area. (2) Patch number of water body landscape in Kaifeng city had an increase from 1898 to 2002, but maximum area of patch, minimum area of patch and average area of patch decreased, which resulted in an increase in landscape fragment degree. (3) Connectivity index decreased and fractal dimension increased from 1898 to 2002. The reasons for these changes were the repeated overflows and flooding of the Yellow River and the influence of human activities.

The distribution and ecological risks of antibiotics in surface water in key cities along the lower reaches of the Yellow River:A case study of Kaifeng City,China

A large number of antibiotics have been discharged into rivers by human activities,posing a threat to aquatic ecosystems.The surface water of the Yellow River Basin also suffers antibiotic pollution,which hinders the improvement in the aquatic ecological environment.This study investigated and analyzed the characteristics and assessed the ecological risks of antibiotic pollution in surface water bodies such as canals,rivers and fish ponds in Kaifeng,Henan Province,which is a key city along the lower reaches of the Yellow River.The test results are as follows.A total of 15 types of antibiotics were detected in the surface water.They had a total antibiotic concentration of 12.2-249.9μg/L,of which tetracyclines(TCs)and quinolones accounted for the highest percentages.Six types of quinolones had detection rates of up to 100%,and doxycycline(DC)and oxytetracycline(OTC)had average concentrations of 29.52μg/L1 and 13.71μg/L,respectively.The major canals with water diverted from the Yellow River had total concentrations of quinolones and TCs of 22.0μg/L and 14.9μg/L,respectively,which were higher than those in previous studies.This phenomenon may be related to the decrease in the water flow of the Yellow River during the dry season and the increase in the antibiotic consumption of residents in the context of the Covid-19 outbreak.The upper reaches of the Huiji River in the Xiangfu District had higher antibiotic content than other districts in Kaifeng.Specifically,TCs accounted for 72.38%-91.84%of all antibiotics,and the DC and OTC concentrations were significantly higher than other antibiotics in the upper reaches.As indicated by the ecological risk assessment results,TCs had the highest ecological risks to green algae.Among them,DC had medium-high risks;TC,OTC,and chlortetracycline(CTC)had medium-high risks;trimethoprim(TMP)and lomefloxacin(LOM)had low risks;other TC antibiotics had no risk.Compared with green algae,most antibiotics showed higher ecological risks to daphnia and lower ecological risks to fish.DC and OTC dominate antibiotic pollutants in the surface water in Kaifeng City,and especially in Xiangfu District,where DC and OTC have medium-high risks.The TCs in the major Yellow River showed medium risks to both green algae and daphnia.It can be speculated that the antibiotic pollution in the Yellow River might pose a certain threat to the ecological security of water in Kaifeng City.

Urban niche dynamics of Kaifeng city

Niche theory is one of the most important ecological theories. It is widely applied to analyzing such phenomena as competition among, and evolution of, urban ecosystem functional modules. This paper describes a study concerning＇different functional modules of Kaifeng city urban ecosystem. Niche theory and techniques were used to analyze the changes of these functional modules in the period 1994-2003. The results showed that, in the period 1994-2003： （1） Niche value of the atmospheric environment and urban virescence modules increased, while niche value of the water environment and sound environment modules decreased; （2） niche value of the tertiary industry module increased, niche value of the secondary industry module decreased, while niche value of the primary industry module showed little change; and （3） niche value of the infrastructure, resource distribution, and production ＆ social security modules increased, while niche value of the population module decreased. This study may contribute to macroscopic planning of urban functional modules, economic development, and environmental protection.

Evaluation and Obstacle Diagnosis of Low-carbon Intensive Land Use in Kaifeng City

Low carbon intensive use of urban land is an important trend to achieve regional high quality development.In this study,with Kaifeng municipal district as an example,the catastrophe progression model was used to estimate and analyze the low-carbon intensive use level of urban land in Kaifeng City from 2011 to 2020,and the obstacle factors in the process of low-carbon intensive land use in Kaifeng City were revealed by using the obstacle degree model.The results showed that during the study period,the low-carbon intensive use of land in Kaifeng City showed a slow,fluctuating and declining trend,and the overall situation was in a generally intensive state.The land input level and land output level were on the rise,while the low-carbon level of land and the degree of land use were on the decline.Currently,the main obstacle factors restricting the low-carbon intensive use of land in Kaifeng City were the carbon structure coefficient of land use,energy consumption per square kilometer,carbon emissions per square kilometer,carbon emissions per capita,and non-agricultural land use efficiency.In the future,it is necessary to further improve the land use structure and promote the high-quality development of Kaifeng City.

Content and densities of soil organic carbon in urban soil in different function districts of Kaifeng

Urban soil, forming along with the development of city, has unique properties of soil organic carbon. On the basis of field investigation and laboratory analysis, soil organic carbon （SOC） of Kaifeng city was studied, and the results showed that the characteristics of SOC were different not only among function districts in urban area, but also between urban area and suburbs. The order of SOC in topsoil was industrial district 〉 recreational district 〉 traffic district 〉 cultural/educational district 〉 residential/administrative district. The density of soil organic carbon （SOCD） in both topsoil and profile followed the orders of recreational district 〉 industrial district 〉 traffic district〉cultural/educational district 〉 residential/adminis-trative district, and cultural/educational district 〉 traffic district〉industrial district〉recreational district 〉 administrative/residential district, respectively. SOCD in both topsoil and profile decreased along the transection line from urban area to suburbs and urban area had 2.53-fold more SOCD in topsoil and 1.56-fold more SOCD in profile than suburbs, respectively. SOC decreased with the depth and was mainly distributed within the scope of 0-30 cm. The variances of SOC in urban area were more complicated than that in suburbs.

Comprehensive Management and Protection of Lakes in Kaifeng

Through analysing pollution source and status quo of the main lakes in Kaifeng,such as Dragon Pavilion Lake and Baogong Lake,the conclusion is that Kaifeng＇s lake environment has been in a greater pollution condition. For lake pollution situation,we put forward comprehensive management and protection approaches of lakes,including the relocation of businesses around the lake,plugging the sewage outfall surrounding lakes,dredging and deeply digging to increase the water environment capacity of lake. By dredging the river,the lakes in urban district connect together. Controlling aquaculture scale of lakes,the ecological function of the lake is played. Constructing drainage network around the lake,integration of landscape and lake flood control is formed. Adding new water into lakes,stagnant water becomes flowing water. We sum up the experience of lake management and protection： strengthening protection awareness is the key; lake remediation is the fundamental; attention to ecological protection of the lake is the most important factor in the development of lakes; exploiting a variety of functions of the lakes including landscaping,tourism,recreation,aquaculture,public health is the goal.