Urban Expansion and Its Influencing Factors in Natural Wetland Distribution Area in Fuzhou City,China

This paper principally focuses on land use dynamics,urban expansion and underlying driving forces in the Natural Wetland Distribution Area(NWDA)of Fuzhou City in the southeastern China.Based on time series Landsat TM/ETM+imageries and historical data,relationships between urban land expansion and its influencing factors from 1989 to 2009 were analyzed by using an integrated approach of remote sensing(RS)and geographic information system(GIS)techniques.The results showed that built-up land increased from 151.16 km2in 1989 to 383.76 km 2in 2009. Approximately 64.25%of the newly emerging built-up land was converted from cropland(29.47%),forest and shrub (25.78%),water(3.73%),wetland(4.61%),and bare land(0.66%)during 1989 and 2009.With a remarkable decrease in cropland,the proportion of non-agricultural population increased by 23.6%.Moreover,rapid development of infrastructures,facilities,industrial parks,and urban and rural settlements along the Minjiang River resulted in the eastward and southward expansion of built-up land.Additionally,the growth pattern of built-up land in the NWDA is highly correlated with socio-economic factors,including the gross domestic product(GDP),GDP per capita,and structure of industry.As a result,the observed environmental degradation such as loss of cropland and wetland due to heavy pressure of rapid urbanization have greatly impaired the carrying capacity of city.Thus,in addition to scientific and rational policies towards minimizing the adverse effects of urbanization,coordination between the administrative agencies should be urgently strengthened to balance the conflicts between urban development and ecological conservation to make sure the sustainable land use.

The current status, threats and protection way of Sanjiang Plain wetland, Northeast China

The Sanjiang Plain is a vast area of alluvial floodplains and low hills in northeast Heilongjiang Province. It is the largest tract of wetlands in China and East Asia outside of Siberia. 28 wetland nature reserves exist on the Sanjiang Plain, and three of them have been listed as wetlands of international importance to water bird conservation by the Ramsar Convention Bureau. The wetlands of Sanjiang Plain are noteworthy for its rich biodiversity, but they continue to decline in area and deteriorate in quality currently. The main threats or constrains, immediate cause, root cause and required response are analyzed in this paper, and the four aspects opinion such as improvement of watershed management, enhancement of protection and restoration of habitats and biodiversity, alternative livelihoods of rural residents living in and near natural wetland reserve, and reinforcement of capacity building of natural reserves are brought forward as the effective measures for the Sanjiang Plain wetland protection.

Economic Value Evaluation of Wetland Service in Yeyahu Wetland Nature Reserve,Beijing

Based on multi-source data,this paper evaluated the economic value of ecological services in the Yeyahu Wetland Nature Reserve,Beijing,China.The ecological services of wetland included gas regulation,water quality im-provement,biodiversity maintenance,erosion control,water supply,recreational opportunity,raw material supply and existence value.Multiple conventional evaluation methods were used to calculate the value of eight wetland services.The results showed that significant values came from biodiversity maintenance and recreational opportunity.The main reasons were as follows.Firstly,Yeyahu Wetland Nature Reserve was the habitat for migrant birds,and government had payed more efforts to protect precious birds.Secondly,the population is large in Beijing.People enjoyed going outside and enjoyed the natural and artificial wetland scenes.At the same time,most people were prepared to pay for wetland conservation.The decline of vegetation cover made the economic value of erosion control the lowest.While the shrink of water resource and the deteriorative water quality caused the economic value of water supply lower.The evaluation results could help decision-makers understand the present status of the Yeyahu Wetland Nature Reserve and provide a scientific basis for strategic decision.

Ecological Environment Status and Protection Measures of Wetland Nature Reserve

In order to better promote the restoration and sustainable development of the natural ecological environment,it is necessary to study the wetland system as an important part of the ecosystem,put forward some common problems faced by wetland nature reserves,and propose relevant solutions based on the problems.This paper describes the relevant theoretical basis for the ecological environment protection of the wetland nature reserves,the problems faced,and the relevant solutions as reference for relevant personnel.

Hengshui Lake China’s Key Wetland Nature Reserve

WETLAND, an important eco-logical sys-tem, is of inestimable scientific, ecological, social and economic value. Bestowed liberally with nature’s bounty, China boasts various types of wetland, and during the past years has built over 130 wetland nature reserves, of which ten percent are

Bird Species Diversity and Spatio-temporal Variation in the Sihong Hongze Lake Wetland National Nature Reserve in Eastern China

As an important hub on the East Asian-Australian Flyway(EAAF),Hongze Lake is an important migratory stopover and wintering site for hundreds of thousands of birds.However,research on bird community diversity in this area is still lacking.We conducted a bird survey from July 2020 to June 2021 using the line transect method on the terrestrial habitat,as well as the fixed-point method in the lake wetland at the Sihong Hongze Lake Wetland National Nature Reserve located in northwestern Hongze Lake,and analyzed the temporal-spatial variation in the bird community.The results showed that a total of 170432 detections of 215 bird species belonging to 18 orders and 55 families were recorded.In terms of species composition,the proportion of terrestrial birds was relatively high,followed by waterfowl richness,with high numbers of Anatidae species and shorebirds.For bird species abundance,waterfowl had the highest abundance of common coot(Fulica atra),belonging to the Rallidae family,followed by Anatidae and Ardeidae species.The abundance of shorebirds was extremely low,and that of non-waterfowl was also low.In terms of temporal patterns,the number of bird species and richness index were higher in spring and autumn but lower in winter and summer.The bird abundance was the highest in winter,and the remaining three seasons were similar in terms of bird abundance.The diversity index and evenness index were higher in spring,summer and autumn,and lowest in winter.For the spatial pattern,the open water in the western part of the reserve included the most densely distributed areas for birds,and the number of bird species and their abundance were both the highest in that part.There were significant differences in the bird community structures among the four habitats.The species number and richness index of birds in the reed habitat were the highest,and the bird abundance was also high,but the diversity index and evenness index were low.Although the bird abundance in the lake habitat was much higher than in the other habitats,the diversity index,evenness index and richness index were the lowest.The numbers of bird species and individuals in tourist attraction land and farmland were low,but the diversity index,evenness index and richness index were high.Our results reveal the spatial and temporal patterns of bird species diversity and abundance in Sihong Hongze Lake Wetland National Nature Reserve,and reflect the effects of different habitat types on bird diversity.

Performance of CH4MOD_(wetland) for the case study of different regions of natural Chinese wetland

Reliable national estimates of CH_4 emissions from natural wetlands depend on model validation based on site observations.We therefore evaluated the performance of the CH_4 MODwetlandmodel in simulating CH_4 emissions from 11 representative wetland sites in five regions of China.Model performance analysis showed that this method effectively simulates differences in the CH_4 fluxes between different sites and regions.The model efficiency for estimating the daily CH_4 fluxes in the northeastern China（NE）,Inner Mongolia and northwestern China（NW）,the North China plain and the Middle-Lower Yangtze Plain（E） and the Qinghai Tibetan Plateau（SW） was 0.51,0.20,0.52 and 0.65,respectively.The efficiency for estimating the annual mean CH_4 fluxes in southern China（S） was 0.99.Systematic negative deviation between the simulated and observed CH_4 emissions existed in all regions,especially in the NW region,which had a mean deviation（RMD） value of-36.7%.On the national scale,the root mean square error（RMSE）,the RMD,the model efficiency（EF）between the simulated and observed seasonal values were 28.7%,-7.8% and 0.93,respectively.The CH_4 emissions showed the highest sensitivity to air temperature in the NE and SW regions,and to water table depth in the E region.Based on the sensitivity analysis,future climate warming and wetting are likely to increase the wetland CH_4 emissions at different levels in all regions of China.

Quantifying of Soil Denitrification Potential in a Wetland Ecosystem, Ochi Experiment Site, Japan

Nitrate contamination has become one of the most important issues for surface water and groundwater. N2O, with an increasing contribution to global warming, has been more and more attention by the IPCC recently. As well known, denitrification plays a major role in nitrogen cycle of aquatic ecosystems and operates at rates far below its potential under proper conditions. Sediments are the single largest pool of nitrogen in wetland ecosystems. During this process, facultative anaerobic bacteria transform nitrite into nitrogen gas which dissolves in the groundwater and diffuses into the atmosphere finally when it shows up with seepage or spring in the wetland. To seek a mechanistic understanding of N removal in natural wetland ecosystem, a case study was carried in terms of denitrification rate at the Ochi catchment, Chiba, Japan. In this study, samples of intact soil cores in 0–20cm were taken along the groundwater flow path, which including 2 samples in the unsaturated zone and 2 in saturated wetland ecosystem. Denitrification capacity of soil was quantified using acetylene （C2H2） inhibition/gas chromatography ECD method with time intervals of 0, 2, 6, 12, 24 h. Total-N and Total-C contents and amount of denitrifying bacteria were also analyzed. It is found that denitrification ability is low for all 2 samples in the unsaturated zone and high in saturated zone. Results show that N2O emission flux after C2H2-inhibition ranges from 0 to 1.17 gN m^-2h^-1, with an increase value prior 6 hours and slow down after that.

Coastal wetland vegetation features and digital Change Detection Mapping based on remotely sensed imagery:El-Burullus Lake, Egypt

El-Burullus Lake is one of the four Egyptian Ramsar sites that constitute internationally important wetlands as they contain a rich biodiversity and have a large number of water bird species.But the valuable resources in El-Burullus Lake and its surrounding area have faced various threats to wetlands over recent decades.This study was carried out to evaluate the dynamics of land cover change using three change scenes of recent and past satellite data from 1990 to 2019.The study utilized ArcGIS10.7,ERDAS Imagine 14,Landsat TM(1990,1999,and 2010),Landsat OLI-TIRS(2019)to analyze the land-use/land-cover(LULC)of El-Burullus wetland.Normalized Difference Vegetation Index(NDVI)and Normal-ized Difference Water Index(NDWI)were employed to assess the change scenario of the area.Results indicated that vegetated land has increased significantly with a concomitant shrinkage in the water body and open soil during the study period.Approximately 53 km^2(7.0%)of water body and 8.7 km^2(1.3%)of open soil were lost,while vegetation areas expanded to approximately 29.9 km^2(7.4%).Factors that underpin the observed changes in the area are;reclamation projects and fish-farms which are creating the danger of drying up of the southern coastal parts of the lake,as well as spreading of reed beds(mainly:Phragmites australis)that covers about 20%of El-Burullus lake which led to dry up the lake parts.Therefore,the study suggests the need for urgent attention on conservation of remaining wetland resources for sustainable utilization for the next generation.

Evaluation of Ecosystem Services Value of the Zoigê Wetland Nature Reserve by Multiple Criteria

Understanding the value of ecosystem services is useful for the decision making and sustainable management of the wetlands. It would be better to integrate ecological, economic and social factors into ecosystem service valuation. The general value of the Zoigê Wetland Nature Reserve in the southwest China by integrating a social welfare weight, which is determined by a three-level analytic hierarchy process, was calculated. Through analyzing the functions, stakeholders and ecosystem services of the Zoigê Wetland Nature Reserve, the six main services, including substance production, flood control, gas regulation, climate regulation, recreation, and biodiversity conservation,were selected; and a three-level hierarchical structure model was established. The top(goal) level of the model refers to the total ecosystem services value of the Zoigê Wetland Nature Reserve, the middle level(stakeholder level) refers to stakeholders at different scales, and the bottom level(service level) refers to individual services provided by the Zoigê Wetland Nature Reserve. The results indicated that the ecosystem services value of the Zoigê Wetland Nature Reserve was 320.38×10~8yuan RMB in 2011. If including the social welfare, the value increased to 2258.68×10~8yuan RMB. The value of biodiversity conservation accounted for the largest proportion, which were 53% without the social welfare and 75% with it. And without the social welfare, flood control, gas regulation, climate regulation of the Zoigê Wetland Nature Reserve accounted for 26%, 11% and 8% of the total value, while the proportion that substance production and recreation values were of the total value were very small. Meanwhile, with the social weight,flood control, gas regulation, climate regulation, recreation of the Zoigê Wetland Nature Reserve accounted for 10%,13%, 1% and 1% of the total value, then the weight of substance production value was also the smallest.

Dissolved nitrous oxide and emission relating to denitrification across the Poyang Lake aquatic continuum

Most aquatic ecosystems contribute elevated N2 O to atmosphere due to increasing anthropogenic nitrogen loading. To further understand the spatial heterogeneity along an aquatic continuum from the upriver to wetland to lake to downriver, the study was conducted on spatial variations in N2 O emission along Poyang Lake aquatic continuum during the flood season from 15 July 2013 to 10 August 2013. The results showed the N2 O concentrations, the ratio of N2O/dinitrogen（N2） gases production, N2 O emission and denitrification rates ranged from 0.10 to 1.11 μg N/L,- 0.007% to 0.051%,- 9.73 to 127 μg N/m2/hr and 1.33 × 104to31.9 × 104μg N2/m2/hr, respectively, across the continuum. The average N2 O concentrations,the ratio of N2O/N2 and N2O emission was significantly lower in wetlands as compared to the rivers and lake（p 〈 0.01）. The significantly high denitrification rate and low N2 O emission together highlighted that most N2 O can be converted into N2 via near complete denitrification in the Poyang Lake wetlands. Our study suggests that the wetlands might impact N2 O budget in an integrated aquatic ecosystems. Moreover, N2 O emission from different aquatic ecosystem should be considered separately when quantifying the regional budget in aquatic ecosystem.