Mapping of Freshwater Lake Wetlands Using Object-Relations and Rule-based Inference

Inland freshwater lake wetlands play an important role in regional ecological balance. Hongze Lake is the fourth biggest freshwater lake in China. In the past three decades, there has been significant loss of freshwater wet- lands within the lake and at the mouths of neighboring rivers, due to disturbance, primarily from human activities. The main purpose of this paper was to explore a practical technology for differentiating wetlands effectively from upland types in close proximity to them. In the paper, an integrated method, which combined per-pixel and per-field classifi- cation, was used for mapping wetlands of Hongze Lake and their neighboring upland types. Firstly, Landsat ETM＋ imagery was segmented and classified by using spectral and textural features. Secondly, ETM＋ spectral bands, textural features derived from ETM＋ Pan imagery, relative relations between neighboring classes, shape fea^xes, and elevation were used in a decision tree classification. Thirdly, per-pixel classification results from the decision tree classifier were improved by using classification results from object-oriented classification as a context. The results show that the technology has not only overcome the salt-and-pepper effect commonly observed in the past studies, but also has im- proved the accuracy of identification by nearly 5%.

Valuation of Lake and Marsh Wetlands Ecosystem Services in China

Wetlands are highly productive natural ecosystems, providing valuable goods and services. There is growing interest in transferring ecosystem service value from the existing wetlands studied to other wetlands ecosystems at a large geographic scale. The benefit transfer method uses the known values from wetlands to predict the value of other wetland sites. This methodology requires only limited time and resources. The present study calculated the value of the ecological services provided by lake and marsh wetlands in China in terms of biodiversity indices, water quality indices and economic indices. Basic data on wetlands were obtained through remote sensing images. The results show that: 1) The total ecosystem service value of the lake and marsh wetlands in 2008 was calculated to be 8.1841 × 1010 United States Dollars(USD), with the marsh and lake wetlands contributing 5.6329 × 1010 and 2.5512 × 1010 USD, respectively. Values of marsh ecosystem service were concentrated in Heilongjiang Province(2.5516 × 1010 USD), Qinghai Province(1.2014 × 1010 USD), and Inner Mongolia Autonomous Region(1.1884 × 1010 USD). The value of the lakes were concentrated in Tibet Autonomous Region(6.223 × 109 USD), Heilongjiang(5.810 × 109 USD), and Qinghai(5.500 × 109 USD). 2) Waste treatment and climate regulation services contributed to 26.29% and 24.74% respectively, of the total ecosystem service value of the marsh wetlands. Hydrological regulation and waste treatment contributed to 41.39% and 32.75%, respectively, of the total ecosystem service value of the lake wetlands. 3) The total ecological service value of the lake and marsh wetlands was 54.64% of the total service value of natural grassland ecosystems and 30.34% of the total service value of forests ecosystems in China.

A Comparison of Habitat Use by Wintering Bean Goose and Common Crane in Yeya Lake Wetlands

Identifying the habitat use in relation with time between 2 bird species in a wetland can help our understanding of how wintering bird species interact and coexist in the same system.The detection probabilities of Bean Goose(Anser fabalis)and Common Crane(Grus grus)were investigated in Yeyahu Wetland Nature Reserve in Beijing over a whole wintering season.Moreover,how use proportion of each type of habitats varied with time for 2 bird species was explored.In the detection probability study,the method of fixed-radius point was used to observe and infer the presence of species.An occupancy model was applied to deal with the occupancy of a sampling unit,accounting for imperfect detection.In the survey for habitat use,the types of habitats that 2 bird species were occupying were investigated by a line-transect method.Then,the method of multinomial logistic regression was applied to compare the proportions that various types of habitats were used during the days after 2 bird species arrived.The parameters of the detection probability model and multinomial logistic regression equation in a Bayesian framework using Markov Chain Monte Carlo(MCMC)simulations were estimated.The detection probability model was used to predict that Bean Goose arrived in Yeya Lake Wetlands in the middle of October and left at the end of March next year,whereas Common Crane arrived at the end of October and left in the middle of April next year,with almost 5 months coexisting in Yeya Lake Wetlands.The result of the multinomial logistic regression showed Bean Goose gradually decreased use proportion of the water but increased use proportion of grassland over time,and use proportion of farmland remained constant at the beginning but declined later.Common Crane decreased use proportions of the water and grassland but increased that of farmland over time.Common Cranes were more competitive for farmland habitat.It was implied that Bean Goose and Common Crane adjusted and segregated the use proportion of grassland and farmland during their wintering period,which might mitigate interspecific competition and allow for coexistence.It was suggested that adequate habitats of grassland and farmland were probably important requirement enabling habitat segregation and coexistence of Bean Goose and Common Crane and that the overall habitat quality of a wintering site was likely to incorporate the availability of these resources,which provided multiple fitness advantages through secured food supplies and reduced predation risk.Thus,habitats providing adequate food supplies and protection might be unsuitable wintering habitats given an improper agricultural landscape management.Finally,it was proposed that maintenance of habitat diversity and improved farming methods,such as stoping crop residue burning and delaying the time of plowing,could be incorporated in agricultural landscape management plans on habitats of Bean Goose and Common Crane.

Study on Qianling Lake Restoration with Artificial Wetland

The ecological restoration of water quality in Qianling Lake was conducted by artificial wetland, which transformed N and P in wastewater into essential matters in organism tissues, so pollutants discharged into Qianting Lake were reduced for the purpose of restoration.

Evaluation on Non-use Value of Dianchi Lake Wetland Using CVM

[Objective] This study was to analyze the personal Willingness to Pay （WI-P） on the non-use value of Dianchi lake wetland and the influential factors. [Method] Questionnaire was designed according to the Contingent Valuation Method （CVM） to investigate people of different occupations at different ages, based on which the evaluation on non-use value of Dianchi lake wetland was carried out. And the relationship between WTP and social characteristics were analyzed by using non- parametric estimation. [Result] The average WTP on Dianchi lake wetland is 150.03- 217.66 yuan per person every year, and the total WTP is 626-909 million yuan ev- ery year. Age, education and residence of the respondents have remarkable influ- ence on the VVTP. The influence of education level and residence on option value is significant; bequest value is significantly correlated with age; while there is no significant relationship between existence value and social characteristics. [Conclusion] The evaluation on the non-use value of Dianchi lake wetland is important for the scientific development and utilization of wetland resources.

Effects of Water-table Depth and Soil Moisture on Plant Biomass, Diversity, and Distribution at a Seasonally Flooded Wetland of Poyang Lake, China

Hydrological regime has been widely recognized as one of the major forces determining vegetation distribution in seasonally flooded wetland. Poyang Lake, the largest freshwater lake in China, has been encountering dramatic changes in hydrological conditions in last decade, which greatly influenced the wetland vegetations. To explore the relationships between hydrology and vegetation distri- bution, water-table depth, soil moisture, species composition, diversity and biomass were measured at a seasonally flooded wetland section at Wucheng National Nature Reserve. Three plant communities, Artemisia capillaris, Phragmites australis and Carex cineras- cens communities, were examined which are zonally distributed from upland to lakeshore with decreasing elevation. Canonical corre- spondence analysis （CCA）, spearmen correlation and logistic regression were adopted to analyze the relationships between vegetation characteristics and hydrological variables of water-table depth and soil moisture. Results show that significant hydrological gradient exist along the wetland transect. Water-table demonstrates a seasonal variation and is consistently deepest in A. capillaris community （ranging from q）.5 m above ground to ＋10.3 m below ground）, intermediate in P. australis community （-2.6 m to ＋7.8 m） and shallow- est in C. cinerascens community （-4.5 m to ＋6.1 m）. Soil moisture is lowest and most variable in A. capillaris community, highest and least variable in P. australis community, and intermediate and moderate variable in C. cinerascens community. The CCA ordination indicated that variables of water-table depth and soil moisture are strongly related to community distribution, which explained 81.7% of the vegetation variations. Species diversity indices are significantly positively correlated with soil moisture and negatively correlated with moisture variability, while above- and belowground biomass are positively correlated with moisture. Above- and belowground biomass present Gaussian models along the gradient of average water-table depth in growing season, while species diversity indices show bimodal patterns. The optimal average water-table depths for above- and belowground biomass are 0.8 m and 0.5 m, respectively, and are 2.2 m and 2.4 m for species richness and Shannon-Wiener indices, respectively. Outcomes of this work improved the under- standings of the relationship between hydrology and vegetation.

Shrinking and Drying up of Baiyangdian Lake Wetland:A Natural or Human Cause?

The shrinking and drying up of wetlands in arid and semiarid areas of China have been widely observed in the recent years, but there has been no consensus on whether the aggravation is caused by human activities or by global climate warming. For a better understanding of the cause, this study investigates the dynamic changes of Baiyangdian Lake wetland over the last 40 years. It is shown that since the 1980s, Baiyangdian Lake has suffered from an insufficient water input and shrunk considerably. By using SPSS 11.0, this study urines a detailed Analysis on the signifficance of the effects of the possible driving factors for the degradation. It is identified that the North China Plain has been warrnin~ up significantly in recent years, which causes a significant reduction in the precipitation and inflow to the lake. Although human disturbances such as the irrigation and storage of water in reservoirs do not play a decisive role, they accelerate the degradation and their effects should be minimized.

Population sizes and group characteristics of Siberian Crane(Leucogeranus leucogeranus) and Hooded Crane(Grus monacha) in Poyang Lake Wetland

Both the Siberian Crane(Leucogeranus leucogeranus) and Hooded Crane(Grus monacha) have limited population sizes and are considered endangered by domestic Chinese and international agencies.To document the current size of their respective populations and characterize their groups,between October 2012 and April 2013 we undertook fieldwork at four nature reserve areas within the Poyang Lake wetlands.We divided Poyanghu National Nature Reserve(PYH) into the Wucheng(PWC) and Hengfeng areas(PHF),because each are each located in different counties.Our fieldwork showed that the Siberian Crane occurred mainly in PYH(364 in the PHF,158 in the PWC) and the Nanjishan Wetland National Nature Reserve(NJS,with 200 individuals).The Hooded Crane was mainly distributed in PYH(302 in the PHF and 154 in the PWC).Family groups accounted for more than 50% of the total number of groups among both species,with Hooded Cranes forming more family groups than Siberian Cranes.Typically,these groups were formed of two adults with one offspring(Siberian Crane),and two adults with two offspring(Hooded Crane),with the mean family group size of the Siberian Crane and Hooded Crane being respectively 2.65±0.53(n=43) and 3.09±0.86(n=47) individuals per group.The mean collective group size of the Siberian Crane and Hooded Crane included 28.09±24.94(n=23) and 28.94±27.97(n=16) individuals per group,respectively,with the proportion of juveniles among Hooded Cranes being more than double that seen among the Siberian Cranes.

Shifts of sediment bacterial community and respiration along a successional gradient in a typical karst plateau lake wetland(China)

Bacteria are important regulators of carbon cycling in lakes and are central to sediment ecosystem processes.However,the sediment microbial communities and their respiratory responses to the lake wetland succession are poorly understood.In this study,we collected sediment samples from four different succession points(the Potamogeton lucens zone,the Scirpus tabernaemontani zone,the Scirpus triqueter zone,and the Juncus effusus zone)in the Caohai Wetland of the Guizhou Plateau(China).The bacterial communities at these succession points were studied using a high-throughput sequencing approach.The sediment microbial respiration(SR)was measured using static chambers in the field and basal respiration(BR)was determined in the laboratory.The results show that the dominant bacterial taxa in the sediment was Proteobacteria(34.7%),Chloroflexi(17.8%),Bacteroidetes(7.3%),Acidobacteria(6.6%),and Cyanobacteria(6.1%).Principal coordinate analysis showed that the microbial community structure differs significantly at different sampling points along the successional gradient,indicating that the bacterial community structure is sensitive to the lake wetland succession.Different hydrological regimes and soil characteristics such as NH_(4)^(+)-N,Fe^(2+),Mn^(2+),and sediment organic carbon(SOC)content may be important factors responsible for the differences in the sediment microbial characteristics of the different successional stages in the Caohai wetland.Additionally,it was found that the SR increased significantly from the P.lucens zone to the J.effusus zone,but BR had the opposite response.The shifts in the bacterial community structure along the successional gradient may be the main reason for the observed differences in sediment respiration.

Phylogenetic and Molecular Analysis of an H7N7 Avian Influenza Virus Isolated in East Dongting Lake in 2012

Objective In March 2012, an H7N7 subtype avian influenza virus （AIV） named A/wild goose/Dongting/PC0360/2022 （H7N7） （DT/PC0360） was recovered from a wild goose in East Dongting Lake. We performed whole-genome sequencing of the isolate, and analyzed the phylogenetic and molecular characterization. Methods RNA was extracted from environment samples （including fecal samples from wild bird or domestic ducks, and water samples） for detecting the presence of Influenza A Virus targeting Matrix gene, using realtime RT-PCR assay. The positive samples were performed virus isolation with embryonated eggs. The subtype of the isolates were identified by RT-PCR assay with the HI-HI6 and N1-N9 primer set. The whole-genome sequencing of isolates were performed. Phylogenetic and molecular characterizations of the eight genes of the isolates were analyzed. Results Our results suggested that all the eight gene segments of DT/PC0360 belonged to the Eurasian gene pool, and the HA gene were belonged to distinct sublineage with H7N9 AIV which caused outbreaks in China's Mainland in 2013. The hemagglutinin cleavage site of HA of DT/PC0360 showed characterization of low pathogenic avian influenza virus. Conclusion Strengthening the surveillance of AlVs of wild waterfowl and poultry in this region is vita for our knowledge of the ecology and mechanism of transmission to prevent an influenza pandemic.

Characteristics of the Distribution of Plant Community in Lakeshore Wetland of Yunnan Plateau

[ Objective] The aim was to discuss the distribution of plant community in lakeshore wetland of Yunnan Plateau. [ Method ] Taking sever- al lakes in Yunnan Plateau as example, the distribution characteristics and rules of plant community in lakeshore wetland of Yunnan Plateau were discussed. The degradation and causes of lakeshore wetland were analyzed. [ Resultl The wetland plants were characterized by reduction of the aquatic plant species, the decline of the species diversity and the biomass. Fast breeding vegetation with high fat and pollution tolerance, strong adaptability was easy to form a single optimal community. Some representative and sensitive to pollution plants deteriorated or destroyed. These phenomena reflected the changes of water quality, the worse pollution, eutrophication and the acceleration of turning wetland to land. The causes of wetland degradation and biodiversity included increase of population pressure, industrial and agricultural development, advance of urbanization, unreasonable cultivation, over-exploitation and eutrophication, etc. [ Conclusion] The study provided theoretical basis for the protection, environ- ment evaluation and sustainable development of lakeshore wetland.

Characteristics of Photosynthetic Fluorescence of Dominant Submerged Plants in Nanjishan Wetland of Poyang Lake in Winter

Based on the investigation of the species and frequency of submerged plants in Nanjishan Wetland of Poyang Lake in the winter of 2013,chlorophyll contents and photosynthetic fluorescence characteristics of the dominant submerged plants were studied using chlorophyll fluorescence imaging method. The results indicate that the major submerged plants of Nanjishan Wetland in Poyang Lake in winter included Hydrilla verticillata,Vallisneria natans,Najas minor,Potamogeton pectinatus,Nymphoides peltatum,Myriophyllum verticillatum and so on,and the dominant species were mainly H. verticillata and V. natans in different submerged plant communities. The chlorophyll content of H. verticillata is higher than that of V.natans,and the photosynthesis intensity of H. verticillata is stronger than that of V. natans. The value of Ca / Cb of H. verticillata is not large,which shows that the light-harvesting capacity of H. verticillata＇s chlorophyll is considerable in different sampling sites. The highest value of QY-max of V.natans is up to 0. 732,while the lowest value is only 0. 465; the highest value of QY-max of H. verticillata is 0. 677,while the lowest value is 0. 556.All values of QY-max of the submerged plants were lower than 0. 8,which shows that the submerged plants in Nanjishan Wetland of Poyang Lake may be subjected to certain external stress,which indicates that the external stress might cause some damage for the PSII reaction centers.

Sandy Land-lake-vegetation Landscape of Songnen Sandy Land of China:Pattern,Process and Mechanism

In order to investigate the dynamic evolution of the sandy land-lake-vegetation landscape in Songnen Sandy Land(SSL)and its response to climate change and human activities,the distribution pattern,evolution,and driving mechanisms of the landscape were analyzed based on Landsat satellite images and meteorological and socio-economic data during 1980–2020.The results indicate that the area of sandy land exhibited an upward fluctuation during the last 40 yr,with a net increase of 251.75 km^(2) at an increment rate of 3.80%/10 yr.The lake area also exhibited an upward fluctuation,with a net increase of 1200.95 km^(2) at an increment rate of 20.42%/10 yr.Vegetation coverage decreased by 2633.30 km^(2),with areas of low vegetation coverage exhibiting a trend of initial decline and subsequent increase,areas of medium vegetation coverage showed an upward fluctuation,and areas of high vegetation coverage showed a trend of initial increase and subsequent decrease,with overall changes of–0.67%/yr,1.12%/yr,and 0.17%/yr,respectively.The relationships between sandy land,lakes,and vegetation coverage were significant,with areas of sandy land and low vegetation coverage showing the strongest correlation.The dynamic evolution of landscape is controlled by regional climatic and socio-economic factors,with socio-economic factors as the first principal component contributing up to 59.64%.

Value Assessment of the Lake Hpnghu Wetland and Protection of Its Biodiversity

A wetland ecosystem's value may be considered as the value derived from its natural resources, the value derived from its eco-environment, the value for special protection and values in cultural, research and educational aspects. Lake Honghu, in the heartland of Hubei Province, covers a vast but shallow body of water and surrounding marshlands. It is conducive to farmland irrigation, flooding regulation, adjustment of the local climate and self-purification of the water quality. Because of its benign functions, the native ecosystem of the lake is ecologically sound, and the thriving wildlife in its ecosystem makes it a primordial pool of biodiversity. Besides, it is possible to transform it into a national base for environmental education and an R&D center for freshwater organisms, so that it can play a constructive role in heightening the public's awareness of environmental protection.

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.

Cyperus papyrus L. Growth Rate and Mortality in Relation to Water Quantity, Quality and Soil Characteristics in Nyando Floodplain Wetland, Kenya

Cyperus papyrus (L.) growth rate and mortality is influenced by environmental conditions prevailing in the wetland. To assess growth dynamics of C. papyrus in relation to water depth and anthropogenic (exploitation) pressures, monthly and bi-monthly measurement of culm length and girth were done between June and December 2010 (period 1) and April to June 2011 (period 2). Three study sites were selected based on the water levels and livelihood-driven exploitation pressures. Surrogate measurements of individual culm height and girth were done in three 1 m2 quadrats in each site to determine the growth rate of papyrus. Water depth was lowest in period 2 (dry) and highest in period 1 (wet) which was related to the livelihood activities being highest in period two and lowest in period one. Culm mortality occurred throughout the study period with 64% due to natural senescing while insect/rodent accounted for 19%. Papyrus growth was higher in Singida (2.5 ± 0.2 cm/day) representing less disturbed site and least in Wasare (1.4 ± 0.1 cm/day) which was highly disturbed. Multiple regression models for culm length showed culm density, mean length and NH4 negatively influenced growth rate while site as a dummy variable, water depth, SRP and TP had positive effects on papyrus growth rate. Understanding growth rate and causes of mortality in papyrus is important to establish sustainable management strategies of this ecosystem to maintain its integrity.

Automated and refined wetland mapping of Dongting Lake using migrated training samples based on temporally dense Sentinel 1/2 imagery

Wetlands provide vital ecological services for both humans and environment,necessitating continuous,refined and up-to-date mapping of wetlands for conservation and management.in this study,we developed an automated and refined wetland mapping framework integrating training sample migration method,supervised machine learning and knowledge-driven rules using Google Earth Engine(GEE)platform and open-source geospatial tools.We applied the framework to temporally dense Sentinel-1/2 imagery to produce annual refined wetland maps of the Dongting Lake Wetland(DLW)during 2015-2021.First,the continuous change detection(CCD)algorithm was utilized to migrate stable training samples.Then,annual 10 m preliminary land cover maps with 9 classes were produced using random forest algorithm and migrated samples.Ultimately,annual 10 m refined wetland maps were generated based on preliminary land cover maps via knowledge-driven rules from geometric features and available water-related inventories,with Overall Accuracy(OA)ranging from 81.82%(2015)to 93.84%(2020)and Kappa Coefficient(KC)between 0.73(2015)and 0.91(2020),demonstrating satisfactory performance and substantial potential for accurate,timely and type-refined wetland mapping.Our methodological framework allows rapid and accurate monitoring of wetland dynamics and could provide valuable information and methodological support for monitoring,conservation and sustainable development of wetland ecosystem.