Table of Content

    25 May 2023, Volume 2023 Issue 3 Previous Issue   
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    Ecological and Environmental Sciences
    A scheme of vegetation classification system at city scale and its application in Shanghai
    Liangjun DA, Zhiwen GAO, Yongchuan YANG, Kun SONG, Xueyan GUO, Hong LIANG, Tiyuan XIA, Huafeng WANG, Ting ZHOU, Daigui ZHANG, Zhihui TIAN, Yuandong HU, Bo JIA
    2023, 2023 (3):  1-8.  doi: 10.3969/j.issn.1000-5641.2023.03.001
    Abstract ( 341 )   HTML ( 241 )   PDF (574KB) ( 311 )   Save

    The development of city-scale vegetation maps is helpful for vegetation management and conservation. Vegetation classification systems in China mainly consider natural vegetation and most classification systems operate at the national or provincial scale, making them unsuitable for city-scale classification. Until now, the lack of a classification system designed specifically for urban vegetation has limited the studies on urban vegetation. Based on the origin, disturbance, and function, our classification system divides urban vegetation into natural, secondary, and cultivated vegetations. Based on the function, cultivated vegetation is further divided into artificial forest land, landscape green land , and urban agricultural vegetations. Based on the Classification System of China’s Vegetation in 1980 and the three newly proposed preliminary guideline documents for classification of natural vegetation, we establish a new urban vegetation classification system. We applied the principles of this new urban system in Shanghai and other areas in China, to further refine the system and ensure it has both academic and practical values. This work provides the theoretical basis for compiling information about urban vegetation and provides technical support for the recognition, protection, construction, and management of urban vegetation.

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    Diversity of plants in Chinese Taoist temples and the distribution pattern of Taoist tree species
    Wei CHANG, Yongchuan YANG, Cheng JIN, Xinyang WANG, Li HUANG, Lihua ZHOU, Siwei HU
    2023, 2023 (3):  9-19.  doi: 10.3969/j.issn.1000-5641.2023.03.002
    Abstract ( 446 )   HTML ( 247 )   PDF (1768KB) ( 180 )   Save

    In this study, we obtained tree species from 72 Taoist temples across China. We subsequently documented the tree species composition, distribution pattern, and impact factors in different regions to determine the role of Taoist temples in biodiversity protection. The results showed that: ① Among 72 Taoist temples sampled across China, we observed a total of 354 species of trees, belonging to 85 families and 208 genera; ② The tree species in the Taoist temples were mainly native species, and the mean value for the proportion of native species in each Taoist temple was 62.5%±19.8% (mean ± standard deviation). Most of the Taoist temples (77.8%), moreover, housed threatened tree species; ③ Taoist tree species originated largely from subtropical regions, with the Yangtze River Basin being the most represented, especially in the southwest and south-central regions where a relatively large proportion of ethnic minorities reside; ④ The main factors affecting the distribution of Taoist tree species were geography and climate, but their composition was indistinguishable within each climate zone. As the climatic zone moves northward, there is no religious tree species replacement phenomenon (i.e., replacing the original religious tree species by native tree species with similar morphology or cultural meaning). The above results indicate that Taoist temples are rich in plant resources, which are potential biodiversity treasures. Thus, they play an essential role in protecting and maintaining biodiversity, with the potential to serve as a reference for regional ecological restoration and urban green space construction.

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    Diversity pattern and driving factors for soil microbes in a peri-urban area
    Yan GAO, Rong WANG
    2023, 2023 (3):  20-32.  doi: 10.3969/j.issn.1000-5641.2023.03.003
    Abstract ( 173 )   HTML ( 227 )   PDF (2056KB) ( 68 )   Save

    We collected soil samples from Maogang Town (Songjiang District, Shanghai) and used high-throughput sequencing techniques to reveal the diversity and community composition of soil bacteria and soil fungi in this peri-urban area. We found a total of 632 bacteria OTUs (operational taxonomic units) and 593 fungi OTUs in Maogang, in which the dominant microbial groups were Proteobacteria (bacteria) and Ascomycota (fungi). The Shannon Wiener index of soil bacteria was found to be in the range of 4.41 to 4.71, and the soil fungi’s Shannon Wiener index was found to be in the range of 1.99 to 2.60. Land-use type insignificantly affected α diversity of soil bacteria and soil fungi; however, land-use type significantly affected β diversity of soil bacteria (R = 0.32, p = 0.001) and soil fungi (R = 0.22, p = 0.001). Lastly, there were significant correlations observed between three soil environmental factors—namely, soil pH, porosity, and moisture—and community composition and β diversity of soil bacteria and soil fungi.

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    Effects of floating-bed planting on the retention of heavy metals by emergent hydrophytes
    Sicheng HUANG, Chunfu TONG, Yiping ZHU
    2023, 2023 (3):  33-42.  doi: 10.3969/j.issn.1000-5641.2023.03.004
    Abstract ( 174 )   HTML ( 16 )   PDF (838KB) ( 87 )   Save

    In this study, the effects of floating-bed planting on the retention characteristics of heavy metals by emergent hydrophytes in Jinze of Shanghai was studied. A series of sampling sites were set up in the reservoir at the bankside and the floating bed area, respectively.Cyperus alternifolius, Canna indica, andIris tectorum were selected as the representative emergent hydrophyte species to analyze the effects of floating-bed planting on the retention of Cu, Zn, Fe, Cr, Cd, and Pb in plants. The results showed that the biomass of C. indica and I. tectorum that were planted on the floating bed was significantly higher than those planted on the bankside (p < 0.05), while the biomass of C. alternifolius planted on the floating bed was significantly lower than those that were planted on the bankside (p < 0.05). The Cu, Fe, and Pb contents of C. indica planted on the floating bed, moreover, were significantly higher than those that were planted on the bankside (p < 0.05). The Cu, Zn, and Cd contents of C. alternifolius and I. tectorum planted on the floating bed were significantly higher than those that were planted on the bankside (p < 0.05). The retention of Cu, Fe, Cd, and Pb by C. indica; Cu, Zn, Fe, Cd, and Pb by I. tectorum; and Cd by C. alternifolius planted on the floating bed was significantly higher than those that were planted on the bankside (p < 0.05). In summary, correlations between the retention of different heavy metals for the same hydrophyte varied under different planting conditions; these differences were also observed among different species. Above all, it was shown that floating-bed planting can improve the growth and heavy metal absorption capacity of emergent hydrophytes to a certain extent, which has an important effect on the corresponding retention characteristic of heavy metals. Based on the results of our research, it is recommended that C. indica and I. tectorum would be preferred as floating bed plants. For the purpose of long-term monitoring, further systematic and comprehensive studies should be carried out in the future.

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    A historical sedimentary record of glacial activity in Krossfjorden, Arctic
    Xinyue ZHANG, Bing DENG, Jinzhou DU
    2023, 2023 (3):  43-52.  doi: 10.3969/j.issn.1000-5641.2023.03.005
    Abstract ( 212 )   HTML ( 22 )   PDF (2368KB) ( 59 )   Save

    In this study, sedimentary component analysis and radioactive dating of sediment core from Krossfjorden were used to evaluate the vertical distribution of grain sizes and sedimentary changes since the 1930s. The analysis helps us to understand the environmental changes that have taken place in fjords of the high-latitude glacier front over the past few decades. The results show that the sedimentation rate (0.35 cm/a) has increased significantly since the 1990s and is about twice the rate observed historically before the 1990s (0.16 cm/a). After the 1990s, the mean and median grain size increased and sediment coarsening appeared. Moreover, the composition of grain sizes changed significantly, including a decrease in the sorting coefficient, increase in kurtosis fluctuation, and positive skewness change. Changes in the sedimentary characteristics indicate that the environment has changed in the Krossfjorden during the last thirty years. Climate change has caused rapid glacier melting, which has significantly increased the proliferation of terrigenous materials in fjords of the high-latitude glacier front.

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    Analysis on perennial herbs in the rural plant landscape of Shanghai
    Qianwen TANG, Qingyun LI, Tao LIU, Dan CHEN
    2023, 2023 (3):  53-63.  doi: 10.3969/j.issn.1000-5641.2023.03.006
    Abstract ( 225 )   HTML ( 17 )   PDF (2987KB) ( 75 )   Save

    Based on a field investigation of eleven villages in Shanghai across four seasons and statistical analysis of photos and observation data, 62 perennial herbs species, belonging to 30 families and 52 genera, were identified. Gramineae, Compositae, and Asparagaceae accounted for the majority of species observed; meanwhile, native plants accounted for a relatively low proportion, representing only 15.63% of the total. Challenges for the plant landscape include monotonous dominant species, similar landscapes, and poor growth conditions. Cluster analysis was used to classify the characteristics of the investigated perennial herbs and to select potential substitutes for underperforming species. The data can be used to optimize the allocation of plant communities and to provide a theoretical basis for improving the rural plant landscape of Shanghai.

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    Effects of combined application of water-retaining agents and organic fertilizer on soil water-holding capacity in waste dumps in open pit coal mines
    Guilin WANG, Heyi GONG, Kankan SHANG, Liangjun DA
    2023, 2023 (3):  64-70.  doi: 10.3969/j.issn.1000-5641.2023.03.007
    Abstract ( 197 )   HTML ( 19 )   PDF (677KB) ( 105 )   Save

    This study investigated the combined application of water-retaining agents and organic fertilizers to enhance the soil water-holding capacity of waste dumps in open pit coal mines by measuring the anti-evaporation capacity and water content of man-made soil. The results showed that the anti-evaporation capacity of water-retaining agents in the gel state was superior to that in the dry state. Among the tested water-retaining agents, we found that France Essen at a concentration of 5% was the optimal choice. The soil water-holding time could be prolonged by the combined application of water-retaining agents and organic fertilizers, resulting in improved soil water-holding capacity. The optimum ratio of water-retaining agents to organic fertilizer was 3‰∶20% or 5‰∶10%. The water retention time of field capacity in this area would be improved by more than one time. Our findings provide valuable insights for the scientific community regarding soil remediation in waste dumps within open pit coal mines in Northwest China.

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    Remote Sensing and Geographic Information System
    Remote sensing inversion of multi-period winter wheat canopy water content based on a genetic algorithm
    Suyun NIE, Bin YANG, Wei XIA, Yuan ZHANG
    2023, 2023 (3):  71-81.  doi: 10.3969/j.issn.1000-5641.2023.03.008
    Abstract ( 205 )   HTML ( 17 )   PDF (8950KB) ( 59 )   Save

    The remote sensing inversion of crop canopy water content is a valuable for assessing drought stress of wheat fields and implementing precision irrigation. This study aimed to quickly obtain the canopy water content during the growth period for winter wheat in North China by using multi-temporal remote sensing images of Landsat-8 OLI and Sentinel-2 MSI from January to May 2017. The regression relationship was constructed with NDWI and measured water content in a wheat field via the mixed pixel decomposition model. The genetic algorithm was then used to inverse the canopy water content. The proposed method demonstrated better performance compared to ground-truth data, with the coefficient of determination (R2) and the root mean square error (RMSE) of 0.567 and 5.6%, respectively. Additionally, the error was reduced by more than 20% when compared to the direct inversion based on NDWI. This study indicates that quantification of different linear mixing ratios of wheat canopy and background soil can effectively eliminate the influence of soil on wheat water content inversion, and is crucial for the application of remote sensing to wheat growth monitoring.

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    Emergency monitoring of remote sensing for flood inundation region based on SAR texture and LightGBM
    Cheng SUN, Fang SHEN, Rugang TANG
    2023, 2023 (3):  82-92.  doi: 10.3969/j.issn.1000-5641.2023.03.009
    Abstract ( 214 )   HTML ( 20 )   PDF (2605KB) ( 95 )   Save

    In response to the need for high timeliness and accuracy monitoring for inundation region during flood disaster, a new extraction method of water areas based on SAR texture and LightGBM was proposed. Compared with other methods, such as the SDWI water index, SVM, RF and GBDT methods, it shows that the accuracy of water extraction of river, lake and flooded area is beyond 98% and higher than other methods. Meanwhile, the operating efficiency of the proposed method is 20 ~ 100 times higher than other methods, which greatly improves the timeliness of inundation emergency monitoring during flood disaster.

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    Estuary and Coastal Research
    Fluxes and influencing factors of dissolved CH4 in coastal wetlands
    Ying ZHANG, Xiaohui ZHANG, Tingting LIU, Zhixuan YANG, Jianwu TANG
    2023, 2023 (3):  93-107.  doi: 10.3969/j.issn.1000-5641.2023.03.010
    Abstract ( 128 )   HTML ( 21 )   PDF (2489KB) ( 57 )   Save

    The process of change and factors influencing dissolved CH4 concentration and flux in the coastal wetlands of Jiuduansha (JDS) and Xisha (XS) in the Yangtze Estuary were explored. The concentration of dissolved CH4 varied significantly during the sampling period, with the highest in JDS wetland being (0.30±0.19) μmol·L–1 during autumn, while that in XS wetland being (1.16±1.52) μmol·L–1 during summer. The average dissolved CH4 concentration in XS wetland ((0.56±0.91) μmol·L–1) was slightly higher than that in JDS wetland ((0.18±0.17) μmol·L–1). Principal component analysis revealed that the temporal and spatial variations in CH4 were mainly related to seasonal variation and tidal cycling in coastal wetlands. The CH4 emission under low-temperature, high-salinity, and oxygen-rich water environments was limited. The fluxes of dissolved CH4 also showed seasonal and regional variations. The water-to-air diffusion of CH4 was the largest in autumn in JDS wetlands ((0.45±0.43) nmol·m–2·s–1) and in summer in XS wetlands ((3.34±5.21) nmol·m–2·s–1). The lateral fluxes of dissolved CH4 were maximum in autumn in JDS wetlands ((2.32±9.32) nmol·m–2·s–1) and in summer in XS wetlands ((1.66±5.06) nmol·m–2·s–1). Use of water quality parameters and dissolved CH4 concentration to fit a multiple regression equation produced a high-frequency and continuous CH4 concentration. The annual average lateral transport flux (JDS wetland: 1.46 mg·m–2·d–1; XS wetland: 0.34 mg·m–2·d–1) and annual average vertical diffusion flux (JDS wetland: 1.85 mg·m–2·d–1; XS wetland: 2.90 mg·m–2·d–1) of dissolved CH4 was calculated. The results show that dissolved CH4 in coastal wetlands is an important sources of CH4 in the atmosphere and coastal waters.

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    Growth response of Heterosigma akashiwo to the changes of CO2 concentration, temperature and nutrient
    Anqiang YANG, Lixia ZHAO, Shuzhen SONG, Jie LIU, Yanlong HE, Yanna WANG
    2023, 2023 (3):  108-117.  doi: 10.3969/j.issn.1000-5641.2023.03.011
    Abstract ( 296 )   HTML ( 23 )   PDF (1212KB) ( 93 )   Save

    Heterosigma akashiwo is one of the species of harmful algal blooms (HABs) threatening marine ecosystems and the fishing industry across coastal waters worldwide. With increasing global levels of atmospheric CO2 and global warming, HABs have increased in prevalence, duration, and geographic span; this phenomenon has been further stressed by intensified anthropogenic influences, such as eutrophication. Through controlled experiments with different nutrients, CO2 concentrations, and temperatures, our study aimed to understand the response of H. akashiwo to different nutrients with changes in climate. In all simulated CO2 and temperature scenarios, both cell density and the specific growth rate of H. akashiwo in the low phosphorus groups were significantly lower than those in the high phosphorus groups. Furthermore, the maximum cell density and specific growth rate of H. akashiwo were significantly enhanced by increased CO2, while the specific growth rate was accelerated by the dual effect of increased CO2 levels and temperature. The growth response of H. akashiwo to CO2 and temperature was similar between different nutrient treatments. Taken together, the results indicate that phosphorus concentration could be the major factor controlling the growth of H. akashiwo, and the intensity and risk of H. akashiwo blooming in the future is increasing. Hence, controlling the increase of nutrients, particularly phosphate, could be a critical pathway to decrease the occurrence of H. akashiwo blooms. In summary, our case study provides scientific support for marine ecological management of HABs.

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    Metabolic potential and environmental adaptation mechanisms of Nitrospira in tidal flat wetlands
    Guohao CHEN, Tieqiang MAO, Hongpo DONG, Yafei OU, Jiawei ZHANG
    2023, 2023 (3):  118-131.  doi: 10.3969/j.issn.1000-5641.2023.03.012
    Abstract ( 229 )   HTML ( 18 )   PDF (1308KB) ( 148 )   Save

    To understand the metabolic potential and environmental adaptation mechanisms of Nitrospira in tidal flat wetlands, 14 high-quality Nitrospira genomes were constructed from five tidal flat wetlands along the coast of China using metagenomic binning and assembly methods. Phylogenetic analysis showed that among these genomes, three belonged to Comammox (complete ammonia oxidizer), nine belonged to lineage II and IV of Nitrospira, and two belonged to lineage III, which has yet to be discovered; taken together, this data suggests that abundant and diverse Nitrospira are present in China’s tidal flat wetlands. Metabolic reconstruction revealed that these Comammox and Nitrospira contained cyanase, urease, and other enzymes involved in the degradation of nitrile compounds and amide compounds; hence, they may utilize the organic nitrogen as energy by coupling with ammonia-oxidizing microorganisms. In addition, Nitrospira possessed flexible strategies to resist environmental stresses such as viral attack and osmotic changes. These results provide insights on the diversity, ecological function, and environmental adaptation mechanisms of Nitrospira from tidal wetlands.

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    Responses of saltwater intrusion in the Changjiang Estuary to various river discharge under a persistent and strong northerly wind
    Wei QIU, Jianrong ZHU
    2023, 2023 (3):  132-146.  doi: 10.3969/j.issn.1000-5641.2023.03.013
    Abstract ( 179 )   HTML ( 19 )   PDF (6717KB) ( 145 )   Save

    In February 2014, a persistent and strong northerly wind caused an extremely severe saltwater intrusion event in the Changjiang Estuary, which posed a threat to the safety of water intake from this source. Increasing river discharge from upstream reservoirs in the river basin is a method to combat severe saltwater intrusion. To simulate and analyze the effects of various river discharges on saltwater intrusion, we used the Unstructured quadrilateral grid, Finite-differencing, Estuarine and Coastal three-dimensional Ocean numerical Model (UnFECOM). By taking into account realistic river discharge and wind conditions, the model accurately reproduced the extremely severe saltwater intrusion process that occurred in February 2014. Our findings indicated that the net water flux (NWF) across the section at the upper reaches of the North Channel (NC) remained landward during the most critical period of saltwater intrusion from February 10 to 13, 2014, despite the increase in river discharge. However, the magnitude of NWF tended to decrease with increasing river discharge. The net water diversion ratio (WDR), NWF (Net Water Flux), and salt flux increased with the increase in river discharge. Under realistic river discharge conditions, WDR was –29% (the negative sign indicates that the NWF is landward), NWF was –2300 m 3/s, and the net salt flux (NSF) was –68 t/s, indicating that the NWF and NSF were landward due to the landward Ekman transport effect induced by the persistent severe northly wind. When the river discharge increased by 3000 m 3/s, WDR and NWF across the section were nearly zero, and NSF was –34 t/s. When the river discharge increased by 8000 m 3/s, WDR was 21.5% and NWF was seaward, at 3550 m3/s. NSF was –6 t/s and landward. At the water intake of Qingcaosha Reservoir, the longest continuous unsuitable water intake time decreased slightly when the river discharge increased by less than 4000 m 3/s. When the river discharge increased to 5000 m3/s, the longest continuous unsuitable water intake time decreased significantly to 10.5 days. It may be challenging to achieve the necessary value and duration of river discharge increase required for the actual operation of the Three Gorges Reservoir. To ensure the safety of water intake, implementing an early warning and forecasting system for saltwater intrusion and storing water into the reservoir at a high level before the intrusion occurs are recommended as effective methods.

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    Temporal and spatial characteristics of residual currents and net fluxes in the eastern waters of Macao during the summer
    Fenghua YU, Shenguang FANG, Yong HE, Qing HE
    2023, 2023 (3):  147-157.  doi: 10.3969/j.issn.1000-5641.2023.03.014
    Abstract ( 215 )   HTML ( 14 )   PDF (3364KB) ( 95 )   Save

    This study analyzed the spatial and temporal variations of depth-averaged residual currents of Eulerian, Lagrangian, and Stokes during a tidal cycle in the eastern waters of Macao. Data were collected for 15 days during the summer from two field stations using a method specifically designed to deal with stratified residual flow. Our findings revealed similar dynamical characteristics during flood and ebb tides in the southeast and northeast waters of Macao, with currents being more pow-erful in the southeast. We found that the material carried by the tidal current tends to travel northwest at the station A6 and southeast at A7, with Lagrange residuals being around 2.2 cm/s and 5.1 cm/s, respectively, which is slightly smaller than Eulerian residuals. Influenced by the southwest monsoon, the directions of Euler, Lagrangian, and Stokes surface residual currents on the surface generally pointed northeast. Furthermore, our results showed that the depth-averaged residuals during a tidal cycle pointed towards the open sea during upstream flooding, towards nearshore in northeast waters, and towards the east in southeast waters under non-flooding conditions. The intensity of Stokes drift in southeast waters was primarily influenced by wind on the water surface, while the effect of wind on the northeast waters was limited and weakened by enhanced runoff. The intensity and direction of transportation in both southeast and northeast waters were related to wind speeds on the sea surface. During summer, analysis of net tidal flux indicated a relatively stable counterclockwise residual current circulation in the waters downstream to the outlet of the Macao waterway. This circulation was driven by the strong northeast littoral current outside the Pearl River Estuary, leading to the formation of an east-west flowing structure compensated in the east waters of Macao. During this season, part of the tidal sediment was intercepted by this unique dynamic structure discharged by east four mouths in the Lingdingyang Estuary upstream and re-entered the Macao waters with rising tidal water, which leaded to sedimentation of beaches and troughs and poor water exchange.

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    Impact of coastal ecological restoration project on bird diversity and community dynamics
    Kun HE, Ziyu ZHANG, Annan SONG, Qifan SHEN, Jiayi WANG, Xuechu CHEN
    2023, 2023 (3):  158-166.  doi: 10.3969/j.issn.1000-5641.2023.03.015
    Abstract ( 276 )   HTML ( 27 )   PDF (831KB) ( 147 )   Save

    Yingwuzhou Wetland is an artificially restored coastal salt marsh wetland aimed at improving ecosystem services. Development of the wetland has restored the original damaged coastal ecosystem through comprehensive coastline ecological engineering measures. The birds in the study site have been investigated and researched using the route survey method since 2018, and changes in the bird population and species diversity have been analyzed to evaluate the effectiveness of coastal zone ecological restoration projects and the impact of different wetland habitat types on bird diversity. The results showed that 67 bird species were recorded in the wetland, belonging to 13 orders and 32 families, with the largest number of birds belonging to Passeriformes, including 42 species belonging to 18 families. There were 35 species of resident birds, 24 species of winter migratory birds, 10 species of summer migratory birds, and 8 species of migratory birds. Among these, one species of national class I and seven species of class II are in the List of Key Protected Wild Animals in China, respectively. Remiz consobrinus, Gallinula chloropus, Acridotheres cristatellus, Tachybaptus ruficollis, Spodiopsar cineraceus, Hirundo rustica, and Passer montanus were the dominant species. The number of wetland bird species increased annually. There were significant differences in the bird species, quantity, and Shannon–Wiener indexes among different seasons. The declining trends of bird species, quantity, and Shannon–Wiener index were in the orders of fall > winter > spring > summer, fall > winter > summer > spring, and fall > spring > winter > summer, respectively. The bird numbers and species were the highest in the natural wetland complex area. Declining trends of the Shannon–Wiener index in different habitat areas were observed for the natural wetland complex area, salt marsh wetland restoration area, clear water conservation area, lawn activity area, and wetland purification exhibition area. The ecological restoration of the coastline has enriched the bird diversity of the wetland. Habitats with rich patch types and high patch mosaic have a markedly positive impact on bird diversity. The results of this study can provide a scientific basis for the coastal ecological restoration and sustainable development of coastline wetlands.

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    Effects of coastal engineering and biological invasion on changes in the coastal pattern of Nanhui Dongtan, Shanghai
    Tingyu ZHANG, Lin YUAN, Chao ZHANG, Yang LI, Zhiyuan ZHAO, Yuxiao SHI, Liquan ZHANG, Jinghua GU
    2023, 2023 (3):  167-180.  doi: 10.3969/j.issn.1000-5641.2023.03.016
    Abstract ( 236 )   HTML ( 18 )   PDF (2515KB) ( 142 )   Save

    Under the dual influence of human activities and natural factors, the coastal zone patterns are prone to rapid changes which can directly or indirectly affect the structure, function, and sustainable development of the coastal ecosystem. Using the coastal zone of Nanhui Dongtan in Shanghai as a typical research area, we used remote sensing interpretation, sea chart digitization, and field investigation to analyze changes in spatial patterns and changes in coastal zones over the last 20 years (from 2000 to 2020). In addition, the effects of coastal engineering (including reclamation engineering and siltation promotion engineering) and S. alterniflora invasion on coastal pattern dynamics were analyzed. The results showed that: ① Since 2000, under the influence of coastal engineering and biological invasion, the land use types of Nanhui Dongtan coastal zone changed from a simple pattern dominated by coastal wetlands to a complex pattern which included multiple land use types (i.e. coastal wetlands, inland wetlands, constructed wetlands, farmland, and construction land). ② Coastal reclamation engineering decreased 11894.7 hm2 of coastal wetlands in the Nanhui Dongtan coastal zone from 2000 to 2005. The reclaimed coastal wetlands were transferred into land use types such as rice fields, ponds, and farmland due to human activities; the reclamation engineering promoted deposition of sediment in the estuary and tidal mudflat (above 0 m) and the intertidal salt marsh developed with increased rates of 320.5 hm2/a and 110.9 hm2/a, respectively; meanwhile, the siltation rate decreased to 286.8 hm2/a and 15.7 hm2/a, respectively, after 2015. After 10 years (2005—2015) of natural recovery, the area of coastal wetlands did not reach the levels seen before reclamation in Year 2000. ③ Two types of siltation promotion engineering—hard siltation promotion engineering and biological siltation promotion engineering—have both significantly promoted the rapid development of coastal wetlands in Nanhui Dongtan. Hard silting promotion engineering with propagation rates of 516.9 hm2/a in tidal mudflats (above 0 m) and 915.7 hm2/a in intertidal salt marshes, respectively, was 5.4 times and 13.9 times higher than rates observed in non-siltation areas; hence, the effects were more significant than biological siltation promotion engineering which only resulted in pattern changes in a limited area between the seawall and the wave dissipation dike by planting S. alterniflora. ④ After introducing S. alterniflora in Nanhui Dongtan, it became the most dominant plant in the Nanhui Dongtan salt marsh, accounting for 56% of the total area; this significantly changed the ecological structure and function of coastal wetlands in 2020. Coastal engineering and biological invasion have a great impact on coastal zone patterns. Although the coastal ecosystem showed a certain resilience to coastal human activities, changes in the wetland type, area, and function were difficult or impossible to recover at a great cost in the future. How to integrate the ecological functions of coastal wetlands and inland wetlands through the implementation of coastal zone restoration, ecological protection, and other measures to achieve the sustainable and healthy development of coastal zones is an important problem for future land and sea planning.

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    Assessment of land use exposure to coastal erosion in the delta region and its implications on spatial planning: An example from the Pudong New Area of Shanghai
    Xiaoting WANG, Hualong LUAN, Weiguo ZHANG, Nina Siu-Ngan LAM
    2023, 2023 (3):  181-193.  doi: 10.3969/j.issn.1000-5641.2023.03.018
    Abstract ( 210 )   HTML ( 16 )   PDF (2164KB) ( 214 )   Save

    In the context of rising sea-levels under global warming and fluvial sediment load decline, the risk of coastal erosion is increasing in global deltas. Evaluating the delta morphological change and its vulnerability to erosion in the future and analyzing land use exposure to coastal erosion, is of great significance for spatial planning, disaster prevention and mitigation, and the sustainable development of coastal regions. In this study, Pudong New Area of Shanghai, which is located in the Yangtze River Delta, was selected to compare its coastal erosion vulnerability in 2016 and 2035 using bathymetry of 2016 and modelled bathymetry of 2035 under a scenario of fluvial sediment load of 125 Mt/a and a cumulative sea-level rise of 16.5 cm. A comparison of land use exposure is made between the pattern in 2019 and the pattern projected for 2035 by the government. The results show that the spatial pattern of coastal erosion vulnerability is controlled by the morphological evolution of the delta over the last 1000 years. Coastal sections with high and very high categories of land use exposure and erosion vulnerability in the recent past (2016—2019) total 32.3 km in length, which accounts for 31.1% of the coast of the Pudong New Area. These figures are projected to be 47.5 km and 45.8%, respectively, in 2035, under the condition of reduced fluvial sediment load and planned land usage. In 2035, coastal sections along the Pudong Airport and Luchaogang will face an increase of erosion vulnerability category. According to the current plan, these two sections also show an increase in land use exposure due to airport expansion and new city development. The results suggest that these sections require erosion monitoring and erosion management during implementation of the plan. The methods used in this study can provide references for exposure assessment of coastal erosion and the formulation of territorial planning in coastal regions elsewhere.

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