We measured organic carbon input and content of soil in two wetland areas of Chongming Dongtan （Yangtze River Estuary） to evaluate variability in organic carbon accumulation capability in different wetland soils. Ob...We measured organic carbon input and content of soil in two wetland areas of Chongming Dongtan （Yangtze River Estuary） to evaluate variability in organic carbon accumulation capability in different wetland soils. Observed differences were investigated based on the microbial activity and environmental factors of the soil at the two sites. Results showed that the organic carbon content of wetland soil vegetated with Phragmites australis （site A） was markedly lower than that with P. australis and Spartina alterniflora （site B）. Sites differences were due to higher microbial activity at site A, which led to higher soil respiration intensity and greater carbon outputs. This indicated that the capability of organic carbon accumulation of the site B soils was greater than at site A. In addition, petroleum pollution and soil salinity were different in the two wetland soils. After bio-remediation, the soil petroleum pollution at site B was reduced to a similar level of site A. However, the culturable microbial biomass and enzyme activity in the remediated soils were also lower than at site A. These results indicated that greater petroleum pollution at site B did not markedly inhibit soil microbial activity. Therefore, differences in vegetation type and soil salinity were the primary factors responsible for the variation in microbial activity, organic carbon output and organic carbon accumulation capability between site A and site B.展开更多
The analysis of vegetation-environment relationships has always been a study hotspot in ecology. A number of biotic, hydrologic and edaphic factors have great influence on the distribution of macrophytes within salt m...The analysis of vegetation-environment relationships has always been a study hotspot in ecology. A number of biotic, hydrologic and edaphic factors have great influence on the distribution of macrophytes within salt marsh.Since the exotic species Spartina alterniflora（S. alterniflora） was introduced in 1995, a rapid expansion has occurred at Chongming Dongtan Nature Reserve（CDNR） in the Changjiang（Yangtze） River Estuary, China.Several important vegetation-environment factors including soil elevation, tidal channels density（TCD）,vegetation classification and fractional vegetation cover（FVC） were extracted by remote sensing method combined with field measurement. To ignore the details in interaction between biological and physical process,the relationship between them was discussed at a large scale of the whole saltmarsh. The results showed that Scirpus mariqueter（S. mariqueter） can endure the greatest elevation variance with 0.33 m throughout the marsh in CDNR. But it is dominant in the area less than 2.5 m with the occurrence frequency reaching 98%. S. alterniflora has usually been found on the most elevated soils higher than 3.5 m but has a narrow spatial distribution. The rapid decrease of S. mariqueter can be explained by stronger competitive capacity of S. alterniflora on the high tidal flat. FVC increases with elevation which shows significant correlation with elevation（r=0.30, p〈0.001）. But the frequency distribution of FVC indicates that vegetation is not well developed on both elevated banks near tidal channels from the whole scale mainly due to tidal channel lateral swing and human activities. The significant negative correlation（r=–0.20, p〈0.001） was found between FVC and TCD, which shows vegetation is restricted to grow in higher TCD area corresponding to lower elevation mainly occupied by S. mariqueter communities. The maximum occurrence frequency of this species reaches to 97% at the salt marsh with TCD more than 8 m/m2.展开更多
Dongtan is set to be developed as a sustainable urban-rural integration,aiming to attract a wide range of commercial and leisure investments.The Shanghai Industrial Investment Corporation(SIIC),the largest internation...Dongtan is set to be developed as a sustainable urban-rural integration,aiming to attract a wide range of commercial and leisure investments.The Shanghai Industrial Investment Corporation(SIIC),the largest international investment group owned by the Shanghai municipal government,is leading the Dongtan project in partnership with Arup.The project’s risks are categorized into eight major groups:(1)Force majeure,(2)people-related risks,(3)financial and economic risks,(4)political and country risks,(5)environmental risks,(6)completion-related risks,(7)design-related risks,and(8)technology risks.Among these,political risk is particularly notable for its high probability and significant impact.Effective project risk management is essential to foresee and address uncertainties that could jeopardize the project’s objectives and timelines.Appropriate strategies must be implemented to manage and mitigate these risks.展开更多
Variable and unpredictable food resources at stopover sites bring severe challenges to migrating shorebirds. Opportunistic foraging strategies, referring to shorebirds consuming prey in proportion to their availabilit...Variable and unpredictable food resources at stopover sites bring severe challenges to migrating shorebirds. Opportunistic foraging strategies, referring to shorebirds consuming prey in proportion to their availability, allow shorebirds to replenish fuel and nutrient reserves efficiently for continuing their migration. Chongming Dongtan, located in the Yangtze River estuary of eastern China, is the first major stopover site of shorebirds on the Chinese mainland during their northward migration. We investigated the diet of Great Knots (Calidris tenuirostris) at Chongming Dongtan during the spring stopovers of 2009 and 2010 through benthos sampling and dropping analysis. The benthos samples were categorized into gastropods, bivalves, polychaetes, crustaceans and insect larvae. Dropping analysis indicated that gastropods and bivalves constituted more than 70% of the diet of the Great Knot, with Assiminea violacea and Corbicula fluminea being the most frequently consumed. Chi-square tests indicated that for each prey category, there was no significant difference between the frequency of its occurrence in the benthos samples and dropping samples during the early stopover periods of 2009 and 2010 and during the late stopover periods of 2010. Although there was a statistically significant difference between the frequency of occurrence of prey in the total macrobenthos and in the droppings of the Great Knots during the late stopover period in 2009, the more abundant prey were more frequently consumed by the Great Knots. This suggests that Great Knots adopted an opportunistic foraging strategy during their stopover at Chongming Dongtan.展开更多
The spectral reflectance of recently formed salt marshes at the mouth of the Yangtze River,which are undergoing invasion by Spartina alterniflora,were assessed to determine the potential utility of remotely sensed dat...The spectral reflectance of recently formed salt marshes at the mouth of the Yangtze River,which are undergoing invasion by Spartina alterniflora,were assessed to determine the potential utility of remotely sensed data in assessing future invasion and changes in species composition.Following a review of published research on remote sensing of salt marshes,53 locations along three transects were sampled for paired data on plant species composition and spectral reflectance using a FieldSpecTM Pro JR Field Portable Spectroradiometer.Spectral data were processed concerning reflectance,and the averaged reflectance values for each sample were reanalysed to correspond to a 12-waveband bandset of the Compact Airborne Spectral Imager.The spectral data were summarised using principal components analysis(PCA)and the relationships between the vegetation composition,and the PCA axes of spectral data were examined.The first PCA axis of the reflectance data showed a strong correlation with variability in near infrared reflectance and‘brightness’,while the second axis was correlated with visible reflectance and‘greenness’.Total vegetation cover,vegetation height,and mudflat cover were all significantly related to the first axis.The implications of this in terms of the ability of remote sensing to distinguish the various salt marsh species and in particular the invasive species S.alterniflora were discussed.Major differences in species with various physiognomies could be recognised but problems occurred in separating early colonising S.alterniflora from other species at that stage.Further work using multi-seasonal hyperspectral data might assist in solving these problems.展开更多
With climate change and rising sea levels,the coastal zone’s flood risk is deteriorating.Previous researches have shown a gradually degrading capacity of traditional hard engineering structures(e.g.,seawall,dikes)on ...With climate change and rising sea levels,the coastal zone’s flood risk is deteriorating.Previous researches have shown a gradually degrading capacity of traditional hard engineering structures(e.g.,seawall,dikes)on flood mitigation due to problems such as land subsidence and insufficient maintenance.To remedy the defects,the"building with nature concept"for coastal protection with saltmarshes was examined by combining field measurements and numerical simulations.The advantages of saltmarsh over traditional seawall on flood protection was demonstrated from the perspective of both flood area mitigation and economic gain,based on scenario simulations.Results show that tidal wetlands are essential in mitigating significant wave heights(Hs)and current velocities even during storm conditions.The storm wave and current velocity reduction ratio(RRw and RRc)by saltmarshes on Chongming Dongtan Shoal(CMDS)during Typhoon 9711 is approximately 11%and 51%,respectively.The wave and current mitigation by Scirpus mariqueter are more efficient than Spartina alterniflora and Phragmites australis during measurements in 2010,which were approximately 0.3 m and 0.2 m/s,0.125 m and 0.155 m/s,0.086 m and 0.128 m/s per kilometer width,respectively.The summer saltmarsh area 54.2 km2 on CMDS protects approximately 32 km^(2)land area behind the seawall from being flooded,equivalent to the seawall heightening of approximately 0.42 m on equivalent flood mitigation.The performance of cost-and-benefit analysis shows a relatively higher(by 3%–7%)net present value(NPV)and a higher(by 1.5 times)benefit-cost ratio(BC)of nature-based solution(i.e.,saltmarsh restoration)compared with traditional hard engineering solution(i.e.,seawall construction).Thus,building seawall with nature,such as a hybrid flood protection measure,should be implemented in the future coastal redesign and maintenance.展开更多
China is a country whose natural resources are groaning under the weight of new demands. The World Bank estimates that every year twenty million people move into the nation's rapidly expanding cities. The environm...China is a country whose natural resources are groaning under the weight of new demands. The World Bank estimates that every year twenty million people move into the nation's rapidly expanding cities. The environmental pressure resulting from this urbanisation is extreme as low quality, inefficient housing is thrown up and enormous road展开更多
基金supported by the National Key Scientific and Technological Project (No.2006BAC01A14)the Shanghai Key Scientific and Technological Project (No.06DZ12302)
文摘We measured organic carbon input and content of soil in two wetland areas of Chongming Dongtan （Yangtze River Estuary） to evaluate variability in organic carbon accumulation capability in different wetland soils. Observed differences were investigated based on the microbial activity and environmental factors of the soil at the two sites. Results showed that the organic carbon content of wetland soil vegetated with Phragmites australis （site A） was markedly lower than that with P. australis and Spartina alterniflora （site B）. Sites differences were due to higher microbial activity at site A, which led to higher soil respiration intensity and greater carbon outputs. This indicated that the capability of organic carbon accumulation of the site B soils was greater than at site A. In addition, petroleum pollution and soil salinity were different in the two wetland soils. After bio-remediation, the soil petroleum pollution at site B was reduced to a similar level of site A. However, the culturable microbial biomass and enzyme activity in the remediated soils were also lower than at site A. These results indicated that greater petroleum pollution at site B did not markedly inhibit soil microbial activity. Therefore, differences in vegetation type and soil salinity were the primary factors responsible for the variation in microbial activity, organic carbon output and organic carbon accumulation capability between site A and site B.
基金Program Strategic Scientific Alliances between China and the Netherlands under contract No.2008DFB90240Open Research Fund Program for State Key Laboratory of Estuarine and Coastal Research under contract No.SKLEC201207Open Research Fund Program for Shandong Province Key Laboratory of Marine Ecology Environment and Disaster Prevention under contract No.2012011
文摘The analysis of vegetation-environment relationships has always been a study hotspot in ecology. A number of biotic, hydrologic and edaphic factors have great influence on the distribution of macrophytes within salt marsh.Since the exotic species Spartina alterniflora（S. alterniflora） was introduced in 1995, a rapid expansion has occurred at Chongming Dongtan Nature Reserve（CDNR） in the Changjiang（Yangtze） River Estuary, China.Several important vegetation-environment factors including soil elevation, tidal channels density（TCD）,vegetation classification and fractional vegetation cover（FVC） were extracted by remote sensing method combined with field measurement. To ignore the details in interaction between biological and physical process,the relationship between them was discussed at a large scale of the whole saltmarsh. The results showed that Scirpus mariqueter（S. mariqueter） can endure the greatest elevation variance with 0.33 m throughout the marsh in CDNR. But it is dominant in the area less than 2.5 m with the occurrence frequency reaching 98%. S. alterniflora has usually been found on the most elevated soils higher than 3.5 m but has a narrow spatial distribution. The rapid decrease of S. mariqueter can be explained by stronger competitive capacity of S. alterniflora on the high tidal flat. FVC increases with elevation which shows significant correlation with elevation（r=0.30, p〈0.001）. But the frequency distribution of FVC indicates that vegetation is not well developed on both elevated banks near tidal channels from the whole scale mainly due to tidal channel lateral swing and human activities. The significant negative correlation（r=–0.20, p〈0.001） was found between FVC and TCD, which shows vegetation is restricted to grow in higher TCD area corresponding to lower elevation mainly occupied by S. mariqueter communities. The maximum occurrence frequency of this species reaches to 97% at the salt marsh with TCD more than 8 m/m2.
文摘Dongtan is set to be developed as a sustainable urban-rural integration,aiming to attract a wide range of commercial and leisure investments.The Shanghai Industrial Investment Corporation(SIIC),the largest international investment group owned by the Shanghai municipal government,is leading the Dongtan project in partnership with Arup.The project’s risks are categorized into eight major groups:(1)Force majeure,(2)people-related risks,(3)financial and economic risks,(4)political and country risks,(5)environmental risks,(6)completion-related risks,(7)design-related risks,and(8)technology risks.Among these,political risk is particularly notable for its high probability and significant impact.Effective project risk management is essential to foresee and address uncertainties that could jeopardize the project’s objectives and timelines.Appropriate strategies must be implemented to manage and mitigate these risks.
基金supported by the National Natural Science Foundation of China(Grant No.30670269,31071939)
文摘Variable and unpredictable food resources at stopover sites bring severe challenges to migrating shorebirds. Opportunistic foraging strategies, referring to shorebirds consuming prey in proportion to their availability, allow shorebirds to replenish fuel and nutrient reserves efficiently for continuing their migration. Chongming Dongtan, located in the Yangtze River estuary of eastern China, is the first major stopover site of shorebirds on the Chinese mainland during their northward migration. We investigated the diet of Great Knots (Calidris tenuirostris) at Chongming Dongtan during the spring stopovers of 2009 and 2010 through benthos sampling and dropping analysis. The benthos samples were categorized into gastropods, bivalves, polychaetes, crustaceans and insect larvae. Dropping analysis indicated that gastropods and bivalves constituted more than 70% of the diet of the Great Knot, with Assiminea violacea and Corbicula fluminea being the most frequently consumed. Chi-square tests indicated that for each prey category, there was no significant difference between the frequency of its occurrence in the benthos samples and dropping samples during the early stopover periods of 2009 and 2010 and during the late stopover periods of 2010. Although there was a statistically significant difference between the frequency of occurrence of prey in the total macrobenthos and in the droppings of the Great Knots during the late stopover period in 2009, the more abundant prey were more frequently consumed by the Great Knots. This suggests that Great Knots adopted an opportunistic foraging strategy during their stopover at Chongming Dongtan.
基金This research was funded by the Key Project of the Shanghai Science and Technology Committee(Grant No.06DZ12302)National Basic Research Program of China(Grant No.2004CB720505).
文摘The spectral reflectance of recently formed salt marshes at the mouth of the Yangtze River,which are undergoing invasion by Spartina alterniflora,were assessed to determine the potential utility of remotely sensed data in assessing future invasion and changes in species composition.Following a review of published research on remote sensing of salt marshes,53 locations along three transects were sampled for paired data on plant species composition and spectral reflectance using a FieldSpecTM Pro JR Field Portable Spectroradiometer.Spectral data were processed concerning reflectance,and the averaged reflectance values for each sample were reanalysed to correspond to a 12-waveband bandset of the Compact Airborne Spectral Imager.The spectral data were summarised using principal components analysis(PCA)and the relationships between the vegetation composition,and the PCA axes of spectral data were examined.The first PCA axis of the reflectance data showed a strong correlation with variability in near infrared reflectance and‘brightness’,while the second axis was correlated with visible reflectance and‘greenness’.Total vegetation cover,vegetation height,and mudflat cover were all significantly related to the first axis.The implications of this in terms of the ability of remote sensing to distinguish the various salt marsh species and in particular the invasive species S.alterniflora were discussed.Major differences in species with various physiognomies could be recognised but problems occurred in separating early colonising S.alterniflora from other species at that stage.Further work using multi-seasonal hyperspectral data might assist in solving these problems.
基金The National Natural Science Foundation of China under contract Nos 51761135024,42171282 and 41701001the Key Projects of Intergovernmental Science and Technology Innovation Cooperation of the Ministry of Science and Technology in China under contract No.2018YFE0109900+1 种基金the International Science&Technology Cooperation s of Shanghai Science and Technology Commission under contract No.19230712400the China Postdoctoral Science Foundation under contract No.2018M630414。
文摘With climate change and rising sea levels,the coastal zone’s flood risk is deteriorating.Previous researches have shown a gradually degrading capacity of traditional hard engineering structures(e.g.,seawall,dikes)on flood mitigation due to problems such as land subsidence and insufficient maintenance.To remedy the defects,the"building with nature concept"for coastal protection with saltmarshes was examined by combining field measurements and numerical simulations.The advantages of saltmarsh over traditional seawall on flood protection was demonstrated from the perspective of both flood area mitigation and economic gain,based on scenario simulations.Results show that tidal wetlands are essential in mitigating significant wave heights(Hs)and current velocities even during storm conditions.The storm wave and current velocity reduction ratio(RRw and RRc)by saltmarshes on Chongming Dongtan Shoal(CMDS)during Typhoon 9711 is approximately 11%and 51%,respectively.The wave and current mitigation by Scirpus mariqueter are more efficient than Spartina alterniflora and Phragmites australis during measurements in 2010,which were approximately 0.3 m and 0.2 m/s,0.125 m and 0.155 m/s,0.086 m and 0.128 m/s per kilometer width,respectively.The summer saltmarsh area 54.2 km2 on CMDS protects approximately 32 km^(2)land area behind the seawall from being flooded,equivalent to the seawall heightening of approximately 0.42 m on equivalent flood mitigation.The performance of cost-and-benefit analysis shows a relatively higher(by 3%–7%)net present value(NPV)and a higher(by 1.5 times)benefit-cost ratio(BC)of nature-based solution(i.e.,saltmarsh restoration)compared with traditional hard engineering solution(i.e.,seawall construction).Thus,building seawall with nature,such as a hybrid flood protection measure,should be implemented in the future coastal redesign and maintenance.
文摘China is a country whose natural resources are groaning under the weight of new demands. The World Bank estimates that every year twenty million people move into the nation's rapidly expanding cities. The environmental pressure resulting from this urbanisation is extreme as low quality, inefficient housing is thrown up and enormous road
