Through densified surface sampling of foraminifera and accurate elevation measurement a-long three transect lines in open-coast tidal salt-marsh of Jianchuan, particular salt-marsh foraminifera assemblages were found....Through densified surface sampling of foraminifera and accurate elevation measurement a-long three transect lines in open-coast tidal salt-marsh of Jianchuan, particular salt-marsh foraminifera assemblages were found. The salt-marsh foraminifera assemblages are distributed in well-defined vertical zonations with respect to elevation and closely parallel marsh floral zonations. At the top of the vertical zonation all foraminifera disappear abruptly which are accurately located at the highest high water datum. This distribution pattern can be used to relocate former sea levels accurately (to an accuracy of within ±5 cm). A modern regional criterion of foraminifera for relocating the former sea levels in high resolution in our country is provided, and deficiencies of studying the vertical zonation only in sheltered coast salt-marsh abroad are filled up.展开更多
Spartina alterniflora is ecologically important in its original habitat; however, it has caused controversy since it was introduction into China(now it has been spreading rapidly on the Jiangsu, Shanghai, Zhejiang and...Spartina alterniflora is ecologically important in its original habitat; however, it has caused controversy since it was introduction into China(now it has been spreading rapidly on the Jiangsu, Shanghai, Zhejiang and Fujian coasts). The purpose of the present contribution is, on the basis of an analysis and synthesis of existing data sets, to evaluate the environmental-ecological effects of S. alterniflora, and to identify the relevant scientific problems that require further research in the future. Investigations have shown that, by reducing the near-bed shear stress associated with tidal currents, S. alterniflora can enhance the settling flux of suspended sediment and deposition rate on the tidal flats over the region. Further, field survey and analysis indicate that the S. alterniflora salt-marsh has a high primary production and provides a new type of habitat for the native benthic fauna. Some macro-, meio- and micro-fauna that used to live in the native salt-marshes have adapted to the S. alterniflora salt-marsh, forming a new ecosystem. Under the influences of a number of background factors, such as latitude variations and the coastal type, the environmental-ecological changes induced by Spartine have regional differentiations. To the north of Hangzhou Bay, with a high position of the pre-Holocene stratum base, a large width of the tidal flats, and a gentle bed slope, only a small part of the intertidal zone is occupied by the S. alterniflora salt-marsh. Here, the S. alterniflora salt-marshes mainly play a positive role in coastal protection and ecosystem functioning. In contrary, to the South of Hangzhou Bay, The pre-Holocene deposits are situated in relatively deeo waters, and the width of the tidal flats formed within coastal embayments is relatively narrow. As such, the expansion of S. alterniflora has squeezed the living space of other intertidal organisms, thus has a negative ecological effect. Therefore, the regional differentiation of the Spartina effects should be sufficiently considered in coastal development and management. Furthermore, in order to predict the future evolution of the S. alterniflora wetlands over the region, in addition to in situ monitoring and measurements, an ecosystem dynamic model should be established, taking into account the coupling of the rerrestrial and marine environmental-ecological processes.展开更多
Aims In estuarine salt-marshes,nitrate supply and soil salinity,which are known as two main environmental drivers,simultaneously affect the interspecific interactions between plant species.However,to date,their intera...Aims In estuarine salt-marshes,nitrate supply and soil salinity,which are known as two main environmental drivers,simultaneously affect the interspecific interactions between plant species.However,to date,their interactive effects on interspecific interactions have not been closely examined for salt-marsh plant species.Methods Juvenile plants of Suaeda salsa L.(Chenopodiaceae)and Scirpus planiculmis Fr.(Cyperaceae)were grown in rinsed river sand to conduct a greenhouse experiment with three treatment categories:interspecific interaction(mixed culture or monoculture),three salinity levels(1,50 and 100 mmol L^(-1))and three nitrate levels(0.5,5 and 10 mmol L^(-1)).First,height and biomass of all plants were measured.Then,the growth data,relative interaction index and competitive important index of the two species were analyzed.Important Findings The interspecific interactions between S.salsa and S.planiculmis were facilitation across the salinity gradients.The promotion of S.salsa growth with high nitrate supply did not enhance the facilitative effect of the species,especially at low salinity.However,high nitrate supply significantly shifted the interspecific interactions of S.planiculmis from facilitation to competition at high salinity.Our results suggest that excessive nitrate application changes the prediction of the stress-gradient hypothesis along a salinity gradient,leading to collapse of the two species coexistence in the salt-marshes.These findings make a contribution to the understanding of how S.salsa and S.planiculmis,as well as salt-marsh communities,respond to the human modification of estuarine nutritional levels.展开更多
基金This study was supported by the National Natural Science Foundation of China under contract No. 49671071.
文摘Through densified surface sampling of foraminifera and accurate elevation measurement a-long three transect lines in open-coast tidal salt-marsh of Jianchuan, particular salt-marsh foraminifera assemblages were found. The salt-marsh foraminifera assemblages are distributed in well-defined vertical zonations with respect to elevation and closely parallel marsh floral zonations. At the top of the vertical zonation all foraminifera disappear abruptly which are accurately located at the highest high water datum. This distribution pattern can be used to relocate former sea levels accurately (to an accuracy of within ±5 cm). A modern regional criterion of foraminifera for relocating the former sea levels in high resolution in our country is provided, and deficiencies of studying the vertical zonation only in sheltered coast salt-marsh abroad are filled up.
基金supported financially by the Basic Research Project in Jiangsu Province (Grant No. SBK2011012)an National Natural Science Foundation of China (Grant No. 40476041)
文摘Spartina alterniflora is ecologically important in its original habitat; however, it has caused controversy since it was introduction into China(now it has been spreading rapidly on the Jiangsu, Shanghai, Zhejiang and Fujian coasts). The purpose of the present contribution is, on the basis of an analysis and synthesis of existing data sets, to evaluate the environmental-ecological effects of S. alterniflora, and to identify the relevant scientific problems that require further research in the future. Investigations have shown that, by reducing the near-bed shear stress associated with tidal currents, S. alterniflora can enhance the settling flux of suspended sediment and deposition rate on the tidal flats over the region. Further, field survey and analysis indicate that the S. alterniflora salt-marsh has a high primary production and provides a new type of habitat for the native benthic fauna. Some macro-, meio- and micro-fauna that used to live in the native salt-marshes have adapted to the S. alterniflora salt-marsh, forming a new ecosystem. Under the influences of a number of background factors, such as latitude variations and the coastal type, the environmental-ecological changes induced by Spartine have regional differentiations. To the north of Hangzhou Bay, with a high position of the pre-Holocene stratum base, a large width of the tidal flats, and a gentle bed slope, only a small part of the intertidal zone is occupied by the S. alterniflora salt-marsh. Here, the S. alterniflora salt-marshes mainly play a positive role in coastal protection and ecosystem functioning. In contrary, to the South of Hangzhou Bay, The pre-Holocene deposits are situated in relatively deeo waters, and the width of the tidal flats formed within coastal embayments is relatively narrow. As such, the expansion of S. alterniflora has squeezed the living space of other intertidal organisms, thus has a negative ecological effect. Therefore, the regional differentiation of the Spartina effects should be sufficiently considered in coastal development and management. Furthermore, in order to predict the future evolution of the S. alterniflora wetlands over the region, in addition to in situ monitoring and measurements, an ecosystem dynamic model should be established, taking into account the coupling of the rerrestrial and marine environmental-ecological processes.
基金supported by the National Key R&D Program of China(2017YFC0506200).
文摘Aims In estuarine salt-marshes,nitrate supply and soil salinity,which are known as two main environmental drivers,simultaneously affect the interspecific interactions between plant species.However,to date,their interactive effects on interspecific interactions have not been closely examined for salt-marsh plant species.Methods Juvenile plants of Suaeda salsa L.(Chenopodiaceae)and Scirpus planiculmis Fr.(Cyperaceae)were grown in rinsed river sand to conduct a greenhouse experiment with three treatment categories:interspecific interaction(mixed culture or monoculture),three salinity levels(1,50 and 100 mmol L^(-1))and three nitrate levels(0.5,5 and 10 mmol L^(-1)).First,height and biomass of all plants were measured.Then,the growth data,relative interaction index and competitive important index of the two species were analyzed.Important Findings The interspecific interactions between S.salsa and S.planiculmis were facilitation across the salinity gradients.The promotion of S.salsa growth with high nitrate supply did not enhance the facilitative effect of the species,especially at low salinity.However,high nitrate supply significantly shifted the interspecific interactions of S.planiculmis from facilitation to competition at high salinity.Our results suggest that excessive nitrate application changes the prediction of the stress-gradient hypothesis along a salinity gradient,leading to collapse of the two species coexistence in the salt-marshes.These findings make a contribution to the understanding of how S.salsa and S.planiculmis,as well as salt-marsh communities,respond to the human modification of estuarine nutritional levels.
