The horizontal structure of mangrove forests is an important characteristic that reflects a significant signal for coupling between mangroves and external drivers.While the loss and gain of mangroves has received much...The horizontal structure of mangrove forests is an important characteristic that reflects a significant signal for coupling between mangroves and external drivers.While the loss and gain of mangroves has received much attention,little information about how the horizontal structure of mangrove forests develops from the seedling stage to maturity has been presented.Here,remote sensing images taken over approximately 15 years,UVA images,nutrient elements,sediments,and Aegiceras corniculatum vegetation parameters of the ecological quadrats along the Nanliu Delta,the largest delta of the northern Beibu Gulf in China,are analyzed to reveal changes in the horizontal structure of mangroves and their associated driving factors.The results show that both discrete structures and agglomerated structures can often be found in A.corniculatum seedlings and saplings.However,the combination of seedlings growing into maturity and new seedlings filling in available gaps causes the discrete structure of A.corniculatum to gradually vanish and the agglomerate structure to become stable.The aggregated structure of seedlings,compared to the discrete structure,can enhance the elevation beneath mangroves by trapping significantly more sediments,providing available spaces and conditions for seedlings to continue growing.Furthermore,by catching fine sediments with enriched nutrients,the survival rate of A.corniculatum seedlings in the agglomerated structure can be much higher than that in the discrete structure.Our results highlight the significance of the agglomeration of A.corniculatum,which can be beneficial to coastal mangrove restoration and management.展开更多
Mangrove forest is one of the most important ecological and environmental resources by effectively promoting tidal flat deposition and preventing the coastal region from typhoon.However,there have been mass loss of ma...Mangrove forest is one of the most important ecological and environmental resources by effectively promoting tidal flat deposition and preventing the coastal region from typhoon.However,there have been mass loss of mangrove forests due to anthropogenic activities.It is an urgent need to explore an effective way for mangrove restoration.Here,three rows of bamboo fences with hydro-sedimentary observation set over Aegiceras corniculatum mangrove tidal flat of the Nanliu Delta,the largest delta of Beibu Gulf,China,were conducted to analyze the hydro-sedimentary variations induced by bamboo fences.Results identified that the mean horizontal velocity Um per burst(20 min)decreased by as much as 71%and 40%in comparison with those without bamboo fences in March and November,respectively,when the tidal current entering the bamboo area during flood.The maximum of mean horizontal flow velocity Um-max at bamboo area was 50%–75%of that without bamboo fences during ebb tide.The suspended sediment concentration of bamboo area suggested a maximum reduction of 57%relative to bare flat during flood,and was 80%lower than bare flat at ebb peak.Moreover,the turbulent kinetic dissipationεat flood tide was significantly higher than that at ebb tide,while the bamboo fences greatly increased the turbulent kinetic dissipationεby 2 to 5 times relative to bare flat,resulting in an increase of the bed elevation by inhibiting the sediment incipient motion and intercepting suspended sediment.The siltation rate at the bamboo area was 140%and 29.3%higher than that at the bare flat and the region covered with A.corniculatum,respectively.These results highlight that bamboo fences can effectively attenuate tidal current and thus promote siltation over mangrove flat,which contribute great benefit to mangrove survival.展开更多
In order to study the county scale land use structure during the rapid urbanization and more accurately grasp the dynamic process of land use and cover change,we combine GIS technology with CLUE-S model to research th...In order to study the county scale land use structure during the rapid urbanization and more accurately grasp the dynamic process of land use and cover change,we combine GIS technology with CLUE-S model to research the spatial pattern change of land use in Yongchuan District of Chongqing City. The results show that the forest and farmland were main land use types going through changes in Yongchuan District during 2000-2010,accounting for more than 90% of the total area in each year; during 2000- 2010,the urban area was significantly increased,an increase of 16. 11%,and the urban area during 2005- 2010 was changed more dramatically than during 2000- 2005; forest area was slightly increased and farmland area was reduced by 1660 ha in 10 years. We set three scenarios on land use change in Yongchuan District for simulation and compare the predicted results. It can be concluded that driven by rapid urbanization,the change in land use landscape pattern in Yongchuan District is mainly focused on forest and farmland,the urban area is substantially increased,and the forest area also shows an increasing trend while the farmland area is reduced accordingly. Under ecological protection scenarios,the land use type having a protective effect on the ecological environment achieves better control effect.展开更多
Mangrove forests are significant ecosystems worldwide and play a crucial role in maintaining the biodiversity of intertidal zones in tropical and subtropical regions.However,most mangroves have experienced large-scale...Mangrove forests are significant ecosystems worldwide and play a crucial role in maintaining the biodiversity of intertidal zones in tropical and subtropical regions.However,most mangroves have experienced large-scale losses due to anthropogenic activities and natural stress from environmental factors.Here,the dynamic changes in mangroves in the Dandou Sea(DDS)of the Beibu Gulf between 1987 and 2021 were analyzed via multispectral satellite remote sensing data from the Google Earth Engine Platform.The results indicated that the area of mangroves in the DDS increased from 225.90 ha in 1987 to 451.76 ha in 2021.Throughout this period,the overall mangrove area in the DDS,as well as in its western and central parts,underwent a rapid growth phase from 1987 to 1996,followed by a slow growth phase from 1997 to 2011,and eventually entered a stagnation phase from 2013 to 2021.Moreover,due to the biological invasion caused by Spartina alterniflora,the mangrove forests in this area tended toward fragmentation.Moreover,S.alterniflora suppressed the spread of mangrove forests,accounting for up to 41.69%of the total loss.In a similar vein,the local high-intensity economic activities within the tidal flat accounted for 32.55%of the mangrove loss.Additionally,the expansion of aquaculture ponds and construction land directly accounted for 9.45%and 7.91%of the mangrove loss,respectively.Furthermore,the establishment of mangrove nature reserves played a positive role in the restoration and expansion of mangroves in the DDS.Our results also demonstrated that sea level rise had little impact on mangrove retreat.展开更多
基金The National Natural Science Key Foundation of China under contract No.41930537the Key Research Base of Humanities and Social Sciences in Guangxi Universities“Beibu Gulf Ocean Development Research Center”under contract No.10BHZKY2110+1 种基金the Key Research and Development Plan of Guangxi under contract No.Guike AB21076016the Marine Science Program for Guangxi First-Class Discipline,Beibu Gulf University.
文摘The horizontal structure of mangrove forests is an important characteristic that reflects a significant signal for coupling between mangroves and external drivers.While the loss and gain of mangroves has received much attention,little information about how the horizontal structure of mangrove forests develops from the seedling stage to maturity has been presented.Here,remote sensing images taken over approximately 15 years,UVA images,nutrient elements,sediments,and Aegiceras corniculatum vegetation parameters of the ecological quadrats along the Nanliu Delta,the largest delta of the northern Beibu Gulf in China,are analyzed to reveal changes in the horizontal structure of mangroves and their associated driving factors.The results show that both discrete structures and agglomerated structures can often be found in A.corniculatum seedlings and saplings.However,the combination of seedlings growing into maturity and new seedlings filling in available gaps causes the discrete structure of A.corniculatum to gradually vanish and the agglomerate structure to become stable.The aggregated structure of seedlings,compared to the discrete structure,can enhance the elevation beneath mangroves by trapping significantly more sediments,providing available spaces and conditions for seedlings to continue growing.Furthermore,by catching fine sediments with enriched nutrients,the survival rate of A.corniculatum seedlings in the agglomerated structure can be much higher than that in the discrete structure.Our results highlight the significance of the agglomeration of A.corniculatum,which can be beneficial to coastal mangrove restoration and management.
基金The National Natural Science Key Foundation of China under contract No.41930537the Key Research and Development Plan of Guangxi under contract No.AB21076016+1 种基金the Marine Science Program for Guangxi First-Class Discipline,Beibu Gulf Universitythe China Postdoctoral Science Foundation under contract No.2022M721150.
文摘Mangrove forest is one of the most important ecological and environmental resources by effectively promoting tidal flat deposition and preventing the coastal region from typhoon.However,there have been mass loss of mangrove forests due to anthropogenic activities.It is an urgent need to explore an effective way for mangrove restoration.Here,three rows of bamboo fences with hydro-sedimentary observation set over Aegiceras corniculatum mangrove tidal flat of the Nanliu Delta,the largest delta of Beibu Gulf,China,were conducted to analyze the hydro-sedimentary variations induced by bamboo fences.Results identified that the mean horizontal velocity Um per burst(20 min)decreased by as much as 71%and 40%in comparison with those without bamboo fences in March and November,respectively,when the tidal current entering the bamboo area during flood.The maximum of mean horizontal flow velocity Um-max at bamboo area was 50%–75%of that without bamboo fences during ebb tide.The suspended sediment concentration of bamboo area suggested a maximum reduction of 57%relative to bare flat during flood,and was 80%lower than bare flat at ebb peak.Moreover,the turbulent kinetic dissipationεat flood tide was significantly higher than that at ebb tide,while the bamboo fences greatly increased the turbulent kinetic dissipationεby 2 to 5 times relative to bare flat,resulting in an increase of the bed elevation by inhibiting the sediment incipient motion and intercepting suspended sediment.The siltation rate at the bamboo area was 140%and 29.3%higher than that at the bare flat and the region covered with A.corniculatum,respectively.These results highlight that bamboo fences can effectively attenuate tidal current and thus promote siltation over mangrove flat,which contribute great benefit to mangrove survival.
基金Supported by National Natural Science Foundation of China(41171442)
文摘In order to study the county scale land use structure during the rapid urbanization and more accurately grasp the dynamic process of land use and cover change,we combine GIS technology with CLUE-S model to research the spatial pattern change of land use in Yongchuan District of Chongqing City. The results show that the forest and farmland were main land use types going through changes in Yongchuan District during 2000-2010,accounting for more than 90% of the total area in each year; during 2000- 2010,the urban area was significantly increased,an increase of 16. 11%,and the urban area during 2005- 2010 was changed more dramatically than during 2000- 2005; forest area was slightly increased and farmland area was reduced by 1660 ha in 10 years. We set three scenarios on land use change in Yongchuan District for simulation and compare the predicted results. It can be concluded that driven by rapid urbanization,the change in land use landscape pattern in Yongchuan District is mainly focused on forest and farmland,the urban area is substantially increased,and the forest area also shows an increasing trend while the farmland area is reduced accordingly. Under ecological protection scenarios,the land use type having a protective effect on the ecological environment achieves better control effect.
基金supported by the National Natural Science Key Foundation of China(NSFC)(Grant Nos.41930537 and 42366009)Marine Science Program for Guangxi First-Class Discipline,Beibu Gulf University。
文摘Mangrove forests are significant ecosystems worldwide and play a crucial role in maintaining the biodiversity of intertidal zones in tropical and subtropical regions.However,most mangroves have experienced large-scale losses due to anthropogenic activities and natural stress from environmental factors.Here,the dynamic changes in mangroves in the Dandou Sea(DDS)of the Beibu Gulf between 1987 and 2021 were analyzed via multispectral satellite remote sensing data from the Google Earth Engine Platform.The results indicated that the area of mangroves in the DDS increased from 225.90 ha in 1987 to 451.76 ha in 2021.Throughout this period,the overall mangrove area in the DDS,as well as in its western and central parts,underwent a rapid growth phase from 1987 to 1996,followed by a slow growth phase from 1997 to 2011,and eventually entered a stagnation phase from 2013 to 2021.Moreover,due to the biological invasion caused by Spartina alterniflora,the mangrove forests in this area tended toward fragmentation.Moreover,S.alterniflora suppressed the spread of mangrove forests,accounting for up to 41.69%of the total loss.In a similar vein,the local high-intensity economic activities within the tidal flat accounted for 32.55%of the mangrove loss.Additionally,the expansion of aquaculture ponds and construction land directly accounted for 9.45%and 7.91%of the mangrove loss,respectively.Furthermore,the establishment of mangrove nature reserves played a positive role in the restoration and expansion of mangroves in the DDS.Our results also demonstrated that sea level rise had little impact on mangrove retreat.
