The middle and lower reaches of the Yangtze River,a primary region for freshwater lakes in China,have undergone significant transformations throughout the Holocene.These changes,driven by factors such as sea-level ris...The middle and lower reaches of the Yangtze River,a primary region for freshwater lakes in China,have undergone significant transformations throughout the Holocene.These changes,driven by factors such as sea-level rise,climate change,and human activities,have led to the progressive elevation of water levels in this area.As a result,a floodplain has emerged,characterized by the formation of numerous shallow lakes along the river course.However,the pattern of water-level changes in the main channel of the Yangtze River during the Holocene remains unclear.This gap in knowledge poses challenges for understanding sediment transport dynamics,the interactions between the river and its adjacent lakes,and the prevention and control of flood disasters in the Yangtze River basin.To shed light on these issues,our study compiled data on the surface elevation and water depth of 81 lakes in the mid-lower reaches of the Yangtze River basin.Additionally,we analyzed historical water-level records from the 1900s to the 1970s at eight gauging stations from Shashi to Jiangyin along the river’s main stream.Our findings reveal that,particularly along the Jingjiang section,the basal elevation of most lakes is lower than the Yangtze River’s water level during the dry season.Conversely,the water level of the main stream exceeds that of both the floodplain and the lakes enclosed by the Jingjiang embankment.In the tidal reach,especially within the Taihu Lake basin,the basal elevation of lakes typically falls below sea level.Meanwhile,lakes located along the section from Chenglingji to Wuhu exhibit basal elevations that correspond with the Yangtze River’s annual average and dry season water levels.Given the widespread presence of lakes along the middle and lower reaches of the Yangtze River,our study introduces a new proxy for reconstructing the mean water level of the mid-lower Yangtze River in the Holocene.By analyzing sediments from Nanyi Lake and Chenyao Lake in the lower Yangtze River,we attempted to reconstruct the water level of展开更多
Background:The Black-faced Spoonbill(Platalea minor)is a globally threatened species,nesting mainly in western Korea with smaller numbers breeding in Liaoning Province,China,and Far East Russia.Recent winter field sur...Background:The Black-faced Spoonbill(Platalea minor)is a globally threatened species,nesting mainly in western Korea with smaller numbers breeding in Liaoning Province,China,and Far East Russia.Recent winter field surveys to estimate the species'population size were almost totally conducted in coastal areas,but tracking studies showed that some individuals now winter inland.To ensure its long-term survival,we need a more comprehensive assessment of the current distribution and abundance of the species.Methods:We combined the most recent count data and satellite tracking information to update existing informa-tion about the population abundance and distribution of the Black-faced Spoonbill at all stages of its annual life cycle,and how these have changed during 2004-2020.Results:Black-faced Spoonbills mainly breed on the west coast of the Korean peninsula,while immature birds show a wider summer distribution throughout Yellow Sea coastal areas,when a few remain on wintering sites in the south.Combined tracking results and mid-winter counts confirmed known wintering sites on the east and south coasts of China,but showed that the species also winters on wetlands in the Yangtze River floodplain and in Southeast Asia.During 2004-2020,counts of wintering birds in coastal habitats increased from 1198 to 4864,with numbers wintering on the island of Taiwan contributing most to the overall increase.Latest counts found 5222 in 2021.We also identify key wintering and stopover sites as well as their current conservation status.Conclusions:This study revised the known summering and wintering ranges of the Black-faced Spoonbill and assessed the conservation status of key sites based on a combination of field survey and satellite tracking data.We recommend prioritisation of further field research to identify and survey inland wintering areas in the Yangtze River floodplain and summering areas of immature birds.More tracking of adult individuals and birds during spring migration is necessary to fill these information gaps.We also展开更多
Background:In the face of continued degradation and loss of wetlands in the Yangtze River floodplain(YRF),there is an urgent need to monitor the abundance and distribution of wintering waterbirds.To understand fully o...Background:In the face of continued degradation and loss of wetlands in the Yangtze River floodplain(YRF),there is an urgent need to monitor the abundance and distribution of wintering waterbirds.To understand fully observed annual changes,we need to monitor demographic rates to understand factors affecting global population size.Annual reproduction success contributes to dynamic changes in population size and age structure,so an assessment of the juvenile ratio(i.e.first winter birds as a proportion of total number aged)of overwintering waterbirds can be an important indicator of the reproductive success in the preceding breeding season.Methods:During 2016-2019,we sampled juvenile ratios among 10 key waterbird species from the wetlands in the YRF.Based on these data,we here attempt to establish a simple,efficient,focused and reliable juvenile ratio monitoring scheme,to assess consistently and accurately relative annual breeding success and its contribution to the age structure among these waterbird species.Results:We compared juvenile ratio data collected throughout the winter and found that the optimal time for undertaking these samples was in the early stages of arrival for migratory waterbirds reaching their wintering area(early to mid-December).We recommend counting consistently at key points(i.e.those where>1%biogeographical flyway population were counted)at sites of major flyway importance(Poyang Lake,East Dongting Lake,Shengjin Lake,Caizi Lake,Longgan Lake and Chen Lake).Based on this,the error rate of the programme(155 planned points,the count of 10 waterbird species is 826-8955)is less than 5%.Conclusions:We established a juvenile ratio monitoring programme for 10 key waterbird species in the wetlands of the YRF,and discuss the feasibility and necessity of implementing such a future programme,and how to use these data in our monitoring and understanding of the population dynamics of these waterbird populations.展开更多
Background:Evidence suggests that wintering waterbirds have become conspicuously more concentrated at two largest lakes of the Yangtze River Floodplain,East Dong Ting Lake(Hunan Province,29°20′N,113°E)and P...Background:Evidence suggests that wintering waterbirds have become conspicuously more concentrated at two largest lakes of the Yangtze River Floodplain,East Dong Ting Lake(Hunan Province,29°20′N,113°E)and Poyang Lake(Jiangxi Province,29°N,116°20′E),relative to other lakes,despite the establishment of reserves elsewhere.While this relationship is likely due to greater extent of undisturbed habitats in larger lakes,we understand little of the drivers affecting individual behaviours behind this tendency.Methods:We tracked wintering movements of three duck species(Eurasian Wigeon Mareca penelope,Falcated Duck M.falcata and Northern Pintail Anas acuta)using GPS transmitters,examining differences between the two largest lakes and other smaller lakes in ducks’habitat use,duration of stay at each lake and the daily distances moved by the tagged birds while at these sites.Results:The Eurasian Wigeon and Falcated Duck stayed five times longer and almost exclusively used natural habitat types at the two large lakes(91‒95%of positions)compared to length of stay time at smaller lakes,where they spent 28‒33 days on average(excluding the capture site)and exploited many more different habitats(including c.50%outside lakes).Conclusions:Our study is the first to show that shorter length of stay and more varied habitat use by ducks at small lakes may contribute to explaining the apparent regional concentration of numbers present of these and other species at the largest lakes in recent years.This compares with their declining abundance at smaller lakes,where habitat loss and degradation has been more manifest than on the larger lakes.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.41972194)the Study on the Origin of Chinese Civilization in Jiangsu Province。
文摘The middle and lower reaches of the Yangtze River,a primary region for freshwater lakes in China,have undergone significant transformations throughout the Holocene.These changes,driven by factors such as sea-level rise,climate change,and human activities,have led to the progressive elevation of water levels in this area.As a result,a floodplain has emerged,characterized by the formation of numerous shallow lakes along the river course.However,the pattern of water-level changes in the main channel of the Yangtze River during the Holocene remains unclear.This gap in knowledge poses challenges for understanding sediment transport dynamics,the interactions between the river and its adjacent lakes,and the prevention and control of flood disasters in the Yangtze River basin.To shed light on these issues,our study compiled data on the surface elevation and water depth of 81 lakes in the mid-lower reaches of the Yangtze River basin.Additionally,we analyzed historical water-level records from the 1900s to the 1970s at eight gauging stations from Shashi to Jiangyin along the river’s main stream.Our findings reveal that,particularly along the Jingjiang section,the basal elevation of most lakes is lower than the Yangtze River’s water level during the dry season.Conversely,the water level of the main stream exceeds that of both the floodplain and the lakes enclosed by the Jingjiang embankment.In the tidal reach,especially within the Taihu Lake basin,the basal elevation of lakes typically falls below sea level.Meanwhile,lakes located along the section from Chenglingji to Wuhu exhibit basal elevations that correspond with the Yangtze River’s annual average and dry season water levels.Given the widespread presence of lakes along the middle and lower reaches of the Yangtze River,our study introduces a new proxy for reconstructing the mean water level of the mid-lower Yangtze River in the Holocene.By analyzing sediments from Nanyi Lake and Chenyao Lake in the lower Yangtze River,we attempted to reconstruct the water level of
基金supported by the National Natural Science Foundation of China(Grant No.31870369 and 31970433)China Biodiversity Observation Networks(Sino BON)。
文摘Background:The Black-faced Spoonbill(Platalea minor)is a globally threatened species,nesting mainly in western Korea with smaller numbers breeding in Liaoning Province,China,and Far East Russia.Recent winter field surveys to estimate the species'population size were almost totally conducted in coastal areas,but tracking studies showed that some individuals now winter inland.To ensure its long-term survival,we need a more comprehensive assessment of the current distribution and abundance of the species.Methods:We combined the most recent count data and satellite tracking information to update existing informa-tion about the population abundance and distribution of the Black-faced Spoonbill at all stages of its annual life cycle,and how these have changed during 2004-2020.Results:Black-faced Spoonbills mainly breed on the west coast of the Korean peninsula,while immature birds show a wider summer distribution throughout Yellow Sea coastal areas,when a few remain on wintering sites in the south.Combined tracking results and mid-winter counts confirmed known wintering sites on the east and south coasts of China,but showed that the species also winters on wetlands in the Yangtze River floodplain and in Southeast Asia.During 2004-2020,counts of wintering birds in coastal habitats increased from 1198 to 4864,with numbers wintering on the island of Taiwan contributing most to the overall increase.Latest counts found 5222 in 2021.We also identify key wintering and stopover sites as well as their current conservation status.Conclusions:This study revised the known summering and wintering ranges of the Black-faced Spoonbill and assessed the conservation status of key sites based on a combination of field survey and satellite tracking data.We recommend prioritisation of further field research to identify and survey inland wintering areas in the Yangtze River floodplain and summering areas of immature birds.More tracking of adult individuals and birds during spring migration is necessary to fill these information gaps.We also
基金supported by the National Natural Science Foundation of China(Grant Nos.31870369,31970433)China Biodiversity Observation Networks(Sino BON)+1 种基金Innovative Research Group Project of the National Natural Science Foundation of China(CN)No.31670424。
文摘Background:In the face of continued degradation and loss of wetlands in the Yangtze River floodplain(YRF),there is an urgent need to monitor the abundance and distribution of wintering waterbirds.To understand fully observed annual changes,we need to monitor demographic rates to understand factors affecting global population size.Annual reproduction success contributes to dynamic changes in population size and age structure,so an assessment of the juvenile ratio(i.e.first winter birds as a proportion of total number aged)of overwintering waterbirds can be an important indicator of the reproductive success in the preceding breeding season.Methods:During 2016-2019,we sampled juvenile ratios among 10 key waterbird species from the wetlands in the YRF.Based on these data,we here attempt to establish a simple,efficient,focused and reliable juvenile ratio monitoring scheme,to assess consistently and accurately relative annual breeding success and its contribution to the age structure among these waterbird species.Results:We compared juvenile ratio data collected throughout the winter and found that the optimal time for undertaking these samples was in the early stages of arrival for migratory waterbirds reaching their wintering area(early to mid-December).We recommend counting consistently at key points(i.e.those where>1%biogeographical flyway population were counted)at sites of major flyway importance(Poyang Lake,East Dongting Lake,Shengjin Lake,Caizi Lake,Longgan Lake and Chen Lake).Based on this,the error rate of the programme(155 planned points,the count of 10 waterbird species is 826-8955)is less than 5%.Conclusions:We established a juvenile ratio monitoring programme for 10 key waterbird species in the wetlands of the YRF,and discuss the feasibility and necessity of implementing such a future programme,and how to use these data in our monitoring and understanding of the population dynamics of these waterbird populations.
基金supported by National Key Research and Development Program(2016YFC0500406)the National Natural Science Foundation of China(Grant Nos.31661143027,31670424,31870369)+1 种基金the Chinese Academy of Sciences Key Strategic Program,Water Ecological Security Assessment,the Major Research Strategy for Middle and Lower Yangtze River(Grant No.ZDRW-ZS-2017-3-3)China Biodiversity Observation Networks(Sino BON)
文摘Background:Evidence suggests that wintering waterbirds have become conspicuously more concentrated at two largest lakes of the Yangtze River Floodplain,East Dong Ting Lake(Hunan Province,29°20′N,113°E)and Poyang Lake(Jiangxi Province,29°N,116°20′E),relative to other lakes,despite the establishment of reserves elsewhere.While this relationship is likely due to greater extent of undisturbed habitats in larger lakes,we understand little of the drivers affecting individual behaviours behind this tendency.Methods:We tracked wintering movements of three duck species(Eurasian Wigeon Mareca penelope,Falcated Duck M.falcata and Northern Pintail Anas acuta)using GPS transmitters,examining differences between the two largest lakes and other smaller lakes in ducks’habitat use,duration of stay at each lake and the daily distances moved by the tagged birds while at these sites.Results:The Eurasian Wigeon and Falcated Duck stayed five times longer and almost exclusively used natural habitat types at the two large lakes(91‒95%of positions)compared to length of stay time at smaller lakes,where they spent 28‒33 days on average(excluding the capture site)and exploited many more different habitats(including c.50%outside lakes).Conclusions:Our study is the first to show that shorter length of stay and more varied habitat use by ducks at small lakes may contribute to explaining the apparent regional concentration of numbers present of these and other species at the largest lakes in recent years.This compares with their declining abundance at smaller lakes,where habitat loss and degradation has been more manifest than on the larger lakes.
