| Chongming Dongtan Wetland is the largest and the most developed estuarine tidal wetland in the Yangtze River estuary.It has abundant wetland resources and unique hydrological conditions for rivers and seas,and provided a good habitat for birds.It's an important stopover site for migratory birds in the East Asia-Australasia Flyway,which has a high ecological service function value and plays an irreplaceable role in the protection of bird diversity.In recent years,due to the invasion and removal of Spartina alterniflora,the migration of migratory birds has been greatly affected,and the ecological service functions and values of the protected areas have changed.This paper briefly describes the plant community,benthic and fish community structure in Dongtan wetland,collects one-year bird observation data,studies the preference of waterfowl for the natural wetland and artificial wetland of restoration,and analyzes the relationship between the trends of bird populations' the changes and the Social and economic development of Chongming County(district)by Adopting 11 years of banding birds data.In addition,it evaluated the value of maintaining biodiversity and other ecological service functions in the Dongtan Wetland.The main findings are as follows:(1)At the beginning of wetland restoration,the number of bird observations in a single line of artificially repaired wetland is not much different from that of natural wetlands,but the composition of the species is very different from that of natural wetlands.The observations show that from November 2013 to October 2014,the bird observations in the Dongtan Nature Reserve recorded a total of 84,225 water birds,belonging to 8 orders,13 families and 74 species,with a diversity index of 2.09 and a uniformity index of 0.49.70,441 birds were observed in the natural wetland area,belonging to 7 orders,11 families and 56 species,with an average of 17,610 observations per sample line,a diversity index of 1.73,and a uniformity index of 0.43.In the artificial wetland of restoration,13,784 birds were observed,belonging to7 orders,10 families and 57 species,with a diversity index of 2.59 and a uniformity index of0.64.The species co-occurrence of avian community in the two type wetlands is 0.36.Throughout the year,the diversity index and evenness index of natural wetland were lower than that of artificial wetland of restoration.There were significant difference between two type wetland in the avian diversity index and evenness index,the quantity and species quantity of Charadriiformes birds and the species quantity of Anseriformes birds,and no significant difference in the avian quantity,species quantity and the quantity of Anseriformes.In the natural wetland,the quantity of Charadriiformes is the largest and accounted for 62.92%.In the artificial restored wetland,the quantity of Anseriformes is the largest and accounted for 50.20%.During the migration,the changes in quantity of Anseriformes were significantly and positively correlated between the two type wetlands,but there were no relationships for Charadriiformes.There were significantly positive intraspecific and interspecific crossing correlations in the change of 2 type duck quantity in the two type wetlands.However,no relationships were found for the quantity of waders and egrets.The artificial wetland of restoration in Chongming Dongtan National Nature Reserve provides a good habitat for a variety of migrated birds,especially for Anseriformes,although the Charadriiformes prefer to perching natural wetlands.Therefore,it is important to not only protect the undamaged natural wetlands from the influence of external factors but also carry out the artificial wetland restoration project.(2)The number of banding birds showed a downward trend,and its species,diversity and evenness did not change significantly.During this period,3 orders(Charadriiformes,Ciconiiformes and lariformes)8 families and 53 species birds were banded from 2005 to 2015 in Dongtan Wetland.The quantity of banding birds species changed between 32 species and 45 species every year.The diversity index of banding bird was between 2.79 and 2.38,and the evenness index was between 0.68 and 0.76 in ten years.Average daily Banding bird quantity trended decrease,which change from 59.07 to 17.13 in ten years.Inter-specific correlation analysis for 10 shorebird populations who were banded more than 1% of the total number of the birds found that 9 pairs of shorebirds were correlated and 1 pairs were significantly positively correlated,which contained Calidris tenuirostris?C.alpina?C.ruficollis and so on.(3)Changes in the environment and socio-economic development in Chongming District have an impact on the population changes of the banding birds.The main factor causing the change of the number of birds is the comprehensive factor of Chongming's social and economic development In facts of environment,the correlation analysis showed that the number of banding bird was significantly positively correlated with the area of Scirpus mariqueter,fish number and fish species number.There was a negative correlation between bird species and precipitation.There were negative correlation between diversity index,evenness index and average temperature as well.Factor analysis shows that 13 environmental factors can be summarized as four factors: foraging space,vegetation,benthic animals and temperature,and there is no obvious trend of environmental comprehensive factors.The analysis of time series vector autoregressive model shows that the environmental comprehensive factor has a strong influence on the number of birds.Benthic factors are the main influencing factor for the changes in the number and species of the banding birds,and it is the main driving force for the changes in bird communities.In terms of socio-economic development,the correlation analysis showed that 15 of the 22 indicators of industrial and agricultural output value in Chongming County(district)were negatively correlated with the number of banding birds in Dongtan wetland in 11 years,and no relationship with the species,diversity index and uniformity index.Factor analysis shows that 22 indicators can be summarized into four major factors: economy,quality,survival,and industrialization,and the scores of comprehensive factors are on the rise.The analysis of time series vector autoregressive model shows that the main factor causing the change of the number of birds is the comprehensive factor of Chongming's social and economic development,considering only the two variables of the banding bird community itself and the Chongming socio-economic comprehensive factor.The natural succession of bird populations has less impact on the number of changes in their own population.(4)The Contingent Valuation Method was used to evaluate the biodiversity value of Chongming Dongtan wetland.A questionnaire of payment card CVM was developed for the survey study.The biodiversity value of Chongming Dongtan wetland is RMB 116.9 billion per year.We sent out the questionnaires to 490 respondents,and received 462 usable responses.Data analysis reveals that the willingness to pay of the biodiversity Dongtan wetland is RMB 58.3 per year.The results showed that age,occupation and travel propensity were extremely closely correlated with WTP,educational level,familiar degree of Dongtan Wetland were closely correlated with WTP,sexual distinction,domicile,income level were not correlated with WTP.The sexual distinction,educational level and Travel times in recent three years were extremely correlated with the WTP value,Age,occupation,familiar degree to Dongtan Wetland and domicile were not correlated with WTP value. |
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