Construction Technology Of Rice Fields For Waterbird Conservation And Evaluation Of Its Effect

Globally,migratory waterbirds are facing serious threats.Decline of waterbird population is widespread among the nine major flyways of the world.East Asian-Australasian Flyway?EAAF?is one of the world's most important shorebirds flyways,which starts from the winter sites in Australia and New Zealand,pasts the coastline in China and other regions of Southeast Asia and East Asia,and finally gets to the breed sites in Siberia and Alaska.Higher number and proportion of waterbirds are globally threatened in the EAAF than in any of the other major flyways of the world.Observed rates of waterbird species decline in the EAAF are among the highest ones of any major flyways on the planet.The possible mechanisms are the destruction of waterbird habitat or coastal reclamation,but further studies are needed to explore other potential causes.China's coastal wetlands support abundant biodiversity and provide the foundation for regional economy.Migrating waterbirds refuel on these stopovers along the East Asian-Australian Flyway.Reclamation of coastal wetlands are accelerating in China,which contributes to the loss of China's coastal wetlands.Some of the reclamation areas have been converted to rice fields.Rice cultivation can provide important wetland habitats for waterbird under proper management.Rice-Fish Culture System is an agro-ecological system that integrates growing fish in flooded rice fields.China boasts a history of 1700 years in rice-fish-farming practice.Recently,most of reclamation wetlands have been converted to industrial rice farms with large-scale mechanized planting and rice monoculture.This transfer from traditional to industrial patterns of rice farming widely exists in coastal areas of China and other regions of Southeast Asia and East Asia in the EAAF.Does the transfer from traditional to industrial patterns of rice farming impact migratory waterbird abundance in reclaimed coastal areas?We carried out the study to answer these questions.This study was based on a major scientific research projects of Shanghai Science and Technology Commission,in order to restore the damaged wetlands and optimize waterbird habitats.We put forward a new construction technology of rice fields for waterbird conservation,and explored the key technology and technical system of waterbird conservation,to enhance the value of waterbird conservation in rice fields.We studied the effects of waterbird conservation in rice fields in Chongming Dongtan from autumn 2012 to spring 2016,lasting for three and a half years.Results of this study are as follows:1.Construction technology of rice fields for waterbird conservationWe conducted the construction of rice fields for waterbird conservation in Chongming Dongtan from autumn 2012 to summer 2013.We constructed drainage systems,soil tillage,rice cultivation,and succeeded in the 5^th rice planting trial.We put forward a new construction technology of rice fields for waterbird conservation,to meet the need of rice cultivation and waterbird habitat requirement,and applied for a patent of invention.The key content of the structure is to set up a pond unit with open water areas in the rice field,and construct ecological islands in the pond unit.Integrate growing fish in the pond to form an agro-ecological system.The structure of rice paddy unit occupies an area of 0.5-1ha,includes a rice plant area,a pond unit and drainage systems.The drainage systems of rice paddy unit is connected with other units.2.Impacts of the construction technology of rice fields on waterbird conservationTo understand the impacts of such technology on waterbird biodiversity,we selected two study sites in Chongming Dongtan,China,representing experimental rice fields according to the construction technology versus industrial rice farms.At each site,we chose 10 ha study area,and carried out waterbird population surveys over one annual cycle?from August 2013 to May 2014?.A total of 34 waterbird species were recorded with a density of 41.87±6.62/ha in the experimental rice fields,while a total of 12 waterbird species were recorded with a density of 2.08±0.45/ha in the industrial rice farms during the study.Both parameters were significantly higher in experimental rice fields than in industrial rice fields?p<0.001?.Our results demonstrated that there were significant differences in species richness and waterbird density between the two rice farms of different management strategy.3.Transfer from traditional to industrial patterns of rice farming impacts migratory waterbird abundance in reclaimed coastal areasTo understand the impacts of such management pattern transformation on waterbird biodiversity,we selected two study sites in Chongming Dongtan,China,representing traditional rice fields versus industrial rice farms.At each site,we selected3 study quadrat with a total area of 2.5 ha,and carried out waterbird population surveys,measured the environmental factors hypothesized to be important in determining waterbird abundance,and analyzed the effects of the different farming patterns on the waterbird populations.Over two annual cycles?from August 2014 to May 2016?,a total of 43 waterbird species and 2,405 individuals were recorded.A total of 39 waterbird species and 2,197individuals with a density of 29.29±3.64/ha were recorded in the traditional rice fields during the study.A total of 16 waterbird species and 208 individuals with a density of2.77±0.28/ha were recorded on industrial rice farms during the study.Our results demonstrated that there were significant differences in species richness and waterbird density between the two patterns of rice farming,with both parameters significantly higher in the traditional rice fields?n=90,both p<0.001?.Most of waterbirds in traditional rice fields were Charadriidae?50.25%?and Anatidae?43.38%?.On industrial rice farms,most of waterbirds were Ardeidae?44.71%?,followed by Others?32.21%?and Charadriidae?21.63%?.RDA analysis of the effects of habitat characteristics on waterbird populations showed that traditional rice fields had more preferred habitats for waterbirds,such as higher water cover,lower rice plant density,no concrete surface,and flooding in the winter.The results suggested that waterbird density overall in particular were strongly and positively correlated with open-water cover and water level,whereas were negatively correlated with concrete cover,rice planting density,rice cover,and bare mud cover.Anatidae density was strongly and positively correlated with open-water cover and water level,whereas was negatively correlated with bare mud cover.The results of this study suggestted that the replacement of traditional rice farms with large-scale industrial rice farms would have had significant negative impacts on migratory waterbirds of the East Asian-Australasian Flyway.Such a change is also likely to have had,and be having,a detrimental effect on waterbird conservation efforts in this and other countries along the East Asian-Australasian Flyway.Significance of the study are as follows:1.We put forward a new explanation for the decline of waterbird of the East Asian-Australasian Flyway:the replacement of traditional rice farms with large-scale industrial rice farms would have had significant negative impacts on migratory waterbirds of the East Asian-Australasian Flyway.2.We carried out waterbird population surveys,showed that industrial rice farms reduced the value of waterbird conservation in rice fields.Managements of rice fields were essential for waterbird conservation.3.We put forward a new construction technology of rice fields for waterbird conservation,which benefits rice cultivation and waterbird as well.We provided a case study for the restoration of damaged wetlands and the optimization of waterbird habitats.4.The study proposed a new way to enhance the value of waterbird conservation in rice fields by ecological engineering,which combined ecology theory,research,and application practice,providing abundant data for waterbird conservation around the world.