Industrial rice farming supports fewer waterbirds than traditional farming on Chongming Island, China

Abstract

Natural wetlands in coastal areas have been reclaimed in China and other regions of Asia. The reclaimed lands have been used for large-scale industrial farming, replacing traditional farming methods, especially in rice fields. To understand the impact of land-use conversion on biodiversity, particularly of coastal migratory waterbirds, we selected two study sites in Chongming Island, China, representing traditional rice fields versus industrial rice farms. At each site, we 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 waterbird populations. Over two annual cycles (from August 2013 to May 2015), 39 waterbird species were observed, with a mean density of 29.3 AE 5.4/ha, on traditional rice fields, compared with 16 species with a mean density of 2.8 AE 0.4/ha on large-scale industrial rice farms. Our results demonstrated that waterbird diversity was higher on traditional rice fields than on industrial rice farms. Analyses of habitat characteristics and waterbird populations showed that traditional rice fields had more preferred habitats for waterbirds, such as more open-water cover areas, lower bare mud cover areas, lower rice plant density, no concrete-covered areas and flooding in the winter. The results suggested that the replacement of traditional rice fields with large-scale industrial rice farms has had a significantly negative impact on migratory waterbirds using the East Asian-Australasian Flyway; such a change could also have detrimental effects on waterbird conservation efforts in China and other countries along this important migration route.

Effect of wind farms on wintering ducks at an important wintering ground in China along the East Asian–Australasian Flyway

“…These results were in accord with the satellite tracking outcomes during the day. There was frequent human activity in the aquaculture ponds and paddy fields at Chongming Dongtan during the day, including agricultural activities (Xie et al., 2019) and motorized vehicles, which could have a negative effect on duck abundance. In contrast, artificial brackish marsh, as a restoring wetland, offered stable water levels and low human activity (Kuang et al., 2019), potentially making it a better wintering habitat for ducks.…”

“…To guarantee that all the ducks were counted, all quadrats were surveyed along the dykes, roads, or paddies. Each quadrat was scanned for at least 10 min, with no maximum time limit for completing a count; however, the counts were completed as rapidly as possible to avoid double counting birds (Xie, Zhang, Li, Ma, & Wang, 2019). All ducks were identified to species level, and all individuals in the survey area were counted.…”

Risk evaluation of onshore wind farms in relation to wild duck (Anatidae) movements in the Yangtze River Mouth, China

“…The positions of the eyes on the head determine the duck's wide visual range, indicating their ability to detect and tolerate wind farms during flights [57]. In addition, extensive farmland and aquaculture ponds with highquality food resources provide good foraging grounds for ducks in winter on the East China coast [17,41], and may orient a spatial memory for ducks. Ducks may learn as a result of continuous exposure to the presence of wind turbines in an area over time, resulting in functional habitat loss, or reduced risk perception and increased habituation [53].…”

“…The main habitat types in this area were mudflats, brackish marsh, paddy fields, and aquaculture ponds [38]. Brackish marsh was distributed outside the dyke and provided roosting habitats for waterbirds, and large areas of paddy fields and aquaculture ponds distributed inland of, and close to, the dyke provided foraging habitats [40,41]. Wintering ducks carried out local movements between the brackish marsh and paddy fields/aquaculture ponds across the dyke, which was partially populated by wind turbines (Figure 2a) [17].…”