Trends of Changes in Waterbird Biodiversity Indices of the Bakhtegan Basin Wetlands Using Semi-wintering Census: 1988-2018

Bakhtegan wetland including Kamjan, Tashk and Bakhtegan are the most important aquatic habitats of waterbirds in the inland of Iran that in recent years, the severe decline in water level and habitat changes have reduced the quality and quantity of habitat for waterbirds. In this study, the trends of biodiversity changes are studied based on the values of waterbird species diversity indices (Shannon-Wiener & Simpson), Species richness indices (Margalef & Minhinick) and species evenness indices (Pielou & Simpson) using the SDR-IV software in the 31 years' period (2018-1998) including two ten-years and one 11-years' time frames.Moreover, the area of alive wetland in the migration season of waterbirds by calculated using the Landsat satellite imagery collected on November to December. Comparison of diversity indices using ANOVA (analysis of variance) at three time intervals showed that there is no significant difference between species diversity indices and Pielou species evenness index (F2,28 = Shannon-Wiener 2.082, Simpson 0.995, Pielou 2.132, P>0.05). The lowest values of the Margalef index were found in the period of 2009–2009 that were significantly different with other previous decade but there was no significantly differences with periods of 1988–1998. The highest value of the richness index of Minhinick and Simpson E were found in the periods of 2009–2019 and were significantly different with previous decades (p < 0.05). The highest of area of alive wetland in the 1990s and the lowest was in 2001 and in the last decade. It seems that fluctuation of water level and decreasing the alive area of Bakhtegan basin wetlands are the most important factors in the changing the values of waterbird diversity. Providing the environmental flow requirement, implementation of comprehensive wetland management programs and establishment of integrated ecosystem management system are the most important strategies for restoring the waterbird biodiversity of the studied wetlands.