Land use changes around the wetland and diversity of waterfowl and shorebirds in Anzali, Almagol, Alagol, and Ajigol international wetlands (Iran)

Anzali, Ajigol, Almagol and Alagol international wetlands are important global ecosystems. In this study, the trend of land use changes in these wetlands and its impacts on the distribution of waterfowl and shorebirds. One of the common methods in studying the ecosystem changes of wetlands is the diversity evaluation of waterfowl and shorebirds. Because of the ease of observing birds in nature, it is possible to find any possible changes in the wetlands by continuously studying the species diversity, population changes, and the habitat quality.

Satellite images and field information of wetlands and their land changes were prepared based on available data and field surveys. In order to prepare the vegetation map based on the wetland index, 6 bands of Landsat satellite TM sensor were used to calculate the NVIDA index. Also, using field survey and sampling of plants and wetland index, the predominance of plants in the region was determined. Then, land-use maps in different periods of 20 years (1998-2019) were prepared based on satellite image processing and image classification using the maximum likelihood method. The data obtained during 8 years census and field surveys, the Shannon-Wiener species diversity indices and inversely the Simpson index, Margalf and Manhink indices has been calculated and were used to determine the species richness and Pilo and Simson indices were used to determine the species evenness.

The results showed that the water area in Alagol, Ajigol and Almagol international wetlands has decreased by 1050.8 hectares (53.7%) and in Anzali wetland by 1541 hectares (18.9%). According to the results, in Alagol, Ajigol and Almagol international wetlands, the most changes are related to vegetation of medium density with 273% increase and in Anzali wetland, the most changes are related to increase in herbaceous plants with 270.3%. According to Margalf species richness index, the highest species richness was observed in Abchelikian. Also, the highest species diversity was observed in the genus Murghabian based on Shannon-Wiener index and the reverse of Simpson index. Also, the highest amount of species evennessbased on Pilo index and Simpson index was observed in the Baklanian genus.

The water extent of the wetlands has generally decreased and due to the increase of man-made land uses in the margins of the wetlands, adverse effects on the wetland ecosystem have been caused to vulnerability of wetlands to degradation. As a result of declining water levels in wetlands and the uncontrolled growth of non-native plants and the reduction of dissolved oxygen, the rate of habitat destruction of migratory aquatic animals and birds will increase. Due to the declining trend in biodiversity indicators in recent years as a result of declining water levels and land-use change, increasing the ecological protection of the wetland through management projects such as habitat protection, poaching control and pollution control, is recommended.