The Efficiency of Indices of Richness, Evenness and Biodiversity in the Investigation of Species Diversity Changes (Case Study: Migratory Water Birds of Parishan International Wetland, Fars Province, Iran)

Wetlands are among the world’s most productive environments and one of their best known functions is to provide a habitat for migratory aquatic birds.1‒3 Wetlands are important habitats that these birds use them for wintering, resting, shelter, and they are also used as a source of drinking water, feeding, and social interactions. On the other hand, wetlands are strongly influenced by human impacts, because they are located where people live, such as nutrient-rich soils for agriculture and silviculture. Human activities can degrade or even destroy wetland habitats, and the health and livelihood of migratory aquatic birds are put at risk.4‒6 Despite the increase in wetland conservation efforts over the past three decades,1,7 substantial losses of wetlands continue. It is not surprising then that many waterbird populations in different parts of the world remain in long-term and considerable decline, since wetland loss and degradation continue to be the main cause for these population changes, probably now being exacerbated by severe and prolonged droughts and other impacts of climate change. All these circumstances determine habitat selection by migrant birds and habitat loss hence is the major threat to them and habitat protection is the most important means of conserving their biodiversity. In Zagros landscapes located in the western Iran, wetlands, as in other dry lands, represent a broad variety of natural resources with environmental, social, and scientific values and play an important role in the maintenance of biological diversity. Despite their great intrinsic values, these ecosystems are suffering a severe pressure caused by human demands for water, agricultural production and habitation leading to the disappearance of many of them. Migratory waterbirds depend on suitable wetlands and migration success depends on intact migratory routes with the availability of certain key food resources and resting opportunities at these sites. We believe that they are susceptible to changes happened to wetlands and it might affect their habitat preferences for wintering.8,9 Being more vulnerable to environmental changes, migratory waterfowls can be a robust bioindicator of wetlands status. These biodiversity indicators are quantifiable environmental factors10 that can show how the circumstances vary and help assess the suitable environment for migrating birds induced by human impacts. Responses of migrant waterbirds to the characteristics of natural wetlands influence their richness and diversity. We therefore suggested long-term monitoring of their biodiversity to discover how internationally concerned wetlands have been degraded and what are the consequences of this degradation on migratory birds. One basic approach to quantify biodiversity is to apply the predefined measures i.e. richness, evenness and diversity.11‒14 Estimating these indices, there are some common methods i.e. Simpson, Camargo and Smith & Wilson in evenness and Shannon-Wiener, Brillouin and Simpson in biodiversity.3,14,15 It is believed that each one of the mentioned criteria may provide meaningful understanding of the wetland’s biodiversity changes. The integration of biodiversity monitoring is an essential step in the assessment of the wetland’s conditions.