Quantifying beetle and bird diversity in a Mediterranean mountain agro-ecosystem

Abstract

In cultivated landscapes, the peculiar mosaic structure creates several types of habitat. Defining which habitats favor rich biodiversity is of increasing importance. Beetle and bird diversity was monitored in seven different habitats (cereals, corn, fallow, Robinia pseudoacacia plantations, grassland, cultivation-oak forest ecotone, and oak forest) in central Greece aiming at (a) quantifying the alpha and beta diversity using biotic indicators, (b) evaluating species richness, (c) identifying the most important habitats for beetle and bird species assemblages, and (d) examining species generalism or specialism in habitat use. To assess the impact of habitat type on biodiversity we estimated the abundance (A), species richness (S), the Shannon diversity index (H'), the Simpson dominance index (D), and the Shannon evenness index (E'). During the sampling period a total of 21,647 individuals of ground-dwelling beetles were captured in pitfall traps, classified into 63 species, while 21 bird species were recorded as breeders. The maximum beetle abundance and diversity was observed in grassland, fallow, and cereals. The highest breeding bird density and diversity were recorded in ecotone and oak forest, with the lowest ones in fallow. Cluster analysis demonstrated that the species assemblages were classified into two categories, open agricultural and closed wooded, while following the "IndVal" analysis a set of three species were identified as characteristic species of a specific habitat type. Our findings indicated that agro-ecosystems can enhance the faunal diversity of mountainous landscapes, while specific habitat types can significantly influence the species composition.