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Avian diversity changes in traditional agricultural landscapes of Japan over ten years

Morelli, Federico1; Benedetti, Yanina1; Svitok, Marek2; Fujita, Taku3; Ueta, Mutsuyuki4; Katayama, Naoki5

Published Apr 03, 2025 on Dryad. https://doi.org/10.5061/dryad.02v6wwqf4

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Apr 03, 2025 version files 575.44 KB

Abstract

Agricultural intensification is a leading cause of biodiversity loss worldwide. However, the traditional agroecosystems are often associated with high avian diversity because of their landscape heterogeneity offering available niches to different bird species. Here, we focused on the temporal changes in taxonomic, functional, and phylogenetic diversity of avian communities from Satoyama traditional agricultural landscapes of Japan. We found significant temporal trends (e.g., increasing) in overall species richness, forest specialist species richness, phylogenetic diversity and phylogenetic relatedness within avian assemblages, regardless of the land use composition surrounding the sites. The simultaneous increase in species richness and phylogenetic relatedness could highlight a process of biotic homogenization, typical of anthropized environments. Avian diversity was also significantly affected by the proportion of water bodies (e.g., increasing functional richness and dispersion, but decreasing functional evenness or redundancy) and other land use types (e.g., a negative association between species richness and the proportion of fields). The proportion of paddy fields affected each type of bird richness differently: inverse u-shape for forest generalists, negative for forest specialists species, and positive for open land specialists. When assessing the temporal stability of bird community composition, we found that such stability was significantly correlated to the proportion of grasslands, waterbodies and urban landscapes. Specifically, avian communities surrounded by grasslands were characterized by higher species replacement over time. Additionally, very low or very high proportions of urban landscapes were associated with a relative instability of bird community composition. Our findings support the hypothesis that traditional farming systems represent valuable landscapes supporting avian diversity. However, the relative composition of land use types plays a crucial role in shaping different components of taxonomic, functional and phylogenetic diversity in bird assemblages, as well as their temporal stability.