Human-Induced Landscape Changes Homogenize Atlantic Forest Bird Assemblages through Nested Species Loss

Area of Science:

• Ecology
• Conservation Biology
• Biodiversity Research

Background:

• Citizen science data is increasingly used for ecological assessments, especially in biodiversity-rich regions like the Neotropics.
• Terrestrial ecosystems face significant changes due to human activities, potentially impacting species composition and diversity.
• Understanding taxonomic homogenization is crucial for effective conservation strategies in altered landscapes.

Purpose of the Study:

• To investigate taxonomic homogenization in terrestrial birds across a gradient of human-altered landscapes (HAL) in the South Brazilian Atlantic Forest.
• To identify species associated with taxonomic homogenization in response to landscape changes.
• To assess the role of beta diversity, turnover, and nestedness in avian community shifts.

Main Methods:

• Analysis of bird data from 87 citizen science sites across natural, rural, and urban landscapes.
• Assessment of regional-scale taxonomic homogenization by comparing beta diversity among different HALs.
• Accounting for geographical distance and zoogeographical affinities using georeferencing and phytogeographical domain analysis.
• Calculation of beta diversity using multivariate dispersion and analysis of compositional changes (turnover and nestedness).
• Identification of characteristic species for each landscape type using indicator species analysis.

Main Results:

• A significant decrease in beta diversity was observed with increasing landscape alteration, indicating bird homogenization.
• Rural sites exhibited half the beta diversity of natural habitats, while urban sites showed less than 10% of the natural habitat beta diversity.
• Turnover was key in differentiating sites based on HAL and phytogeography, while nestedness highlighted directional species loss across HALs and phytogeographical domains.
• Native generalists and non-native urban specialists were identified as characteristic species in rural and urban environments.

Conclusions:

• Strong evidence supports taxonomic homogenization in the South Brazilian Atlantic Forest avian communities.
• Homogenization results from directional and nested species loss, leading to simplified ecosystems.
• The study highlights the vulnerability of Neotropical biodiversity to landscape alteration and the need for targeted conservation efforts.