Functional Redundancy in bird community decreases with riparian forest width reduction

Area of Science:

• Ecology
• Conservation Biology
• Biodiversity Research

Background:

• Riparian ecosystems face anthropogenic threats, reducing biodiversity and ecosystem services.
• The relationship between species composition and ecosystem function in fragmented landscapes is uncertain.
• Habitat loss and disturbance impact the functional diversity of ecological communities.

Purpose of the Study:

• Assess the impact of riparian forest width reduction and vegetation disturbance on Functional Diversity (FD) components: Functional Redundancy (FRed), Functional Evenness (FEve), and Functional Richness (FRic).
• Identify potential thresholds in these relationships and determine which bird diet guilds (frugivores, insectivores, omnivores) are most affected.
• Evaluate the ecological implications for riparian bird assemblages.

Main Methods:

• Quantified the response of FD components to varying riparian forest widths and vegetation disturbance levels.
• Analyzed nonlinear relationships and identified critical thresholds for FD metrics.
• Examined the sensitivity of different bird diet guilds to habitat fragmentation and disturbance.

Main Results:

• Functional Redundancy (FRed) was linearly reduced in riparian forests narrower than 400m.
• Functional Evenness (FEve) was linearly increased with vegetation disturbance exceeding 60%.
• Declines in insectivore and frugivore richness were observed in highly disturbed riparian forests.

Conclusions:

• Riparian bird communities exhibit negative impacts on FD with reduced forest width (<400m) or increased disturbance (>60%).
• These critical thresholds exceed current Brazilian legal minimums for riparian forest width.
• Conservation strategies must prioritize expanding riparian habitats and mitigating disturbance to maintain functional diversity.