Butterfly edge effects are predicted by a simple model in a complex landscape.

Area of Science:

• Ecology
• Landscape Ecology
• Conservation Biology

Background:

• Organismal responses to habitat fragmentation and landscape structure are crucial for ecological understanding.
• A lack of a unifying conceptual framework has hindered interpretation of edge effect research.
• Edge effects are critical in understanding habitat fragmentation impacts.

Purpose of the Study:

• To test a general edge effects model predicting organismal responses to habitat edges.
• To evaluate if life history traits and resource availability explain edge responses.
• To assess the predictive power of an edge effects model in a complex landscape.

Main Methods:

• Tested an edge effects model using observations of 15 butterfly species across 12 edge types.
• Collected data over 3 years in a desert riparian landscape.
• Compared observed edge responses with model predictions for 211 species/edge combinations.

Main Results:

• Observed edge responses matched model predictions significantly more than by chance.
• 70% of predicted positive or negative edge responses were observed.
• Habitat preference and resource complementarity were supported as key mechanisms driving edge effects.

Conclusions:

• A general edge effects model, considering life history and resources, can explain many organismal responses to habitat edges.
• Resource-based mechanisms are key drivers of edge effects.
• Predicting and understanding edge responses in complex landscapes is feasible with basic ecological knowledge.