Prescribed Fire Effects on Hummingbird Taxonomic and Functional Diversity in Pine–Oak Forests in West-Central Mexico

Abstract

Prescribed fires are a management strategy involving the controlled application of fire to achieve specific ecological objectives. In the pine–oak forests in west-central Mexico, we conducted an experimental low-severity prescribed fire to assess its effects on hummingbird diversity. We hypothesized that low-severity prescribed fire would enhance both taxonomic and functional diversity by modifying understory vegetation structure and increasing floral resource availability. To test this, we performed point count censuses in both low-severity prescribed fire and fire-suppressed sites where wildfire had been excluded for over 40 years. Taxonomic diversity was assessed using Hill numbers to estimate true diversity across different abundance weights, while functional diversity was evaluated through indices such as functional richness, functional evenness, and functional divergence. Our results indicated that low-severity prescribed fires did not affect overall hummingbird diversity as both low-severity prescribed fire sites and fire-suppressed sites exhibited comparable species richness. However, sites with low-severity prescribed fire and concave summits showed a significantly higher abundance of common and highly abundant species. Notably, species richness did not align with functional richness, as the fire-suppressed site exhibited the highest functional diversity. These findings suggest that hummingbird community structure is influenced by a combination of fire history, topography, vegetation structure, and floral resource availability. We recommend maintaining a heterogeneous forest matrix, incorporating patches with fire suppression, and areas subjected to prescribed fires of varying severity. This multifaceted approach enhances both taxonomic and functional biodiversity, promoting habitat heterogeneity and ensuring the persistence of diverse hummingbird assemblages in fire-prone ecosystems.