# Fire Is Associated With Positive Shifts in Bumble Bee ( Bombus vosnesenskii ) Body Size and Bee Abundance in the Southern Sierra Nevada Mountains

## TL;DR

Wildfires in the Southern Sierra Mountains are linked to increased bumble bee abundance and larger body size, possibly due to changes in floral resources.

## Contribution

This study reveals that wildfires can benefit bumble bees by increasing their size and abundance in the Southern Sierra Mountains.

## Key findings

- Bumble bee workers in burned areas were larger in size.
- Wildfires were associated with increased bumble bee abundance.
- Burned areas had unique floral communities, though not necessarily more abundant or diverse.

## Abstract

Climate change is increasing the frequency and severity of wildfires worldwide. Although wildfires are typically viewed as destructive, emerging research suggests they may have benefits for some species, including some pollinators. One reason for this is that wildfires can increase floral resource availability in the years immediately following the burn, potentially creating more favorable conditions for pollinator foraging and reproduction. In this study, we focused on how the 2021 KNP Complex Fire impacted the bumble bee
Bombus vosnesenskii
in the Southern Sierra Mountains, where the effects of fire on this pollinator species have not been previously explored. Consistent with bumble bee studies in other areas, we found an increase in the size of
B. vosnesenskii
workers in recently burned areas. This effect was detectable despite a limited number of sampling events and locations in our study, and irrespective of the habitat type (meadow vs. forest) in which sampling occurred. We failed to detect increased floral resource availability (abundance or diversity) in burned areas but did observe unique floral communities in burned areas. Our findings contribute to our growing understanding of fire's impact on pollinators and support the broad idea that fire might have benefits for some organisms.

Wildfires increase the abundance and size of bumble bees in the Southern Sierra Mountains. Wildfires may benefit bumble bees by enhancing floral resource availability and increasing their populations.