Wildfire extends the shelf life of elk nutritional resources regardless of fire severity

Abstract

Abstract Large‐scale, high‐severity wildfires are increasingly frequent across the western United States. Fire severity affects the amount of vegetation removed and helps dictate what, where, and how many plants regenerate postfire, potentially altering the available habitat and nutritional landscape for wildlife. To evaluate the effects of fire severity on summer nutritional resources for elk (Cervus canadensis), we collected field data and remotely sensed information in Years 2 and 3 after a large‐scale wildfire to compare forage quality and quantity across forest types and fire severities within the summer range of one elk population in west‐central Montana. To understand the landscape‐level effects of fire severity on nutritional resources, we developed predictive forage quality and quantity models. We used these models to predict nutritional resources across the landscape for four landscape scenarios representing different fire severity patterns (i.e., an unburned landscape, a landscape burned only at low severity, a landscape burned only at high severity, and the observed landscape burned at mixed severity). Shortly after the wildfire, summer forage quality and herbaceous forage quantity increased in both burned mesic and dry mixed‐conifer forests regardless of fire severity. Summer shrub forage quantity was greater in unburned mesic and dry forests, and there was no difference between fire severities in dry forests. Low‐severity burned mesic forests had significantly greater shrub forage quantity compared with high‐severity burned mesic forests. The three predicted burned landscape scenarios had the highest percentage of the summer range with adequate forage quality, which increased throughout the summer. By contrast, the predicted unburned landscape had the lowest percentage of summer range with adequate forage quality, which decreased throughout the summer. Wildfire extended the duration in which elk can access high‐quality forage in the summer in Years 2 and 3 postfire. Therefore, shortly after a large‐scale wildfire, elk may be better able to meet their nutritional requirements, which may positively impact elk body condition, reproductive performance, and survival.

Keywords

• Cervus canadensis
• forage quality
• forage quantity
• landscape nutrition model
• Montana
• summer