Abstract Detail

Ecology

Alba, Christina [1], DePrenger-Levin, Michelle [2].

Title: Land management in an increasingly complex world: The interaction of fire and herbicide use in natural areas.

Given that fires are burning more often across the western US, it is important to understand how fire interacts with different land management practices. In particular, herbicide spraying can alter propagule availability, thereby shaping plant community assembly after fire. We sampled plant communities following the 2020 Calwood Fire in Boulder County, CO, to explore how pre-fire herbicide treatments including Rejuvra® shaped plant community response to fire. Given Rejuvra®’s pre-emergence control of short-lived grasses and forbs, we assessed post-fire response of target (Bromus tectorum, Bromus japonicus, and short-lived non-native forbs) and potential non-target (short-lived native grasses and forbs) species in sprayed and unsprayed areas that were burned or not. Bromus tectorum and B. japonicus were well controlled in burned (96% lower cover of both species where sprayed) and unburned (93% lower cover of B. tectorum; 83% lower cover of B. japonicus) areas. Non-native short-lived forbs were also well controlled in both burned (richness, 55% lower in sprayed areas; cover, 63% lower in sprayed areas) and unburned (richness, 43% lower; cover, 58% lower) areas. Two native annual grasses, Vulpia octoflora and Hordeum pusillum, were too uncommon to assess. For short-lived native forbs, richness was 75% lower in burned areas that had been sprayed than those that had not. Conversely, in the absence of fire, spraying had little effect on short-lived native forb richness, and the non-target effect on richness did not emerge for percent cover. In line with previous work, long-lived native forbs and grasses had higher percent cover in sprayed than unsprayed areas, and we show that this holds regardless of burn status.

1 - Denver Botanic Gardens, Research & Conservation, 909 York Street, Denver, CO, 80206, United States
2 - 909 York Street, Denver, CO, 80206, United States

Keywords:
wildfire
Herbicide
community assembly
Cheatgrass.

Presentation Type: Oral Paper
Number: EC02001
Abstract ID:317
Candidate for Awards:None