Group effects of a non‐native plant invasion on rodent abundance

Bryan M Kluever,Eric M Gese,Trinity N Smith

doi:10.1002/ecs2.2544

Bryan M Kluever, Eric M Gese + Show 1 more

Open Access

https://doi.org/10.1002/ecs2.2544

Copy DOI

Abstract

AbstractCheatgrass (Bromus tectorum) is the most prolific invading plant in western North America. Investigations determining the impact of this invasion on population state variables and community dynamics of rodents have largely occurred at the community or species level, creating a knowledge gap as to whether rodents affiliated by a shared taxonomy or other grouping are differentially affected by cheatgrass invasion. We examined rodent abundance along a gradient of cheatgrass cover using various groupings of two nocturnal rodent taxa comprising the majority of the rodent community in the Great Basin Desert. In the summers of 2010–2013, rodents were sampled and vegetation was measured on the U.S. Army Dugway Proving Ground in the Great Basin Desert of Utah, USA. We separately examined estimates of rodent abundance for all combined species within the Cricetidae and Heteromyidae families, the most numerically dominant species, and uncommon species pooled in relation to cheatgrass invasion severity. We detected an expected negative linear relationship between invasion severity and abundance for all cricetid groupings, including the most numerically dominant species, the deer mouse (Peromyscus maniculatus). Unexpectedly, heteromyid abundance exhibited an initial positive relationship, reached a threshold, and then exhibited a negative relationship, a phenomenon driven by Ord's kangaroo rats (Dipodomys ordii), the most numerically dominant species. We speculate this non‐linear finding was caused by a combination of trophic and non‐trophic pathways. Our findings provide new insight as to the potential for differential effects of cheatgrass on rodents in arid portions of the western United States. We suggest that future investigations on cheatgrass, and plant invader effects in general, consider parsing animal communities of interest by various taxonomic and/or ecological groupings rather than focusing exclusively on individual species or entire communities.

Highlights

Plant invasions have been identified as one of the greatest threats to ecological processes and functions (D’Antonio and Flory 2017)
Gaining a better understanding of the effects of plant invasions on fauna is paramount because invasions are expanding throughout many portions of the globe (Rai 2013), and there is a paucity of studies exploring this topic in relation to the number of communities, species, and landscapes potentially affected
An example of a non-trophic pathway was put forth by Ehlers Smith et al (2015) when they observed that despite mango orchards having greater vertical height structure than areas dominated by native plants, the absence of lowscrub woody cover in orchards caused an absence of avian species with life-history traits associated with this structural component

Summary

INTRODUCTION

Plant invasions have been identified as one of the greatest threats to ecological processes and functions (D’Antonio and Flory 2017). An example of a non-trophic pathway was put forth by Ehlers Smith et al (2015) when they observed that despite mango orchards having greater vertical height structure than areas dominated by native plants, the absence of lowscrub woody cover in orchards caused an absence of avian species with life-history traits associated with this structural component The impact to these pathways can depend largely on the physiological limitations, behavioral characteristics, and habitat requirements of the groups of animals being investigated (i.e., shared functional traits, and taxonomy or guild-based associations; French and Zubovic 1997). Because rodents often have significant effects on other trophic levels (e.g., primary producers and predators) and ecosystem processes (e.g., seed dispersal/consumption and soil disturbance), furthering our understanding of cheatgrass invasion, and invading plants in general, on rodent communities is needed to gain a more comprehensive understanding of ecosystem structure and function This could help prioritize native vegetation restoration efforts in the face of limited resources. We determined abundance of rodents and tested for cheatgrass effects for the two families comprising the rodent community, the most numerically dominant species from each rodent family, and across the less dominant species of each family

METHODS

RESULTS

DISCUSSION