Biotic resistance and disturbance: rodent consumers regulate post-fire plant invasions and increase plant community diversity

Biotic resistance and disturbance are fundamental processes influencing plant invasion outcomes; however, the role of consumers in regulating the establishment and spread of plant invaders and how disturbance modifies biotic resistance by consumers is unclear. We document that fire in combination wi...

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Bibliographic Details
Published in:Ecology (Durham) 2016-07, Vol.97 (7), p.1700-1711
Main Authors: St. Clair, Samuel B., O'Connor, Rory, Gill, Richard, McMillan, Brock
Format: Article
Language:English
Subjects:
Biodiversity
Bromus tectorum
cheatgrass
Community ecology
competition
deserts
fire
Grasses
Great Basin
halogeton
Nonnative species
Plant resistance
Predation
Rodents
small mammals
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Summary:Biotic resistance and disturbance are fundamental processes influencing plant invasion outcomes; however, the role of consumers in regulating the establishment and spread of plant invaders and how disturbance modifies biotic resistance by consumers is unclear. We document that fire in combination with experimental exclusion of rodent consumers shifted a native desert shrubland to a low-diversity, invasive annual grassland dominated by Bromus tectorum (cheatgrass). In contrast, burned plots with rodents present suppressed invasion by cheatgrass and developed into a more diverse forb community. Rodents created strong biotic resistance to the establishment of aggressive plant invaders likely through seed and seedling prédation, which had cascading effects on plant competition and plant community diversity. Fire mediated its positive effects on plant invaders through native plant removal and by decreasing the abundance and diversity of the rodent community. The experimental disruption of plant and consumer-mediated biotic resistance of plant invaders using fire and rodent exclusion treatments provides strong evidence that native plants and rodents are important regulators of plant invasion dynamics and plant biodiversity in our study system. While rodents conferred strong resistance to invasion in our study system, fluctuations in rodent populations due to disturbance and climatic events may provide windows of opportunity for exotic plant species to escape biotic resistance by rodent consumers and initiate invasions.
ISSN:0012-9658
1939-9170
DOI:10.1002/ecy.1391