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Expanding the invasion footprint: Ventenata dubia and relationships to wildfire, environment, and plant communities in the Blue Mountains of the Inland Northwest, USAAuthor(s): Claire M. Tortorelli; Meg A. Krawchuk; Becky K. Kerns
Source: Applied Vegetation Science. 49(2): 683-696.
Publication Series: Scientific Journal (JRNL)
Station: Pacific Northwest Research Station
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DescriptionQuestions: A recently introduced non-native annual grass, Ventenata dubia, is challenging previous conceptions of community resistance in forest mosaic communities in the Inland Northwest. However, little is known of the drivers and potential ecological impacts of this rapidly expanding species. Here we (1) identify abiotic and biotic habitat characteristics associated with the V. dubia invasion and examine how these differ between V. dubia and other problematic non-native annual grasses, Bromus tectorum and Taeniatherum caput-medusae; and (2) determine how burning influences relationships between V. dubia and plant community composition and structure to address potential impacts on Inland Northwest forest mosaic communities.
Location: Blue Mountains of the Inland Northwest, USA.
Methods: We measured environmental and plant community characteristics in 110 recently burned and nearby unburned plots. Plots were stratified to capture a range of V. dubia cover, elevations, biophysical classes, and fire severities. We investigated relationships between V. dubia, wildfire, environmental, and plant community characteristics using non-metric multidimensional scaling and linear regressions.
Results: Ventenata dubia was most abundant in sparsely vegetated, basalt-derived rocky scablands interspersed throughout the forested landscape. Plant communities most heavily invaded by V. dubia were largely uninvaded by other non-native annual grasses. Ventenata dubia was abundant in both unburned and burned areas, but negative relationships between V. dubia cover and community diversity were stronger in burned plots, where keystone sagebrush species were largely absent after fire.
Conclusions: Ventenata dubia is expanding the overall invasion footprint into previously uninvaded communities. Burning may exacerbate negative relationships between V. dubia and species richness, evenness, and functional diversity, including in communities that historically rarely burned. Understanding the drivers and impacts of the V. dubia invasion and recognizing how these differ from other annual grass invasions may provide insight into mechanisms of community invasibility, grass-fire feedbacks, and aid the development of species-specific management plans.
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CitationTortorelli, Claire M.; Krawchuk, Meg A.; Kerns, Becky K. 2020. Expanding the invasion footprint: Ventenata dubia and relationships to wildfire, environment, and plant communities in the Blue Mountains of the Inland Northwest, USA. Applied Vegetation Science. 49(2): 683-696. https://doi.org/10.1111/avsc.12511.
KeywordsAnnual grass, Bromus tectorum, forest, grass-fire cycle, Inland Northwest, invasive species, non-native plants, scabland.
- The effects of precipitation and soil type on three invasive annual grasses in the western United States
- Historical fire and Ventenata dubia invasion in a temperate grassland
- Vegetation change over seven years in the largest protected Pacific Northwest Bunchgrass Prairie remnant
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