Aspen Bibliography

Title

An Invasive Grass and Litter Impact Tree Encroachment Into a Native Grassland

Document Type

Article

Author ORCID Identifier

Margarete A. Dettlaff https://orcid.org/0000-0001-9533-4350

Nadir Erbilgin https://orcid.org/0000-0001-9912-8095

James F. Cahill Jr. https://orcid.org/0000-0002-4110-1516

Journal/Book Title/Conference

Applied Vegetation Science

Volume

24

Issue

4

Publisher

Wiley-Blackwell Publishing, Inc.

First Page

1

Last Page

12

Publication Date

10-15-2021

Abstract

Questions

Woody plant encroachment and invasive plants are two critical factors that negatively impact grass-dominated ecosystems. While studies have extensively investigated these factors individually, research on how invasive species impact the susceptibility of grasslands to encroachment is less common. Using the aspen parkland, an endangered savannah-type ecosystem, we asked how the presence of a widespread invasive grass in North America, smooth brome (Bromus inermis), impacted the growth and survival of one-year old trembling aspen (Populus tremuloides) seedlings. We also asked if plant litter was a potential mechanism of inhibition (as has been proposed for brome litter) or coexistence (as has been hypothesized for aspen litter) in this system.

Location

Alberta, Canada.

Methods

We used a manipulative experimental approach to determine if the survival and subsequent growth of planted aspen seedlings was impacted by the presence of smooth brome and manipulation of litter amount and type.

Results

We found that the presence of smooth brome reduced aspen survival by 57% compared to uninvaded habitats, likely mediated by reduced soil moisture, while litter manipulation had no effect on survival. For surviving seedlings, local context had complex impacts on growth; the addition of aspen litter to brome-invaded communities increased seedling growth while aspen litter additions to native communities resulted in decreased growth.

Conclusion

These results suggest that invasion by smooth brome will alter the dynamics of aspen establishment in this system, potentially leading to significant changes to this already endangered landscape. Though smooth brome may serve as a barrier to aspen establishment, accumulation of aspen litter from nearby stands to brome patches could lead to faster growth of seedlings in invaded areas at the edge of existing aspen stands. Our results also suggest more generally that the impact of invasive plants on the establishment of native woody plants can be dependent on litter inputs.

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