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As climate changes, Alaska’s boreal forest faces the simultaneous threats of increasing invasive plant abundances and increasing area burned by wildfire. Highly flammable and widespread black spruce forest represents a boreal habitat that may be increasingly susceptible to non-native plant invasion. Research Objective:Assess the susceptibility of burned black spruce forests to non-native plant invasions in Interior Alaska
Key Questions:
• Do burn severity, soil moisture and burn age of black spruce sites influence the likelihood of non-native plant establishment?
• What is the relative importance of regional scale factors vs. site-level factors in determining vulnerability to invasion?
• What cross-taxa trends can be used to help inform invasive plant management decisions in burned boreal forest?
Method:
- Non-native plant field survey of 100 burned field sites in three regions of interior Alaska that spanned a gradient of burn severities, moisture levels, and
burn ages.
- Surveyed adjacent roadsides of all sites to gauge non-native plant propagule pressure.
- Collected soil cores with intact surface vegetation from 12 sites burned in 2004, and 6 sites from a chronosequence of older burn sites for a greenhouse
experiment.
- In the Greenhouse, I sowed invasive Melilotus alba, Hieracium aurantiacum, and Bromus inermis ssp. inermis seeds on the soil core surfaces.
- Assessed invasive plant germination, growth, reproduction and final biomass in the greenhouse.
Results:
I found that invasive focal species Melilotus alba, Hieracium aurantiacum, and Bromus inermis ssp. inermis grew better in soil from low severity burns and burns between 10 and 20 years old than in soil from high severity or recent burns. In addition, regional differences between burn complexes outweighed burn severity or burn age in determining the invasibility of burned black spruce sites. In both recent and older burns, re-establishing native ground cover vegetation appeared to offer burned areas a level of resistance to invasive plant establishment. I concluded that burned black spruce areas are susceptible to non-native plant invasions and some burn types or region may be more vulnerable to invasion than others. Managers of natural lands should monitor burned areas with nearby non-native plant populations to reduce the potential of spread into Alaska’s boreal forest.
Publications:
Spellman, K.V., C. P. H. Mulder, and T. N. Hollingsworth. 2014. Wildfire burn susceptibility to non-native plant invasions in black spruce forests of interior Alaska. Biological Invasions DOI 10.1007/s10530-013-0633-6 [PDF]
Villano, K. L., 2008. Wildfire burn susceptibility to non-native plant invasions in black spruce forests of interior Alaska. Master’s Thesis. University of Alaska, Fairbanks, AK. [PDF]
Villano, K. L., and C. P. H. Mulder. 2008. Invasive plant spread in burned lands of interior Alaska. Final report for National Park Service—Alaska Region and National Aeronautics and Space Administration. Fairbanks, AK. 25 pp. [PDF]
Collaborators: Dr. Christa P.H. Mulder, Dr. Theresa Hollingsworth
Funding: Center for Global Change and Arctic System Research, Center for Invasive Plant Management, Arctic Audubon Society
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