Life on the edge: reproductive mode and rate of invasive Phragmites australis patch expansion
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The dynamics of plant invasions from initial colonization through patch expansion are driven in part by mode of reproduction, i.e., sexual (seed) and asexual (clonal fragments and expansion) means. Expansion of existing patches—both rate and mode of spread into a matrix of varying conditions—is important for predicting potential invader impacts. In this study, we used fine-scale genetic assessments and remote sensing to describe both the rate and mode of expansion for 20 Phragmites australis patches in flooded and unflooded wetland units on the Great Salt Lake, UT. We found that the majority of Phragmites patch expansion occurred via clonal spread but we also documented instances of (potentially episodic) seedling recruitment. The mode of patch expansion, inferred from patch edge genet richness, was unrelated to flooding in the wetland unit in the preceding growing season. The rate of Phragmites patch expansion varied from 0.09 to 0.35 year−1 and was unrelated to the mode of spread. In six patches monitored across two years, monoclonal patches stayed monoclonal, whereas patches with higher genet richness had a marked increase in diversity in the second year. The findings of the present study suggest how this partially clonal species can exploit the benefits of both sexual (i.e., genetic recombination, widespread dispersal, colonization of new areas) and asexual reproduction (i.e., stability of established clones suited to local environmental conditions) to become one of the most successful wetland plant invaders. To control this species, both forms of reproduction need to be fully addressed through targeted management actions.
KeywordsClonality Common reed Genetic diversity Genet richness Invasive species Seedling recruitment Sexual reproduction
We thank Shannon Clemens Syrstad and Omar Alminagorta for assistance with the map production, and Rebekah Downard and Ben Crabb for their help with leaf collection. We also thank Dr. Austin Jensen and the crew of the AggieAir Flying Circus Service Center at the Utah Water Research Laboratory for their work in acquiring the high-resolution aerial imagery used in this research. Funding was provided by the U.S. Geological Survey (104(b) Program).
- Altartouri A, Nurminen L, Jolma A (2014) Modeling the role of the close-range effect and environmental variables in the occurrence and spread of Phragmites australis in four sites on the Finnish coast of the Gulf of Finland and the Archipelago Sea. Ecol Evol 4:987–1005CrossRefPubMedPubMedCentralGoogle Scholar
- Jensen JR (2005) Introductory digital image processing: A remote sensing perspective. Pearson Education Inc, Upper Saddle RiverGoogle Scholar
- Olson B, Lindsey K, Hirschboeck V (2004) Habitat management plan: Bear River Migratory Bird Refuge, Brigham City, Utah. US Department of the Interior Fish and Wildlife Service, Brigham CityGoogle Scholar
- Tipping ME (2001) Sparse Bayesian learning and the relevance vector machine. J Mach Learn Research 1:211–244Google Scholar
- Warren RS, Fell PE, Grimsby JL, Buck EL, Rilling GC, Fertik RA (2001) Rates, patterns, and impacts of Phragmites australis expansion and effects of experimental Phragmites control on vegetation, macroinvertebrates, and fish within tidelands of the lower Connecticut River. Estuaries 24:90–107CrossRefGoogle Scholar
- Welsh L, Endter-Wada J, Downard R, Kettenring K (2013) Developing adaptive capacity to droughts: the rationality of locality. Ecol Soc 18:7Google Scholar
- Wilson EO, Bossert WH (1971) A primer of population biology. Sinauer Associates, SunderlandGoogle Scholar