The effects of habitat and competitive/facilitative interactions on reintroduction success of the endangered wetland herb, Arenaria paludicola


Establishing new populations is essential for preventing the extinction of critically endangered plant species. However, defining the range of environmental conditions suitable for the most severely endangered species is challenging, since few wild populations remain for study. Experimental reintroductions of these species can achieve multiple conservation goals by improving our understanding of habitat and management requirements while simultaneously establishing new populations. We demonstrate this with Arenaria paludicola, a critically endangered wetland plant species now known from a single wild population in coastal California. Before transplanting, we tested salinity tolerance in the greenhouse, and found tolerance of a broader range of soils than expected based on the current distribution. We then transplanted A. paludicola in three different habitat types, with and without neighbor removal. Success of A. paludicola transplants differed dramatically between the three habitat types, indicating the importance of variation at the habitat and microhabitat level. The best practices for transplant management are context-dependent: neighbor removal may promote the growth of A. paludicola, but neighbors may also facilitate transplant establishment in unstable substrates. After one year, A. paludicola continued to thrive in habitats dominated by Oenanthe sarmentosa with open canopies and moist soil. This habitat differs from that of the remaining wild population. Our discovery of an additional habitat type suitable for A. paludicola will allow more effective selection of future transplant sites.

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We would like to thank Connie Rutherford of the United States Fish and Wildlife Service, Tim Hyland of California State Parks, and Jim Velzy and Denise Polk from the University of California, Santa Cruz greenhouses, and Chris Muir for statistical advice. We also greatly appreciate the helpful comments of two anonymous reviewers. Funding was provided by the United States Fish and Wildlife Service.

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Correspondence to Megan Bontrager.

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The findings and conclusions in this publication are those of the authors and do not necessarily represent the views of the U.S. Fish and Wildlife Service.

Communicated by Philip Ladd.

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Bontrager, M., Webster, K., Elvin, M. et al. The effects of habitat and competitive/facilitative interactions on reintroduction success of the endangered wetland herb, Arenaria paludicola . Plant Ecol 215, 467–478 (2014).

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  • Indicator species
  • Endangered species
  • Marsh sandwort
  • Experimental transplant
  • Competition
  • Facilitation