, Volume 175, Issue 4, pp 1277–1290 | Cite as

Shrubs as ecosystem engineers across an environmental gradient: effects on species richness and exotic plant invasion

  • Andrew R. Kleinhesselink
  • Susan M. Magnoli
  • J. Hall Cushman
Community ecology - Original research


Ecosystem-engineering plants modify the physical environment and can increase species diversity and exotic species invasion. At the individual level, the effects of ecosystem engineers on other plants often become more positive in stressful environments. In this study, we investigated whether the community-level effects of ecosystem engineers also become stronger in more stressful environments. Using comparative and experimental approaches, we assessed the ability of a native shrub (Ericameria ericoides) to act as an ecosystem engineer across a stress gradient in a coastal dune in northern California, USA. We found increased coarse organic matter and lower wind speeds within shrub patches. Growth of a dominant invasive grass (Bromus diandrus) was facilitated both by aboveground shrub biomass and by growing in soil taken from shrub patches. Experimental removal of shrubs negatively affected species most associated with shrubs and positively affected species most often found outside of shrubs. Counter to the stress-gradient hypothesis, the effects of shrubs on the physical environment and individual plant growth did not increase across the established stress gradient at this site. At the community level, shrub patches increased beta diversity, and contained greater rarified richness and exotic plant cover than shrub-free patches. Shrub effects on rarified richness increased with environmental stress, but effects on exotic cover and beta diversity did not. Our study provides evidence for the community-level effects of shrubs as ecosystem engineers in this system, but shows that these effects do not necessarily become stronger in more stressful environments.


Coastal dunes Ecosystem engineers Exotic species Facilitation Stress-gradient hypothesis 



We are grateful to the following individuals for assistance in the field: Drew Carlson, Nicole Christie, Rayma Cooley, Kara Doolin, Krista Lindley, Devin Moorad, Stephanie Parreira, Avi Starr-Glass, and Woody Wu. Jackie Sones of the UC Davis Bodega Marine Reserve provided valuable logistical support. Janis Boettinger provided advice on soil analyses and performed organic carbon analysis. Peter Adler, Chengjin Chu, Caroline Christian, Susan Harrison, David Pyke, and two anonymous reviewers provided comments on the manuscript and/or study design. Research support was provided by grants from the California Native Plant Society, Northern California Botanists, Sigma Xi Grants-in-Aid of Research Program, Sonoma State University, and the National Science Foundation (DEB-9981663 to J.H.C.).

Supplementary material

442_2014_2972_MOESM1_ESM.pdf (1.5 mb)
Supplementary material 1 (PDF 1485 kb)


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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Andrew R. Kleinhesselink
    • 1
    • 4
  • Susan M. Magnoli
    • 2
    • 3
    • 4
  • J. Hall Cushman
    • 4
  1. 1.Department of Wildland ResourcesUtah State UniversityLoganUSA
  2. 2.W.K. Kellogg Biological StationMichigan State UniversityHickory CornersUSA
  3. 3.Department of Plant BiologyMichigan State UniversityEast LansingUSA
  4. 4.Department of BiologySonoma State UniversityRohnert ParkUSA

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