Little evidence for local adaptation to soils or microclimate in the post-fire recruitment of three Californian shrubs

Abstract

Background: Seedling recruitment following fire is an infrequent yet critical demographic transition for woody plants in Mediterranean ecosystems.

Aims: Here we examine whether post-fire seedling recruitment of three widespread Californian chaparral shrubs is affected by local adaptation within an edaphically and topographically complex landscape.

Methods: We reciprocally transplanted 6-month-old seedlings of Adenostema fasciculatum, Ceanothus cuneatus and Eriodictyon californicum to serpentine and sandstone soils, and cool northerly and warm southerly slopes.

Results: At the age of 2 years, none of the species manifested higher survival or growth on ‘home’ compared with ‘away’ soils or slopes, indicating an absence of local adaptation with respect to seedling recruitment in these environments. Seedlings of all species manifested lower survival and relative growth on serpentine soils regardless of seedling source, as well as a variety of other destination and source effects.

Conclusions: The ability of these three species to recruit in new environments, such as in restoration settings or in response to shifting climates, is unlikely to be impeded by a need for seeds from sources that closely match their edaphic or topographic destination.

Keywords:

• chaparral
• ecotypic differentiation
• fire
• local adaptation
• reciprocal transplant
• seedling recruitment
• serpentine
• topography

Acknowledgements

We thank B. Anacker, B. Going, D. Schmidt, E. Dietrich, H. Safford, J. Celis, J. Vieto, N. Dondoyano, N. Pope, S. Woolhouse, and Y. Thorne for their help in the field. We thank B. Anacker, B. Going, F. Altermatt, J. Wright and three anonymous reviewers for useful comments on earlier versions of this manuscript. We also thank Paul Aigner and the McLaughlin UC Natural Reserve for providing the long-term weather data. This work was supported by National Science Foundation DEB-0939403 to N. Rajakaruna.

Additional information

Notes on contributors

Annette Bieger

Annette Bieger is a project manager and she is interested in processes that affect plant diversity and the spread of invasive species.

Nishanta Rajakaruna

Nishanta Rajakaruna is a professor and his research focuses on the factors and mechanisms driving plant speciation and community assembly on serpentine and other edaphically harsh environments.

Susan Harrison

Susan Harrison is a professor and she studies the processes that shape and maintain plant species diversity at the landscape scale, where small-scale forces such as competition and facilitation interact with large-scale forces such as niche evolution and dispersal.