, Volume 7, Issue 4, pp 341–357

Effects of Local Deforestation on the Diversity and Structure of Southern California Giant Kelp Forest Food Webs

Special Feature

DOI: 10.1007/s10021-003-0245-6

Cite this article as:
Graham, M. Ecosystems (2004) 7: 341. doi:10.1007/s10021-003-0245-6


It has been hypothesized that the high diversity of giant kelp forests is due primarily to the provision of energy and habitat by the giant kelp (Macrocystis pyrifera). In this article, I use a 19-year-long kelp forest-monitoring data set from the Channel Islands National Park (a) to identify associations between subtidal species and forested or deforested habitats, (b) to generate an idealized food web for Southern California giant kelp forests in order to identify the primary conduits of energy flow through the system, and (c) to determine changes in the diversity and complexity of this food web due to localized giant kelp deforestation. A total of 275 common species were observed in the park between 1982 and 2000, of which 36% occurred significantly more often in kelp-forested areas than in deforested areas (that is, sea urchin barrens); 25 species were found exclusively in forested areas. Most of these associations were clearly identified as trophic and/or structural associations with giant kelp itself. The producer level of the food web was diverse, although giant kelp apparently represents the greatest single source of fixed carbon through either direct grazing or the production of phytodetritus. Primary, secondary and tertiary consumer levels were also represented by numerous species, and generalist consumers were common. With deforestation, the source of primary production shifts from primarily kelps to ephemeral microalgae, macroalgae, and phytoplankton. These results support the reliance of giant kelp forest food-web structure and diversity on the presence of the forest itself.


giant kelp Macrocystis pyrifera kelp forests deforestation sea urchin barrens habitat association food web foundation species 

Copyright information

© Springer-Verlag New York, Inc. 2004

Authors and Affiliations

  1. 1.Center for Population BiologyUniversity of California, Davis, California 95616USA
  2. 2.Current address: Moss Landing Marine LabsB272 Moss Landing Road, Moss Landing, California 95039USA

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