Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

Cooperative and Competitive Interactions in the Recruitment of Marsh Elders

Mark D. Bertness and Su Ming Yeh
Ecology
Vol. 75, No. 8 (Dec., 1994), pp. 2416-2429
Published by: Wiley
DOI: 10.2307/1940895
Stable URL: http://www.jstor.org/stable/1940895
Page Count: 14
  • Download ($42.00)
  • Subscribe ($19.50)
  • Cite this Item
Cooperative and Competitive Interactions in the Recruitment of Marsh Elders
Preview not available

Abstract

While most studies of plant recruitment focus on competitive interactions, recruitment can be influenced by both positive and negative interactions. We studied recruitment in the marsh elder, Iva frutescens, to examine the relationship between positive and negative forces in recruitment. Marsh elder seedling establishment was competitively precluded in undisturbed habitats by the dense perennial turfs that dominate marsh habitats. Adult marsh elders, however, passively trapped tidally transported plant debris that kills underlying vegetation. As a result, adult Iva created bare space and positively influenced seedling recruitment by facilitating the formation of seedling safe sites. Within bare patches, Iva seedling survivorship was high under adult conspecifics and at high seedling densities. In contrast, solitary Iva seedlings without adult neighbors suffered extremely high mortality. These positive associations among neighbors were experimentally shown to result from neighbor buffering of hypersaline soil conditions. Salinities in unshaded bare patches were elevated due to increased exposure to radiation and surface evaporation. Both adult nurse plants and high seedling densities shaded the soil, ameliorated high soil salinities, and thus had positive effects on seedling performance. Under adult canopies or when soil salinities were experimentally reduced by shading or watering, positive associations did not occur and all interactions among seedlings or between seedlings and adults were competitive. Our results indicate that marsh plant recruitment is dictated by a balance between positive and negative forces. Moreover, since positive interactions were only seen once densities and physical forces had been experimentally manipulated, our results when that positive interactions may be important forces in assemblages even where they are not conspicuous. These findings contribute to growing evidence that positive interactions, particularly those mediated by neighbor amelioration of harsh physical conditions, are important community level processes in a wide range of plant and animal assemblages.

Page Thumbnails

  • Thumbnail: Page 
2416
    2416
  • Thumbnail: Page 
2417
    2417
  • Thumbnail: Page 
2418
    2418
  • Thumbnail: Page 
2419
    2419
  • Thumbnail: Page 
2420
    2420
  • Thumbnail: Page 
2421
    2421
  • Thumbnail: Page 
2422
    2422
  • Thumbnail: Page 
2423
    2423
  • Thumbnail: Page 
2424
    2424
  • Thumbnail: Page 
2425
    2425
  • Thumbnail: Page 
2426
    2426
  • Thumbnail: Page 
2427
    2427
  • Thumbnail: Page 
2428
    2428
  • Thumbnail: Page 
2429
    2429