Folia Geobotanica

, Volume 41, Issue 1, pp 95–106

Demographic response to shading and defoliation in two woodland orchids

Article

DOI: 10.1007/BF02805264

Cite this article as:
Shefferson, R.P., Kull, T. & Tali, K. Folia Geobot (2006) 41: 95. doi:10.1007/BF02805264

Abstract

Many woodland herbs are long-lived, clonal geophytes that have evolved life histories favoring survival over reproduction. We examined the life history responses of natural populations of two woodland orchid species,Cypripedium calceolus andCephalanthera longifolia to defoliation and heavy shading conducted early in the growing seasons of 2002 and 2003. We asked whether, in view of the importance of growth for the survival of geophytes, treated plants were more likely to exhibit reduced flowering than reduced vegetative growth in the seasons following treatment. We also asked whether plants would suffer reduced ramet performance. Both treatments led to significant declines in flower number per ramet, number of leaves per ramet, and mean ramet height relative to controls inCypripedium. However, inCephalanthera, only shaded plants exhibited significant declines in flower number per ramet, and only defoliated plants exhibited declines in mean ramet height. The number of ramets per plant did not decline relative to controls in either species. Thus, these orchids, especiallyCypripedium, appeared to allocate resources preferentially to vegetative growth functions over sexual reproduction. Per-plant variation in leaf and flower number per ramet, as well as in mean ramet height, consistently declined in response to treatment, significantly so in the case of mean ramet height, suggesting that ramets became more similar within genets. These results suggest both similarities and differences in the ways in whichCephalanthera andCypripedium mobilize resources in response to stress.

Keywords

Cephalanthera longifolia Cypripedium calceolus Geophytes Life history trade-offs Perennials Orchidaceae Resource allocation 

Nomenclature

Tutin T.G. et al. (1968–1993) 

Copyright information

© Institute of Botany, Academy of Sciences of the Czech Republic 2006

Authors and Affiliations

  1. 1.Department of Integrative Biology, 3060 VLSB #3140University of CaliforniaBerkeleyUSA
  2. 2.Forestry and Forest Products Research InstituteTsukubaJapan
  3. 3.Institute of Zoology and BotanyEstonian Agricultural UniversityTartuEstonia

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