Indirect effects in a desert plant community: Is competition among annuals more intense under shrub canopies?

Katja Tielbörger*, Ronen Kadmon

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

59 Scopus citations


An unresolved discussion in contemporary ecology deals with the relative importance of competition along environmental gradients. In deserts, local-scale differences in environmental productivity, may be caused by the presence of shrubs, which represent a favorable habitat for annual populations within a nutrient-poor matrix. In this study, we attempted to test the hypothesis that facilitation of desert annuals by shrubs increase the intensity of competition among the annual plants. Such negative indirect effects have so far been ignored in studies about plant-plant interactions. We tested our hypothesis by measuring seedling survival and fecundity of four abundant annual plant species with and without neighbors in open areas and under shrub canopies in a sandy desert area. Our findings did not indicate indirect negative effects of shrubs on their understory annuals. Sensitivity to the presence of neighbors varied between species and surprisingly, the species with the smallest seeds was the only one which was not negatively affected by the presence of neighbors. In contrast to our hypothesis, there was no difference between the habitat types shrubs and openings in absolute and relative competition intensity. Our overall results suggest that negative indirect effects of shrubs are unimportant in determining demographic response of understory annual plants.

Original languageAmerican English
Pages (from-to)53-63
Number of pages11
JournalPlant Ecology
Issue number1-2
StatePublished - 2000

Bibliographical note

Funding Information:
We would like to thank Merav Katz for help in counting and weighing the seeds. M. Burkart, J. Heimann, T. Wiegand and two anonymous reviewers provided valuable comments on a previous version of this manuscript. The extraordinary support of I. and H. Künne is gratefully acknowledged. The research was funded by the MINERVA foundation, the Lady Davis Fellowship Trust, the Israel Academy of Sciences and Humanities and the German Ministry of Education, Research and Technology (BMBF). Fieldwork was conducted at the Nizzana research site of the Arid Ecosystems Research Center of the Hebrew University of Jerusalem and the MINERVA foundation.


  • Annual plants
  • Competition
  • Desert
  • Environmental gradients
  • Experiments
  • Facilitation
  • Indirect interactions
  • Sand dunes
  • Seed size
  • Shrubs


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