Co-ordinating Editor: Amy Symstad
Ontogenetic shifts in interactions of two dominant shrub species in a semi-arid coastal sand dune system
Article first published online: 31 MAR 2009
© 2009 International Association for Vegetation Science
Journal of Vegetation Science
Volume 20, Issue 3, pages 535–546, June 2009
How to Cite
Armas, C. and Pugnaire, F. I. (2009), Ontogenetic shifts in interactions of two dominant shrub species in a semi-arid coastal sand dune system. Journal of Vegetation Science, 20: 535–546. doi: 10.1111/j.1654-1103.2009.01055.x
- Issue published online: 20 MAY 2009
- Article first published online: 31 MAR 2009
- Received 5 August 2008;Accepted 12 December 2008.
- Nurse plants;
- Rooting depth;
- Water stress
Question: How does the interaction between two dominant shrub species in a coastal sand dune community change during their life history? Does this interaction influence their population dynamics?
Location: A semiarid coastal sand dune system in southeast Spain.
Methods: For 3 years we monitored physiological status, growth and reproductive effort of Juniperus phoenicea and Pistacia lentiscus, the dominant shrub species, growing either alone or in close spatial association. We also recorded adult mortality patterns and characterized seedling survival, soil properties and microclimate conditions beneath canopies and in bare ground.
Results and conclusions: There was a strong bi-directional interaction between the two studied species, with a net balance that changed in sign with increasing plant development. While mature individuals facilitated the establishment of seedlings of both species, adult mortality patterns suggested asymmetric competition at later life stages. The interaction with Pistacia negatively affected growth of juniper and contributed to its high mortality rates, while juniper had almost no effect on mature Pistacia individuals. Physiological data suggested that Pistacia had a competitive advantage over juniper, most likely because of differences in rooting patterns and tolerance to salinity, which may determine the source of water available for each species. Community dynamics are governed by facilitation at the seedling stage and shaped by differences in physiological traits in adult plants. Plant-plant interactions, which are strongly affected by environmental gradients, are important drivers of community dynamics in this system.