Facilitation and interference underlying the association between the woody invaders Pyracantha angustifolia and Ligustrum lucidum

TECCO, PAULA ANDREA; DÍAZ, SANDRA; GURVICH, DIEGO EZEQUIEL; PÉREZ HARGUINDEGUY, NATALIA; CABIDO, MARCELO; BERTONE, GUSTAVO ALEJANDRO

APPLIED VEGETATION SCIENCE

Año: 2006 vol. 10 p. 211 - 218

1402-2001

Questions: 1. Is there any post-dispersal positive effect of the exotic shrub Pyracantha angustifolia on the success of1. Is there any post-dispersal positive effect of the exotic shrub Pyracantha angustifolia on the success of Ligustrum lucidum seedlings, as compared to the effect of the native Condalia montana or the open herbaceous patches between shrubs? 2. Is the possible facilitation by Pyracantha and/or Condalia related to differential emergence, growth, or survival of Ligustrum seedlings under their canopies? Location: Córdoba, central Argentina.seedlings, as compared to the effect of the native Condalia montana or the open herbaceous patches between shrubs? 2. Is the possible facilitation by Pyracantha and/or Condalia related to differential emergence, growth, or survival of Ligustrum seedlings under their canopies? Location: Córdoba, central Argentina.Pyracantha and/or Condalia related to differential emergence, growth, or survival of Ligustrum seedlings under their canopies? Location: Córdoba, central Argentina.Ligustrum seedlings under their canopies? Location: Córdoba, central Argentina. Methods: We designed three treatments, in which ten mature individuals of Pyracantha, ten of the dominant native shrubWe designed three treatments, in which ten mature individuals of Pyracantha, ten of the dominant native shrub Condalia montana, and ten patches without shrub cover were involved. In each treatment we planted seeds and saplings ofand ten patches without shrub cover were involved. In each treatment we planted seeds and saplings of Ligustrum collected from nearby natural populations. Seedlings emerging from the planted seeds were harvested after one year to measure growth. Survival of the transplanted saplings was recorded every two month during a year. Half of the planted seeds and transplanted saplings were cage-protected from rodents.collected from nearby natural populations. Seedlings emerging from the planted seeds were harvested after one year to measure growth. Survival of the transplanted saplings was recorded every two month during a year. Half of the planted seeds and transplanted saplings were cage-protected from rodents. Results: Ligustrum seedling emergence did not differ among treatments while growth was significantly higher in the absence of shrub cover. Sapling survival was significantly higher under the canopy of Pyracantha, intermediate underLigustrum seedling emergence did not differ among treatments while growth was significantly higher in the absence of shrub cover. Sapling survival was significantly higher under the canopy of Pyracantha, intermediate underPyracantha, intermediate under Condalia, and lowest in the absence of shrub cover. Caging did not affect growth but enhanced seedling emergence and sapling survival. Conclusion: The differential sapling survival in the shrub canopy treatments is consistent with natural sapling distribution.and lowest in the absence of shrub cover. Caging did not affect growth but enhanced seedling emergence and sapling survival. Conclusion: The differential sapling survival in the shrub canopy treatments is consistent with natural sapling distribution.Conclusion: The differential sapling survival in the shrub canopy treatments is consistent with natural sapling distribution. Pyracantha and, less so, Condalia, has a nurse-plant effect on Ligustrum. This results from contrasting effects of the shrubs on different stages of the life cycle of Ligustrum: no effect on seedling emergence, negative on seedling growth, and positive on sapling survival. This suggests that efforts to control the expansion of Ligustrum over the landscape should tackleand, less so, Condalia, has a nurse-plant effect on Ligustrum. This results from contrasting effects of the shrubs on different stages of the life cycle of Ligustrum: no effect on seedling emergence, negative on seedling growth, and positive on sapling survival. This suggests that efforts to control the expansion of Ligustrum over the landscape should tackleLigustrum: no effect on seedling emergence, negative on seedling growth, and positive on sapling survival. This suggests that efforts to control the expansion of Ligustrum over the landscape should tackleLigustrum over the landscape should tackle Pyracantha as well. as well.