title: Species-specificity of nurse plants for the establishment, survivorship, and growth of a columnar cactus.
abstract: OBJECTIVE
  Seedling establishment and early survivorship are crucial steps for the regeneration of plant populations because both have long-lasting effects on plant population dynamics. For species recruiting through facilitation, species-specific facilitative effects might affect early fitness, an overlooked aspect in studies of facilitation considering groups of nurse species. •
  
  
  METHODS
  We experimentally evaluated the roles of 10 nurse species and open space on the early performance of the columnar cactus Neobuxbaumia mezcalaensis. We measured establishment, survivorship, and growth of individuals over 3 years. Moreover, to study an extended period of the ontogeny of the interaction between this cactus and its nurse plants, we also monitored survivorship and growth rates of individuals between 3 to 12 cm tall during a 3-year period. •
  
  
  RESULTS
  Neobuxbaumia mezcalaensis performance varied significantly among nurse species, and only six yielded positive effects on early fitness. Densely canopied plants were the best nurses for this cactus. However, even among densely canopied species, some produced negative effects on the early fitness of N. mezcalaensis, indicating that similar nurse plants may elicit either facilitative or interference effects on beneficiary species. •
  
  
  CONCLUSIONS
  Our results emphasize the importance of species-specific facilitative interactions in the crucial early stages in the life cycle of N. mezcalaensis and how different nurse species modify the effect of seed-rain and contribute significantly to the population dynamics of the species.
authors: Instituto de Ecología, Departamento de Ecología de la Biodiversidad, Universidad Nacional Autónoma de México, Apartado Postal 70-275, México 04510 D.F., Mexico.
authors: Juan Pablo Castillo
authors: JP
authors: Landero
authors: Alfonso
authors: A
authors: Valiente-Banuet