INVESTIGADORES
KITZBERGER Thomas
artículos
Título:
Facilitation vs, apparent competition: insect herbivory alters tree seedling recruitment under nurse shrubs in a steppewoodland ecotone
Autor/es:
CHANETON, E.J.; MAZÍA, C.N.; KITZBERGER, T.
Revista:
JOURNAL OF ECOLOGY (PRINT)
Editorial:
Blackwell
Referencias:
Año: 2010 vol. 98 p. 488 - 497
ISSN:
0022-0477
Resumen:
1. Facilitation of recruitment by nurse plants can play a major role in harsh environments. Yet the extent to which consumer-mediated apparent competition from habitat-forming plants may counteract facilitative interactions remains largely unexplored.2. We examined whether seedling predation by tenebrionid beetles seeking refuge under nurseshrubs may prevent tree recruitment facilitation in a Patagonian steppewoodland ecotone. Newly emerged seedlings of Austrocedrus chilensis were planted in shrub canopy, off-shrub shelter and bare soil microsites, and monitored for causes of early mortality and for overall survival under ambient and elevated beetle densities.3. Most seedlings in open microsites died from abiotic stress, whereas shrub cover and artificialshelters decreased desiccation mortality. Herbivory was the main cause of mortality in shrub microsites. Beetle addition increased predation beneath shrubs and in off-shrub shelters, indicating that apparent competition spilled over fromshrubs with high insect densities.4. Litter removal from shrubs prevented seedling predation suggesting that nurse plants alteredrecruitment by providing food as well as shelter to insects. Herbivory rates did not depend on seedling patch density but decreased with seedling age, with 1-week old plants being most vulnerable to beetle predation.5. Synthesis. Apparent competition from nurse plants can strongly reduce recruitment facilitationin stressful environments, although weak herbivore density dependence and seedling growth intoontogenetic refuges may limit the strength of apparent competition. An explicit consideration ofnegative, as well as positive, herbivore-mediated indirect effects from habitat-forming plants would broaden the understanding of community dynamics along stress gradients.