Interspecific competition changes reproductive output but does not increase reproductive costs in a grassland perennial

• Published in: Basic and applied ecology 2009-09, Vol.10 (6), p.525-534
• Main Authors: Dostál, Petr, Havlíčková, Vendula, Jorritsma-Wienk, Linda D., Eriksson, Ove, Herben, Tomáš
• Format: Article
• Language: English
• Subjects: Agrostis capillaris; belowground biomass; Biologi; Biology; Clonal growth; clonal variation; colonizing ability; community ecology; deadheading; Grasslands; growth traits; habitats; interspecific competition; life history; Life-history functions; NATURAL SCIENCES; NATURVETENSKAP; Phenotypic plasticity; phenotypic variation; plant competition; Plant Ecology; plant growth; reproductive traits; seed development; sexual reproduction; Succession; Succisa; Succisa pratensis; Terrestrial ecology; Terrestrial, freshwater and marine ecology; Terrestrisk ekologi; Terrestrisk, limnisk och marin ekologi; Trade-offs; vegetative growth; växtekologi
• ISSN: 1439-1791; 1618-0089
• DOI: 10.1016/j.baae.2008.12.004

In plants, it is hypothesized that allocation trade-offs may appear only when expenditures like seed production are high or external resources are scarce. In this study, we tested whether reproductive costs are more pronounced under enhanced interspecific competition. In a common garden, we investigated phenotypic correlations between sexual reproduction, clonal growth and storage structures in the grassland perennial, Succisa pratensis. During the past 50 years, habitats of this species have faced an expansion of clonal grasses that increase competition intensity. We simulated this process by growing five populations of Succisa from high- and low-production habitats with its clipped and non-clipped competitor, Agrostis capillaris. In addition, we experimentally removed flower heads of Succisa plants from one population grown with and without A. capillaris. We demonstrated costs of sexual reproduction by flower-head removal (resulting in increased plant size and relative allocation to belowground structures) but not by phenotypic correlations. We found no evidence that reproductive costs increase in a competitive environment and the opposite pattern was shown in both approaches used. However, high competition intensity reduced relative investment to flower-head production. In plants from low-production habitats, competition also reduced the absolute number of flower heads and belowground biomass as a result of smaller plant size. We assume that populations from low-production habitats are more prone to extinction as they have a reduced likelihood of local persistence and of escape to more suitable habitats during advancing succession. Es gibt die Hypothese, dass bei Pflanzen Allokationskonflikte nur auftreten, wenn der Aufwand hoch ist, wie z. B. bei der Samenproduktion, oder wenn die äußeren Ressourcen knapp sind. In dieser Untersuchung testeten wir, ob der reproduktive Aufwand bei stärkerer interspezifischer Konkurrenz stärker betont wird. Wir untersuchten in einem gewöhnlichen Garten die phänotypischen Korrelationen zwischen der geschlechtlichen Reproduktion, dem klonalen Wachstum und den Reservestrukturen bei einer perennierenden Grünlandart, Succisa pratensis. Während der letzten 50 Jahre erfuhren die Habitate dieser Art eine Expansion von klonalen Gräsern, welche die Intensität der Konkurrenz verstärken. Wir simulierten diesen Prozess, indem wir fünf Succisa-Populationen aus Habitaten mit hoher und niedriger Produktion gemeinsam mit ihren beschnitten