The Impact of Herbivory and Competition on Flowering and Survival during Saltmarsh Succession

Abstract

For succession, the establishment and turnover of plants, in terms of generative spreading and renewal, is of crucial importance. Especially the success of seedling establishment into the existing vegetation might be of prime importance for the further development of plant species composition. Flowering, on the other hand, is the necessary first step towards generative output and later seed set. In a chronosequential gradient of a saltmarsh succession, we investigated the performance of transplants of three common species under different conditions: Artemisia maritima, Atriplex portulacoides and Plantago maritima were transplanted as seedlings and mature plants into plots in early‐, mid‐, and late‐successional stages (15, 30 and 40 years) on the Dutch island of Schiermonnikoog. Natural herbivory (by hares and geese) and neighbourhood competition were excluded in a factorial design. Flowering and survival rates of the three species were generally greatly reduced under natural conditions, compared to competition‐ and herbivory‐free plots. The survival rates of Artemisia maritima and Plantago maritima reflect their position as early‐successional species: early in succession, both show their highest survival and abundance. For late‐dominant Atriplex portulacoides a different explanation has to be invoked for the medium‐high survival and low abundance: probably winter grazing by hares and the importance of a high nitrogen supply rate, rather than flowering and survival, determine its low abundance in the early and mid‐phase of this saltmarsh succession. Some long‐term impacts of herbivores affecting flowering and survival are discussed.

Diagnóstico ambiental das marismas no estuário da Lagoa dos Patos - RS

“…Estes impactos sobre a cobertura vegetal podem afetar os processos biológicos e ecológicos nas marismas, tais como a produção de biomassa (Hackney & De La Cruz 1981, Bazely & Jefferies 1985, reprodução das plantas (Turner 1987, Dormann & Bakker 2000, diversidade de espécies (Brewer et al 1998, Bos et al 2002, Bakker et al 2003, Feldman & Lewis 2005, Madanes et al 2007, disponibilidade de nutrientes (Bazely & Jefferies 1985), composição e abundância de fauna (Isacch et al 2004). Costa & Marangoni (2000) definem como impactos estruturais os efeitos adversos das perturbações antrópicas e natural (erosão) que afetam a integridade da cobertura vegetal das marismas.…”

Cattle effects on the resource allocation in woody species of Andean Patagonian shrublands and forests.

“…En un trabajo previo, se encontró que R. magellanicum disminuyó 25 veces la producción de flores y 10 veces la de frutos en presencia de ganado (de Paz & Raffaele 2013). Estos resultados coinciden con los encontrados en otros estudios donde se observó que la producción de frutos y semillas puede disminuir debido a la herbivoría (Ollerton & Lack 1998;Dormann & Bakker 2000;Sasal 2009).…”

A Field Experiment to Assess the Transplant Success of Salt Marsh Plants into Tidal Wetlands

“…Many individual plants can be separated from one parent clump suggesting that relatively small areas could be used for the on-growing transplants. However, these field nursery sites may need to be protected from herbivory by fencing and repellent (Dormann and Bakker 2000).…”