Invasion ofAgavespecies (Agavaceae) in south‐east Spain: invader demographic parameters and impacts on native species

Abstract

Several mechanisms have been proposed to explain the success of invasive species in new environments. A species may become invasive when a new site provides the potential for positive rates of population growth. This may be the case of several Agave species introduced to Spain in the 1940s. In this paper we document factors that promote large increases of populations of these species, and their effects on native plant communities in two sites of SE Spain. Results showed higher rhizome and bulbil production, and higher establishment rates by agaves in sandy soils than in clay soils. In their native habitats, agaves have low establishment rates and sandy soils are rare. This suggests that sandy soils are an opportunity which releases the clonal reproduction of Agave. The effects of agaves on the physiological performance and reproduction of native species were negative, positive or neutral, depending on the size and rooting depth of neighbours. Assemblages of native species growing within Agave stands had lower diversity than non‐invaded sites. Our data show that Agave stands have positive growth rates in SE Spain, and suggest that sandy soils are a niche dimension enhancing the invasion in these new habitats.

Factores ambientales relacionados con la cobertura de Agave angustifolia (Asparagaceae) en el matorral costero de Yucatán, México

“…La alta frecuencia relativa de individuos de tamaño II y III puede ser consecuencia de que cada individuo es capaz de producir varios clones en estas categorías, sobre todos los originados por rizomas. Se ha reportado que estos clones tienen una alta tasa de sobrevivencia gracias al aporte de agua y fotosintatos de la planta madre (Badano y Pugnaire, 2004). En este estudio se observó que individuos menores a 50 cm de altura ya son capaces de producir clones rizomatosos.…”

Population structure and growth of a non-native invasive clonal plant on coastal dunes in Southern Brazil

“…Species that can grow vigorously, reaching higher cover/biomass (large and succulent leaves), and are taller than members of invaded resident communities, including dominant species, tend to cause the strongest impacts on these communities (Brabec and Pyšek, 2000;Hedja et al, 2009).…”

“…Furcraea foetida is invasive in several countries, such as South Africa and overseas departments of France (e.g. Reunión Island) (Baret et al, 2006;Crouch and Smith, 2011). Its invasiveness is highly associated with reproduction by thousands of bulbils per plant (Crouch and Smith, 2011).…”

“…Propagules may also arrive on coastal dunes from the ocean especially with high tides (Aptekar and Rejmánek, 2000). Non-native invasive species impacts on costal dune ecosystems include native species displacement, decreasing soil stabilization functions (Kim, 2005), competition for resources (Santoro et al, 2012), and native species richness or diversity decline (Badano and Pugnaire, 2004;Carboni et al, 2010).…”

Differential allelopathy between genders of an invasive dioecious tree on desert plants

“…After their establishment, these invasive plants can prevent the recovery of native vegetation in several ways (Levine et al, 2002;Didham et al, 2005). Higher competitive ability is a major mechanism by which invasive plants can interfere with the recovery of native communities (Eliason and Allen, 1997;Bakker and Wilson, 2001;Badano and Pugnaire, 2004;Castro et al, 2010). Nevertheless, some invasive species also produce secondary metabolites that can inhibit the germination and growth of other plants in their surroundings (Ridenour and Callaway, 2001;Inderjit et al, 2008;Zhang and Fu, 2009).…”