Abstract
BackgroundAlthough plant diversity is postulated to resist invasion, studies have not provided consistent results, most of which were ascribed to the influences of other covariate environmental factors.Methodology/Principal FindingsTo explore the mechanisms by which plant diversity influences community invasibility, an experiment was conducted involving grassland sites varying in their species richness (one, two, four, eight, and sixteen species). Light interception efficiency and soil resources (total N, total P, and water content) were measured. The number of species, biomass, and the number of seedlings of the invading species decreased significantly with species richness. The presence of Patrinia scabiosaefolia Fisch. ex Trev. and Mosla dianthera (Buch.-Ham. ex Roxburgh) Maxim. significantly increased the resistance of the communities to invasion. A structural equation model showed that the richness of planted species had no direct and significant effect on invasion. Light interception efficiency had a negative effect on the invasion whereas soil water content had a positive effect. In monocultures, Antenoron filiforme (Thunb.) Rob. et Vaut. showed the highest light interception efficiency and P. scabiosaefolia recorded the lowest soil water content. With increased planted-species richness, a greater percentage of pots showed light use efficiency higher than that of A. filiforme and a lower soil water content than that in P. scabiosaefolia.Conclusions/SignificanceThe results of this study suggest that plant diversity confers resistance to invasion, which is mainly ascribed to the sampling effect of particular species and the complementarity effect among species on resources use.
Highlights
The pervasive impact of invasive species has motivated a considerable amount of research to question how the characteristics of invaded communities, such as native species diversity, affect the establishment of invasive species [1,2,3,4,5]
Based on the measurement of soil resource availability, we tested whether species diversity significantly increases the invasion resistance of communities, and, if it did, we examined the mechanism by which species diversity affects invasion resistance
The species number, biomass, and the seedlings number of total and exotic invaders were negatively affected by the presence of P. scabiosaefolia and M. dianthera (Table 3), but a significant negative effect of planted-species richness remained
Summary
The pervasive impact of invasive species has motivated a considerable amount of research to question how the characteristics of invaded communities, such as native species diversity, affect the establishment of invasive species [1,2,3,4,5]. Elton [1] hypothesized that invasibility is determined by overall resource availability, which negatively relates to community diversity. Consistent with the hypothesis of Elton [1], most small-scale grassland experiments have shown that a more diverse plant community has a higher resistance to invasion by non-native plants [5,6,7,8,9]. Resource availability and fluctuation are important factors in determining the invasion resistance of plant communities [16,17]. Communities with higher plant diversity have a higher probability of including a highly competitive species (which most likely has a strong demand for resources) and have a greater ability to resist invasion [20]. Plant diversity is postulated to resist invasion, studies have not provided consistent results, most of which were ascribed to the influences of other covariate environmental factors
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