Spatial distribution and performance of native and invasive Ardisia (Myrsinaceae) species in Puerto Rico: the anatomy of an invasion

Abstract

Comparisons between native and invasive congeners are potentially useful approaches for identifying characteristics that promote invasiveness. Those traits for which an invasive exhibits superior ecological performance are likely to contribute to its invasiveness. We tested the hypothesis that invasive tree species have better ecological performance in early life cycle stages than native species in forests where they coexist. We studied locally sympatric populations of the invasive Ardisia elliptica and the native A. obovata (Myrsinaceae) in Puerto Rico. We compared spatial distribution, herbivory and growth in seedlings, seed germination in the field and under controlled conditions, and fruit production. We found the distribution of each species was aggregated in the three categories of size (seedlings, juveniles and adults) and the populations partially overlapped. The invasive species was the most abundant species in every category of size. The two species did not differ in percentage of leaf area consumed and seedlings of both species had the same relative growth rate (RGR) in the forest. However, the invasive species had higher germination success in the field, faster mean germination time in the lab and higher fruit production. It appears that the success of A. elliptica is not through escape from pathogens or herbivores, but by a better performance in fruiting and seed germination in the forest.

Positive frequency dependence undermines the success of restoration using historical disturbance regimes

“…Most simulations started with a clumped distribution to simulate early invasion, which typically begins with invasion fronts that occur in patches ( sensu Levine et al . ; Muñoz & Ackerman ; Liao et al . ).…”

“…If the empty cell was more than 10 cells from an exotic species, the probability of an exotic species being present in the cell was assigned a constant value of 0.00001. Most simulations started with a clumped distribution to simulate early invasion, which typically begins with invasion fronts that occur in patches (sensu Levine et al 2006;Muñoz & Ackerman 2011;Liao et al 2014). After exotic plants were assigned to cells in either a random or clumped manner, all remaining cells were filled with native plants.…”

Comparing germination success and seedling traits between exotic and native pioneers: Cecropia pachystachya versus Macaranga gigantea

“…These differences hold true or are stronger for tropical climates, when compared with confamilials, and when non-native invasive species are compared to native species that are not known to be invasive. Muñoz and Ackerman (2011) found that Ardisia elliptica, exotic to Puerto Rico, germinated more successfully and faster than the native A. obovata. However, the difference in germination success was not statistically significant under controlled laboratory conditions compared to field conditions, and relative growth rates also did not differ significantly between the two species.…”

Potential Germination Success of Exotic and Native Trees Coexisting in Central Spain Riparian Forests

“…The quantity and quality of available propagules influence dispersal and spread in the novel environments [4]. Vegetative reproduction may promote a rapid local dominance, but reproduction by seeds is a crucial step for invasive plants to attain an efficient range expansion and establishment far beyond their introduction point [5][6][7]. According to Hulme and Benkman [8], seeds not only contribute to the colonization of new areas but also allow the replacement of individuals ensuring population persistence after unfavourable periods.…”