Invasion of fleshy-fruited plants alter patterns of native seedling recruitment in a temperate forest of Patagonia

Abstract

Biological invasions are one of the main threats to biodiversity and ecosystem functioning. Invasive fleshy-fruited plants can alter seed dispersal interactions, however the implications for the natural regeneration of native fleshy fruited plants are not well understood. In this study conducted in the temperate forest of Patagonia, we evaluated (1) differences in seed rain and seedling recruitment between sites with different degrees of invasion of fleshy-fruited plants; (2) how seed rain determines seedling recruitment at the level of the plant community; and (3) how invasion alters the native seedling recruitment process. For this, we selected 10 study sites; five invaded and five uninvaded by fleshy-fruited plants, establishing one 100 × 30 m2 plot per site. We estimated density and crop size per plant species, seed rain and seedling recruitment. We collected 1857 seeds and recorded 377 seedlings of fleshy-fruited plants across all sites, consisting of 10 native and 6 non-native species. The total number of seedlings was similar between invaded and uninvaded sites, but seed rain and species richness was higher in invaded sites. There was a positive relationship between seed rain and seedling recruitment. Plant invasion had not direct effect on seed rain or seedling recruitment, however, seed rain and seedling recruitment of native species became decoupled in invaded sites. This study shows that the invasive species studied not only spread in the native forest but also reduce the recruitment of native fleshy-fruited plants with which they share seed dispersers. Therefore, controlling exotic species is critical for native forest regeneration.