Defaunated and invaded insular tropical rainforests will not recover alone: recruitment limitation factors disentangled by hierarchical models of spontaneous and assisted regeneration
Data files
Oct 25, 2023 version files 108.15 KB
Abstract
- Most tropical forests are now severely degraded and their ability to recover is highly dependent on frugivores which ensure seed dispersal for most woody plants. The global collapse of large vertebrates therefore raises major concerns about tropical forest succession, but few field studies have been conducted to disentangle recruitment limitations during disrupted succession.
- This study took place on Réunion (Mascarenes) where all large native frugivores have been extinct since human colonisation in 1665 and where multiple invasions threaten native ecosystems. We set up 20 experimental blocks on a lava flow dated back to 1800, in plant-impoverished post-defaunation vegetation bordered by old-growth forests. We assessed fecundity, seed dispersal and seedling recruitment of the complete fleshy-fruited plant community and used Bayesian analyses to disentangle the impact of multiple factors on these key processes. In the same blocks, we sowed four native trees assumed to be disperserless to test their capacity to establish, controlling for two additional post-dispersal limitations (seed predation and competition with invasive plants).
- On the flow, small-seeded native plants were fairly dispersed but did not recruit, probably due to strong competition with invasive plants; the few native species that recruited somehow were mostly medium-seeded plants that were still dispersed; large-seeded plants were absent from seed rain (which shows that invasive frugivores did not replace extinct ones) and subsequently from spontaneous recruitment. Instead, some alien plants, notably the tiny-seeded highly-dispersed Clidemia hirta and the medium-seeded Psidium cattleianum largely dominated seedling recruitment. Native plants recruited better at the forest margin, including some large-seeded species nearby mother trees.
- Sown large-seeded species were able to emerge and survive in all plots whatever the treatment, which demonstrates that dispersal loss was the primary cause of regeneration failure on the flow.
- Synthesis. The strong modulation of the establishment capacity of native plants by seed mass shows that invasive plants win by forfeit of large-seeded plants after native frugivores loss. Our study emphasises the fundamental role of dispersal loss and competition with invasive plants in the disruption of ecological succession, as well as the urgency of restoring seed dispersal and strengthening biosecurity regulations.
README: Defaunated and invaded insular tropical rainforests will not recover alone: recruitment limitation factors disentangled by hierarchical models of spontaneous and assisted regeneration
https://doi.org/10.5061/dryad.sj3tx96b5
Description of the data and file structure
The data are structured in a spreadsheet containing 6 sheets:
'obs_study_process' presents process measurements (fruit production, seed dispersal, seedling recruitment) for the 50 plant species studied in the observational study;
'obs_study_plot' presents the data for the 40 plots in the observational study;
'exp_sowing_count' presents count data over time for the 4 species of the experimental sowing;
'exp_sowing_height' presents height measurements over time for the 4 species of the experimental sowing;
'species' presents the characteristics (taxonomy, traits, status) of the plant species from the observational and experimental studies;
'metadata' describes all the variables in the five preceding sheets.