More frequent and severe El Niño Southern Oscillations (ENSO) are causing episodic periods of decreased rainfall. Although the effects of these ENSO-induced droughts on tree growth and mortality have been well studied, the impacts on other demographic rates such as reproduction are less well known. We use a four-year seed rain dataset encompassing the most severe ENSO-induced drought in more than 30 years to assess the resilience (i.e., resistance and recovery) of the seed composition and abundance of three forest types in a tropical dry forest. We found that forest types showed distinct differences in the timing, duration, and intensity of drought during the ENSO event, which likely mediated seed composition shifts and resilience. Drought-deciduous species were particularly sensitive to the drought with overall poor resilience of seed production, whereby seed abundance of this functional group failed to recover to predrought levels even two years after the drought. Liana and wind-dispersed species were able to maintain seed production both during and after drought, suggesting that ENSO events promote early successional species or species with a colonization strategy. Combined, these results suggest that ENSO-induced drought mediates the establishment of functional groups and dispersal types suited for early successional conditions with more open canopies and reduced competition among plants. The effects of the ENSO-induced drought on seed composition and abundance were still evident two years after the event suggesting the recovery of seed production requires multiple years that may lead to shifts in forest composition and structure in the long term, with potential consequences for higher trophic levels like frugivores.
Bibliographical noteFunding Information:
National Science Foundation, Grant/Award Number: DEB-1053237 ; Biological and Environmental Research, Grant/Award Number: DE-SC0014363 ; Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Grant/Award Number: P3P3PA_167760; US Department of Energy; Office of Science
MOB was supported by the Swiss National Science Foundation through an Advanced Postdoc Mobility Fellowship (P3P3PA_167760). The plots were set up and monitored with funding from the National Science Foundation CAREER Grant DEB‐ 1053237 and US Department of Energy, Office of Science, Office of Biological and Environmental Research, Terrestrial Ecosystem Science (TES) Program under award number DE‐SC0014363 to JSP. We thank Camila Pizano and two anonymous reviewers for comments that improved the manuscript.
- climate change
- forest succession
- plant–climate interactions
- reproductive phenology
- tropical forests