Demographic costs and benefits of natural regeneration for tropical trees

Whether to plant trees or enable forest to return naturally is a fundamental question for tropical forest restoration. An overlooked aspect of this debate is that both restoration strategies rely on natural recruitment to regenerate biodiversity, as native tree seedlings recruit in the understory of restoration sites. While we know a lot about the rates of recruitment during tropical forest restoration, the long-term fate of these seedlings has remained a mystery. This is problematic, because the long-term success of any restoration project relies on tree seedling completing their life cycle to become seed sources.  In a new paper, we track the fate of natural recruits over a 7 year period in experimental reforestation plots in Los Tuxtlas, Mexico. We quantified growth, survival, and reproduction rates and then used a computer model to combine all these vital rates and ask, what is the probability that a newly-arrived seedling can grow and survive to reach reproductive maturity? We found an overall benefit to natural regeneration: tree seedlings have a much higher chance of achieving reproductive status in these plots. Our work is one of the first full life-cycle analyses of trees during restoration and adds a new perspective on the ongoing debate between active restoration and natural regeneration.