Assessing intraspecific trait variability during seedling establishment to improve restoration of tropical dry forests

Forest restoration is an effective tool to mitigate climate change, but its implementation in highly diverse and threatened tropical dry forests (TDFs) is particularly challenging due to the hostile environment. Intraspecific trait variability (ITV) in response to these constraints may be very informative for predicting the potential for species acclimation and therefore for improving trait-based species screenings that best match each particular scenario of forest restoration. We analyzed ITV during seedling establishment of three widely distributed and ecologically contrasting TDF species in a greenhouse multifactorial experiment crossing levels of resource availability (nutrients and water) and herbivory to assess the capacity of ITV to discern strategies of seedling establishment and to predict species' growth rates and acclimation potential. The three species studied had contrasting responses to the experimental treatments, suggesting different strategies of seedling establishment. The species with the most plastic pattern of growth performed the best, especially due to its ability to modulate the trade-off of root-to-shoot allocation of biomass depending on nutrient availability. Almost 50% of the variation in the root mass ratio was within species, half of which was a direct response of the treatments, indicating a strong acclimation potential. Individual-level trait measurements, however, were poor predictors of seedling growth rates. ITV, particularly the ability to adapt the pattern of biomass allocation, can be critical during seedling establishment. We propose incorporating information about ITV and the ability of species to modulate their phenotypic expression to cope with environmental variability into programs of forest restoration. Easily implemented and standardized greenhouse experiments are an inexpensive way to obtain high-quality data on the plasticity of forest species, which can be very valuable for predicting the potential of species acclimation and thus improving the selection of species that better match each particular scenario of restoration.