Trait-environment interactions influence tree planting success in Peruvian tropical dry forests

Tropical dry forests are among the most endangered ecosystems globally, despite their critical socio-ecological importance. In recent decades, various tree-planting initiatives have been undertaken to restore these forests, yielding mixed results. To enhance restoration effectiveness, it is imperative to adopt a predictive approach, focussing on the drivers of seedling performance and their interactions. This study explores how tree species traits and environmental conditions interact to influence survival and growth rates in the Tumbes-Piura tropical dry forests of northwestern Peru. Our findings support the widely accepted growth-mortality hypothesis, indicating that acquisitive species characterised by a high specific leaf area and low wood density achieve faster growth but experience higher mortality compared to conservative species. According to the general resource-use theory, these acquisitive species are also more sensitive to variations in water and nutrient availability, showing steep declines in growth and survival rates as site conditions become less favourable. Interestingly, we found that the growth-mortality hypothesis holds along environmental gradients, with acquisitive species maintaining their high growth rates even under resource-poor conditions, but at the cost of greater vulnerability to mortality. In contrast, the growth rates of conservative species increase markedly when water and nutrients become less limiting. These insights underscore the importance of considering trait-environment interactions in planning tree-planting projects and adapting the management strategy to overall restoration objectives. By doing so, we can improve the outcomes and sustainability of restoration efforts in tropical dry forests.