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

Abstract

Tropical dry forests (TDFs) are among the most endangered ecosystems globally, despite their critical socio-ecological importance. In recent decades, tree-planting initiatives have been widely implemented to restore these forests, yielding mixed results. To enhance restoration effectiveness, it is imperative to adopt a predictive approach, focusing on the drivers of seedling performance and their interactions. This study explores how functional traits of planted tree species interact with site environmental conditions to influence seedling survival and growth rates across nine restoration sites of varying ages and climatic conditions within the Peruvian Tumbes-Piura TDFs. While the widely accepted resource-use theory predicts that acquisitive species - focusing on the fast retrieval of resources and characterised by higher specific leaf area and lower wood density - achieve high growth rates in resource-rich environments but experience sharp declines under resource-limited conditions, we found that acquisitive species maintained their high growth rates along the environmental gradient. In contrast, conservative species, expected to be less sensitive to resource variability, exhibited marked declines in growth when water or nutrient availability decreased. Additionally, nitrogen-fixing species did not outperform non-fixers in growth or survival, indicating that nitrogen fixation alone does not confer a consistent advantage in early restoration. Overall, our findings highlight the importance of trait-environment interactions in tree planting performance and underscore the need to align species selection and management strategies with site conditions and broader restoration goals to enhance the success of TDF restoration. Implications for practice- Our findings highlight the importance of considering trait-environment interactions when evaluating growth rates across TDF restoration sites. - Planting acquisitive species, which maintained higher growth rates than conservative species even under resource-poor environmental conditions, can accelerate tropical dry forest recovery in resource-poor restoration sites within the Peruvian Tumbes-Piura region. - While seedling growth is strongly shaped by environmental factors and their interaction with functional traits, survival may depend more on site-specific factors and management interventions, including irrigation and fertilisation. - Selecting species based solely on nitrogen fixation ability may not enhance restoration success, as nitrogen-fixing species did not exhibit higher growth or survival than non-fixers.