Variability in <i>Pterocarpus erinaceus</i> Poir. Traits Along an Aridity Gradient Provides Insights Into Its Adaptation to Dry Environmental Conditions

ABSTRACT Understanding species adaptation to environmental changes is crucial to guide conservation and habitat restoration. This study examined variability in Pterocarpus erinaceus Poir. traits along an environmental gradient in Benin, ranging from humid (Guinean), subhumid (Sudano‐Guinean) to semi‐arid (Sudanian) zones. Data on fourteen morphological and functional traits were collected from 120 trees along this gradient. Canonical discriminant analysis was used to identify traits that differentiate each climate zone, while redundancy analysis was employed to explore relationships between discriminative traits and environmental variables. Both univariate and multivariate (MVPi) plasticity indices were further computed to assess trait variability. Petiolule length (PeL), petiole length (PEL), diameter at breast height (DBH), number of branches (NB), and leaf mass per area (LMA) were the most discriminative traits. PeL, PEL, and LMA significantly decreased from arid (0.7 ± 0.15 cm, 4.5 ± 0.67 cm, 69.44 ± 15.17 g/m 2 , respectively) to humid zones (0.4 ± 0.08 cm, 3.8 ± 0.48 cm, 40.9 ± 10.90 g/m 2 , respectively), whereas NB declined from humid (11.7 ± 4.68) to arid zones (6.68 ± 1.64). Temperature, rainfall, and aridity positively influenced PEL and PeL but negatively influenced NB. DBH, NB, and LMA were negatively related to soil type. Substantial plasticity (0.45–0.50) was observed at individual trait level. When aggregated over all traits (MVPi), trait plasticity was slightly higher for SGZ vs. SZ and SZ vs. GZ compared to that for SGZ vs. GZ. Our findings highlight the function trade‐offs underlying the growth and local adaptation of the species across the climatic zones. These insights underscore the importance of conserving the species' subpopulation within their respective ecological zones. Future research should explore the species' genetic diversity and adaptation mechanisms to enhance its conservation strategies.