Barking Up the Right Tree: Intraspecific Variation in Bark Thickness and Wood Density Enhances Abundance via Spatial Occupancy in a Tropical Dry Ecosystem

Tropical dry ecosystems (TDEs) are among the most threatened yet understudied forest types globally. Understanding the factors that shape the distribution and abundance of species in TDEs is necessary to anticipate and mitigate plant biodiversity loss. While interspecific trait differences have traditionally been used to explain species distributions, growing evidence highlights the importance of intraspecific trait variation (ITV) as a crucial component of species’ responses to abiotic and biotic factors. ITV can mediate how individuals respond to environmental heterogeneity, yet its effects on niche properties and abundance of species remain poorly understood, particularly in TDEs. We examined whether ITV in four key functional traits of plants (leaf mass per area, leaf dry matter content, wood density, and bark thickness) predicts niche properties, plot occupancy, and regional abundance of tree species across a 6500 km² TDE in the Eastern Ghats of peninsular India. We found that ITV, especially in structural traits like bark thickness and wood density, was positively associated with niche width and plot occupancy and negatively associated with niche position, leading to higher species abundance. Our results suggest that ITV may enable species to occupy a wider range of conditions and achieve greater abundance in fire-prone and water-limited environments of TDEs.