Tropical forests can vary enormously in their 3D structure and dynamics even within the same landscape. However, the drivers that underpin this local-scale variation in forest dynamics remain poorly understood. Here we used repeat airborne laser scanning data acquired across >1500 ha of old-growth tropical forest in Malaysian Borneo to explore how soils and topography influence rates of gap formation, closure and canopy growth across the landscape. We found that both canopy gains and losses were 2.5–4.7 times greater in low-lying alluvial forests on fertile soils compared to nearby nutrient-depleted heath forests on hilltops. Moreover, we found that variation in canopy 3D structure and dynamics were tightly coupled across the landscape, with taller and more structurally heterogeneous canopies also experiencing faster rates of gap dynamics. Our study highlights the key role that soils and topography play in shaping the structural complexity and dynamics of tropical forest landscapes.

In tropical forests, trees strategically balance growth patterns to optimize fitness amid multiple environmental stressors. Wind poses the primary risk to a tree’s mechanical stability, prompting developments such as thicker trunks to withstand the bending forces. Therefore, a trade-off in resource allocation exists between diameter growth and vertical growth to compete for light. We explore this trade-off by measuring the relative wind mortality risk for 96 trees in a tropical forest in Panama and testing how it varies with tree size, species and wind exposure. Surprisingly, local wind exposure and tree size had minimal impact on wind mortality risk; instead, species wood density emerged as the crucial factor. Low wood density species exhibited a significantly greater wind mortality risk, suggesting a prioritization of competition for light over biomechanical stability. Our study highlights the pivotal role of wind safety in shaping the life-history strategy of trees and structuring diverse tropical forests.