Scale-dependent controls on forest gaps shaped by large trees and topographic heterogeneity

The size, number, and distribution of forest canopy gaps vary significantly across spatial scales, yet their relationships with underlying drivers, such as large trees, topography, and soil properties, remain insufficiently comprehended. We utilized an unmanned aerial vehicle to measure forest gap patterns (size, number, and aggregation) at seven spatial scales (20–400 m) in four subtropical forests and quantified the effect of large trees, topography, and soil in shaping gap patterns using ground inventory data. Gap size and aggregation showed significant variation across scales. Large trees and topographic complexity were major factors of gap patterns, with their effects depending on scale. Large trees in two forests had a significantly negative effect on gap size and density at the 20-m scale, but this effect was weaker and positive at the 100-m scale. Topography had the strongest effect on gap aggregation at a small scale (20 m) and on gap size and density at a larger scale (100 m). These results underscore the importance of spatial scale in understanding forest dynamics and highlight how community-level factors shape canopy structure. Identifying scale-dependent drivers of gap patterns can inform gap-based restoration and conservation strategies. Forest managers can reduce gap clustering by protecting large trees, especially in wind-prone areas, helping to maintain canopy structure, promote species diversity, and enhance ecosystem resilience.