Vertebrate Biodiversity Loss and Functional Trait Erosion in Tropical Forest Fragments: LiDAR Canopy Structure, Camera-Trap Diversity, and Defaunation Index Across 84 Fragments in Brazilian Atlantic Forest

This study investigates vertebrate biodiversity loss, functional trait erosion, and defaunation index across 84 Atlantic Forest fragments in relation to fragment area, isolation, and LiDAR-measured canopy structural complexity within the context of conservation biology and landscape ecology, an area of growing scientific importance given its implications for Atlantic Forest restoration priority mapping, minimum viable fragment size policy, and functional diversity metrics for conservation assessment frameworks. Using camera-trap richness and occupancy by MaxEnt, airborne LiDAR (point density 8/m2) canopy height model and rugosity index, landscape connectivity by LCP graph (1-km resistance surface), and defaunation index (observed/expected body-mass-weighted abundance), we examine fragment area threshold effect for large-bodied species (>5 kg) requiring home ranges >200 ha absent from fragments <100 ha; canopy rugosity mediating microhabitat diversity supporting specialist species; connectivity enabling recolonization of fragments after local extinction in 84 forest fragments; 4,032 trap-days; 248,400 photo events; 84 vertebrate species detected (28 mammals, 42 birds, 14 reptiles/amphibians); LiDAR coverage of all 84 fragments plus 8 intact forest reference sites drawn from São Paulo state Atlantic Forest remnants (23-24 S, 47-49 W); 84 private and public fragment landowners consented for camera-trap; ALS survey by Embraer Legacy 500 aircraft with Riegl VQ-1560i scanner. Results indicate that fragment area explains 58.4% of species richness variance; canopy rugosity adds 12.4% (partial R2); connectivity adds 8.4%; large mammals (>5 kg) absent from 84% of fragments <100 ha; defaunation index negatively correlated with fragment area (r=-0.84, p<0.001) (p < 0.001), with area explains 58.4% richness variance; large mammals absent 84% of <100ha fragments; r=-0.84 defaunation-area as the primary quantitative benchmark. Concordance between primary and confirmatory measurement approaches exceeded 93%, validating the analytical framework. These findings contribute empirically to conservation biology and landscape ecology and carry actionable implications for the design of programs and policies targeting Atlantic Forest restoration priority mapping, minimum viable fragment size policy, and functional diversity metrics for conservation assessment frameworks.