Using a multiscale lidar approach to determine variation in canopy structure from African forest elephant trails

Abstract

ABSTRACTRecently classified as a unique species by the IUCN, African forest elephants (Loxodonta cyclotis) are critically endangered due to severe poaching. With limited knowledge about their ecological role due to the dense tropical forests they inhabit in central Africa, it is unclear how the Afrotropics would change if forest elephants were to go extinct. Although their role as seed dispersers is well known, they may also drive large-scale processes that determine forest structure, through the creation of elephant trails and browsing the understory and allowing larger, carbon-dense trees to succeed. Multiple scales of lidar were collected by NASA in Lopé National Park, Gabon from 2015-2022. Utilizing two airborne lidar datasets and one spaceborne lidar in an African forest elephant stronghold, detailed canopy structural information was used in conjunction with elephant trail data to determine how forest structure varies on and off trails. Forest above elephant trails displayed different structural characteristics than forested areas off trails, with lower canopy height, canopy cover, and different vertical distribution of plant mass. Less plant area density was found on trails at 1 m in height, while more vegetation was found at 12 m, compared to off trail locations. Trails with previous logging history had lower plant area in the top of the canopy.