Older forests recover faster: leaf litter arthropods reveal post-perturbation recolonization dynamics

Arianna Tartara , Karla Neira Salamea, Florian Frenzel, Isabel Benitez-Vegas, Jascha Höpfner, Michael Heethoff

Understanding how ecological communities recover from disturbance is central to predicting ecosystem resilience, particularly in tropical forests where biodiversity and ecosystem functioning are tightly linked. Such landscapes are dominated by secondary forests that have experienced, and continue to experience, disturbances of varying intensity. Leaf litter arthropods play a crucial role in decomposition and nutrient cycling, making it important to understand their recovery dynamics within these heterogeneous, regenerating systems. Here, we investigated the recolonization of leaf litter arthropod communities by combining a forest chronosequence, ranging from active agriculture to old-growth forests, with a controlled perturbation-recovery experiment (PREX) in the lowland Ecuadorian Chocó. Using a litterbag approach, we assessed how mesofauna colonized the new resource over time, and how alpha and beta diversity responded to small-scale disturbances across forest ages, reflecting broader disturbance histories.
Alpha diversity showed weak responses to forest age, with only a marginally significant quadratic trend. In contrast, beta diversity increased significantly along the successional gradient, indicating greater similarity to old-growth communities in older forests. Experimental perturbations reduced both alpha and beta diversity. Effects on alpha diversity were consistent across forest ages and sampling times, but recovery patterns in beta diversity strongly depended on forest age. Older forests exhibited faster convergence toward old-growth community composition, particularly at later stages following disturbance. Indicator species analysis revealed distinct recolonization trajectories upon small-scale disturbance. Communities more similar to old-growth forests showed a gradual shift from early colonizers, such as ants and predatory beetles, to more diverse mesofaunal assemblages, including Collembola and predatory and oribatid mites, reflecting increasing trophic complexity. Conversely, low-similarity plots remained associated with specific oribatid mite assemblages, suggesting the persistence of alternative community states under disturbed conditions.
Our results demonstrate that recovery trajectories are strongly shaped by forest age, with older forests exhibiting higher resilience and faster compositional recovery.