Drivers of Saproxylic and Forest Coleoptera Diversity across Vegetation Types and Microclimatic Gradients in Tazekka National Park, Morocco

Mediterranean mountain forests represent critical reservoirs of insect biodiversity currently threatened by climate change and habitat degradation. Saproxylic and forest Coleoptera play a fundamental role in nutrient cycling, deadwood decomposition, and overall ecosystem stability, making them excellent bioindicators of forest health. However, their distribution patterns across Mediterranean microclimatic gradients remain understudied. This study evaluates the influence of relative humidity, temperature, and forest stand types on Coleoptera community structure in Tazekka National Park, Morocco.

Field sampling was conducted during 2024 and 2025 across four major forest formations: Zean Oak (Quercus canariensis), Holm Oak (Quercus ilex), Cork Oak (Quercus suber), and Atlas Cedar (Cedrus atlantica). A standardized sampling design using 18 traps per year was deployed monthly. Environmental factors (altitude, temperature, relative humidity) were measured in situ. Community metrics, diversity indices (Shannon, Simpson, Pielou), and non-parametric Spearman rank correlations were computed using R software.

A total of 3,499 individuals across 44 families were identified. Holm Oak exhibited the highest total abundance (1,410 individuals), whereas Zean Oak recorded the highest overall family richness (44 families) and diversity (H' = 2.57, D = 0.88). High fidelity was observed among key saproxylic and wood-associated guilds, notably Bostrichidae (71.4%) and Brentidae (72.7%) in Zean Oak, Cerambycidae (64.6%) and Anobiidae (72.5%) in Holm Oak, and Nitidulidae (64.2%) in Cedar. Relative humidity was positively correlated with total abundance (Rho = 0.519, p = 0.0836), while temperature showed no linear effect (Rho = -0.166, p = 0.606).

Stand composition, structural complexity, and microclimatic moisture are major drivers structuring saproxylic and forest beetle communities. Preserving mature forest stands with abundant deadwood and canopy cover is vital to maintaining ecological functions and mitigating climate impacts in Mediterranean ecosystems.