Stand Age, Standard Retention Density and Site Conditions as Drivers of Shoot Biomass Accumulation in Mediterranean Oak Coppices

ABSTRACT

Mediterranean oak coppices represent an important fuelwood resource in Central Italy, but management decisions are often constrained by limited quantitative evidence on the relative importance of stand development, standard retention, site conditions, and climate in driving shoot biomass accumulation. This study investigated the effects of stand, edaphic, topographic, climatic, and management‐related factors on coppice shoot biomass in Central Italy, with the aim of supporting more evidence‐based and site‐specific management of Mediterranean oak coppices. We analyzed field inventory data from 201 plots across Tuscany, Latium, and Umbria, covering coppices dominated by Turkey oak ( Quercus cerris ), holm oak ( Quercus ilex ), and downy oak ( Quercus pubescens ). Species‐specific linear mixed‐effect models were used to assess the effects of stand age, standard retention density, soil properties, topography, and selected bioclimatic variables on shoot biomass. Model selection indicated that shoot biomass accumulation was primarily driven by stand age in all three species. Stand age had a positive effect on biomass, with fixed effects explaining 28.2% of variability in Q. cerris , 59.7% in Q. ilex , and 25.4% in Q. pubescens . In contrast, standard retention density, soil predictors, topographic variables, and macroclimatic predictors were not retained in the best‐supported species‐specific models. The contribution of the Municipality‐based Forest Management Plan random effect, particularly for Q. cerris and Q. ilex , suggests that local stand‐level factors and management history not captured by the available predictors may strongly influence biomass accumulation. Our results do not support the definition of a universal optimal number of standards for Mediterranean oak coppices based on shoot biomass alone. Rather, they indicate that coppice productivity is mainly age‐driven and that standard retention should be evaluated through site‐ and species‐specific assessments that also consider canopy structure, biodiversity, microclimatic buffering, legal constraints, and ecosystem resilience. Future studies should combine Forest Management Plan data with targeted field measurements of standard biomass, crown cover, microclimate, browsing pressure, and understory biodiversity to better quantify trade‐offs between fuelwood production and ecological functions.