Scale-Dependent Conditional Relationships Among Ecosystem Functions in Patagonian Headwater Catchments

Mountain catchments integrate environmental gradients, disturbance legacies, and multiscale processes that shape how ecosystem functions vary across space and time. To better understand the role of these spatial processes, we analyzed whether ecosystem-function relationships in Patagonian headwater catchments are organized according to single multifunctionality gradients or are scale-dependent on ecosystem condition and structure. We fitted three expert-constrained Bayesian networks using field-measured ecosystem functions across three spatial resolutions: catchment (n = 12), forest clusters (n = 63), and forest plots (n = 175). Predictive performance varied strongly across scales and functions: at the catchment scale, firewood volume was best predicted (r = 0.79), whereas deadwood carbon stock, tree carbon stock, vascular richness, timber volume, and soil erosion showed negative predictive correlations (r = −0.14, −0.15, −0.33, −0.44, and −0.80, respectively). Specifically, at the forest-cluster scale, firewood volume, live tree carbon stocks, soil erosion, and deadwood carbon stocks were strongly predicted (r = 0.96, 0.81, 0.77, and 0.69). At the plot scale, firewood volume, tree carbon stock, deadwood carbon stock, and understory plant diversity showed the strongest local signal (r = 0.91, 0.67, 0.67, and 0.60). Bayesian networks revealed a recurrent positive wood–carbon structure linking tree carbon stock, firewood volume, deadwood carbon stock, tree carbon sequestration, and some soil responses. In contrast, understory plant diversity was more associated with local drivers such as elevation, canopy cover, slope, and tenure, and erosion control changed direction with scale and forest development stage. Findings show that monitoring should assess carbon- and wood-production-related functions together with biodiversity and soil-related functions across nested spatial scales, because trade-offs and synergies emerge as context- and scale-dependent relationships shaped by shared environmental and management drivers.