Efficiency and ecosystem-service trade-offs in multifunctional forest management across marginal and non-marginal lands: evidence from eastern Oklahoma.

Multifunctional forest management is widely promoted for climate mitigation and ecosystem-service provision, yet its implications for joint production of services on marginal forest lands remain unclear. This study evaluates technical efficiency and trade-offs among timber production, carbon storage, tree species richness, and water yield across marginal and non-marginal forests in eastern Oklahoma. Plot-level Forest Inventory and Analysis (FIA) data were integrated with gridded climate and watershed-scale hydrological data to construct a panel of 3285 plot-year observations (2007-2025). Output-oriented multi-output stochastic frontier models with a translog specification were estimated, progressively incorporating additional ecosystem services and distinguishing land-productivity classes. Mean technical efficiency was high in timber-carbon models (0.991) but declined when tree species richness and water yield were included (0.952). Marginal and non-marginal lands exhibited comparable efficiency: common-frontier tests showed a difference of only 0.0006 in technical efficiency, slightly favoring non-marginal lands but with negligible practical significance. Thus, marginal lands achieve similarciency despite lower output, highlighting a distinction between productivity and efficiency. Carbon-timber elasticities were consistently close to -1 and robust to functional form and numeraire choice, indicating a structural trade-off partially influenced by distance-function normalization. Including tree species richness and water yield revealed additional negative first-order effects that varied by land productivity. Overall, differences in ecosystem-service provision appear primarily driven by biophysical constraints, with limited evidence of detectable managerial inefficiency given available FIA covariates. These results demonstrate the value of site-specific assessment of ecological production constraints and ecosystem-service trade-offs, while economic suitability and institutional feasibility remain outside the scope of the analysis.