Terrestrial lidar versus field surveys to assess microclimate temperature buffering in forests

Forest microclimates are increasingly recognised for their role in mitigating temperature extremes, yet uncertainties remain in which components of forest structure are most important, how interannual climatic variability influences this buffering effect, and whether advanced structure metrics from lidar outperform or complement conventional field surveys. We monitored hourly understory temperatures over six summers in 16 temperate deciduous stands in northern France. Microclimate buffering was quantified as the slope of the linear relationship between microclimate and macroclimate temperatures. We modelled this buffering index using mixed-effects models depending on macroclimate and forest structure, derived either from field or terrestrial lidar surveys. Summers with higher cumulated precipitation and lower temperature exhibited stronger buffering, while forest structure explained most of the variation. Field-based metrics indicated stronger buffering in stands with higher canopy cover, greater diversity of tree diameter classes, and dominance of tree species casting more shade. Lidar-derived metrics showed enhanced buffering in vertically complex forests with greater vegetation volume and biomass preferentially located in the overstory rather than the understory. Field and lidar-based models performed equally well, each explaining about half of the variance in buffering. Combining both approaches yielded only marginal gains in explanatory power. We give practical guidance to forest ecologists and forest managers, to assess and enhance microclimate buffering. Terrestrial lidar is valuable but not necessary compared to classic field inventories, which represent a cost-efficient option. Climate-smart forest management should prioritise continuous cover forestry, structurally diverse stands, and high shade-casting tree species.