Unveil the unseen: Using LiDAR to capture time‐lag dynamics in the herbaceous layer of European temperate forests

1. To understand time-­lag dynamics in the response of biodiversity to contem- porary environmental changes (e.g. macroclimate warming and atmospheric pollution), we need to consider former anthropogenic forcing factors such as past land uses and management practices that can have both compounding and confounding effects. This is especially true in European temperate forests, where legacies from past human activities have left strong imprints on today’s understorey plant species composition, generating long-­term lagging effects which can be mistakenly attributed to more recent macro-­environmental changes. 2. By combining the expertise of plant, soil and historical ecologists together with remote sensing scientists, we review the potential of light detection and ranging (LiDAR) to unveil ghosts from the past in terms of former land uses and manage- ment practices. 3. We show that imprints from past land uses and management practices can still be captured today through well-­chosen LiDAR-­derived variables describing, at sub-­decimetre scale, the vertical and horizontal micro-­variations of vegetation and terrain structure hidden below treetops. 4. Synthesis. We encourage plant and soil ecologists to use LiDAR data and to work with historians, archaeologists and remote sensing scientists in order to select meaningful LiDAR-­derived variables to account for time-­lagged biotic responses to long-­term macro-­environmental changes.