UAV in long-term ecological monitoring: contributing to baselines for ecosystem assessment and management

Long-term ecological monitoring enable to build baselines for ecosystem dynamics and assess pressures from recurrent droughts, warming, and disturbance regimes. Over the past decade, Unmanned Aerial Systems (UAS) have transitioned from opportunistic observation tools into essential proximal remote sensing platforms, bridging the critical spatial and temporal gap between in situ field measurements and satellite Earth observation. This presentation reviews methodological advances and operational lessons learned from more than a decade of drone-based ecological monitoring in protected areas.

Leveraging ultra-high-resolution multispectral. LiDaR and thermal sensors, we demonstrate feasible workflows for the monitoring of terrestrial and aquatic vegetation status, including phenology, disturbance effects and trends. Replicated and ad-hoc flight missions allow monitoring restoration actions, recovery after disturbance or identifying invasive species and algal blooms to inform practitioners and decision-making.

By coupling UAV imagery with in situ data we are able to monitor mast seeding (i.e. acorn production), crown defoliation, and early-stage dieback symptoms less detectable by standard satellite pixels. Furthermore, multi-rotor and fixed-wing UAS payloads facilitate proximal mapping of topsoil moisture dynamics and canopy water stress at sub-decimetre scales, providing crucial insights into plant-soil-water interactions in semi-arid rangelands and post-fire regenerating shrublands.

Additionally, UAS datasets serve as robust, spatially explicit ground-truth benchmarks for calibration, validation and upscaling to medium- and high-resolution satellite constellations. Harmonizing drone flight protocols, radiometric calibration routines, and data repositories is imperative to translate drone imagery into standardized Essential Ecosystem Variables and actionable management indicators. Drones are not only suitable for mapping, we can also use them to collect samples in a systematic way, or to autonomously fly below tree canopies.

In summary, this keynote addresses the most frequent drone applications for long-term ecological monitoring of natural areas that can be used to measure and upscale in situ measurements to satellite images and highlights applications providing baseline for the management of forest health, drought resilience, and sustainable protected areas stewardship under global change.