Advancing Remote Sensing of Ecosystem Functioning and Health Under Climate Change

Understanding ecosystem functioning is central to assessing how biodiversity responds to accelerating climate change. Remote sensing has greatly advanced this field by tracking vegetation traits linked to primary metabolism, such as photosynthetic activity, nutrient status, and productivity. These metrics are essential for monitoring vegetation dynamics, yet they capture only part of the physiological processes that underpin ecosystem health and resilience. Plant secondary metabolic pathways offer an additional and often overlooked source of information. These compounds mediate defence, stress tolerance, species interactions, and many aspects of ecosystem stability. Because secondary metabolic responses often change rapidly under environmental stress, they can serve as early indicators of physiological decline, well before changes appear in traditional vegetation indices or structural metrics. This makes them valuable for identifying emerging stress conditions in ecosystems already vulnerable or exposed to climate extremes. Despite their ecological importance, secondary metabolic traits remain rarely incorporated into large-scale biodiversity assessments, largely due to the difficulty of detecting them remotely. Their concentrations are relatively low, and the link between leaf chemistry and canopy reflectance becomes increasingly complex with canopy structure and landscape heterogeneity. Recent advances in field spectroscopy, airborne and satellite hyperspectral systems, and high-resolution multispectral time series now offer new opportunities to explore these biochemical dimensions of vegetation function. Combining these observations with ecological understanding can help reveal how secondary metabolic traits vary across environmental gradients, how they respond to climatic extremes such as heatwaves and drought, and how they relate to broader ecosystem processes such as productivity and long-term resilience. Incorporating secondary metabolic information into biodiversity monitoring can greatly expand our ability to detect early stress, quantify ecosystem vulnerability, and understand how vegetation is adjusting to rapid climatic change. As climate pressures intensify, such biochemical indicators may become essential for anticipating ecological responses and supporting more informed conservation and adaptation strategies across ecosystems.