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<p>We present an exploratory study examining the use of airborne remote-sensing observations to detect ecological responses to elevated <span class="inline-formula">CO₂</span> emissions from active volcanic systems. To evaluate these ecosystem responses, existing spectroscopic, thermal, and lidar data acquired over forest ecosystems on Mammoth Mountain volcano, California, were exploited, along with in situ measurements of persistent volcanic soil <span class="inline-formula">CO₂</span> fluxes. The elevated <span class="inline-formula">CO₂</span> response was used to statistically model ecosystem structure, composition, and function, evaluated via data products including biomass, plant foliar traits and vegetation indices, and evapotranspiration (ET). Using regression ensemble models, we found that soil <span class="inline-formula">CO₂</span> flux was a significant predictor for ecological variables, including canopy greenness (normalized vegetation difference index, NDVI), canopy nitrogen, ET, and biomass. With increasing <span class="inline-formula">CO₂</span>, we found a decrease in ET and an increase in canopy nitrogen, both consistent with theory, suggesting more water- and nutrient-use-efficient canopies. However, we also observed a decrease in NDVI with increasing <span class="inline-formula">CO₂</span> (a mean NDVI of 0.27 at 200&thinsp;g&thinsp;m<span class="inline-formula">⁻²</span>&thinsp;d<span class="inline-formula">⁻¹</span> <span class="inline-formula">CO₂</span> reduced to a mean NDVI of 0.10 at 800&thinsp;g&thinsp;m<span class="inline-formula">⁻²</span>&thinsp;d<span class="inline-formula">⁻¹</span> <span class="inline-formula">CO₂</span>). This is inconsistent with theory though consistent with increased efficiency of fewer leaves. We found a decrease in above-ground biomass with increasing <span class="inline-formula">CO₂</span>, also inconsistent with theory, but we did also find a decrease in biomass variance, pointing to a long-term homogenization of structure with elevated <span class="inline-formula">CO₂</span>. Additionally, the relationships between ecological variables changed with elevated <span class="inline-formula">CO₂</span>, suggesting a shift in coupling/decoupling among ecosystem structure, composition, and function synergies. For example, ET and biomass were significantly correlated for areas without elevated <span class="inline-formula">CO₂</span> flux but decoupled with elevated <span class="inline-formula">CO₂</span> flux. This study demonstrates that (a) volcanic systems show great potential as a means to study the properties of ecosystems and their responses to elevated <span class="inline-formula">CO₂</span> emissions and (b) these ecosystem responses are measurable using a suite of airborne remotely sensed data.</p>