Lava to Leaf: Remote Sensing of Post-Eruption Ecological Succession on the 2018 Kīlauea Lava Flows

In the years following the 2018 eruption of Kīlauea, vegetation has begun colonizing the new landscape. This study investigates the environmental factors driving early primary succession on the 2018 Lower East Rift Zone lava flow. A Multi-Vegetation Recovery Index (MVRI), derived from five Sentinel-2 vegetation indices using principal component analysis, was used to monitor vegetation growth from 2018 to 2025. Environmental predictors included distance to existing vegetation, wind exposure, elevation, slope, land surface temperature (LST) change, and lava morphology. A multivariate linear regression was used to evaluate the influence of these factors on MVRI change between 2019 and 2025. Because pāhoehoe and ‘a‘ā lava were unevenly distributed across the flow, propensity-score matching was used to compare morphologies under similar environmental conditions. MVRI exhibited a significant positive temporal trend, indicating substantial vegetation recovery during the study period. Distance to existing vegetation was the strongest predictor of MVRI change (β = −0.249, p = 0.001), followed by elevation (β = 0.232, p = 0.002). Slope, LST change, terrain wind exposure, and lava morphology were not statistically significant predictors. The full multivariate regression model explained 30.5% of the observed variation in MVRI change (R2 = 0.305). After identifying paired samples with comparable environmental conditions, mean MVRI change did not differ significantly between pāhoehoe and ‘a‘ā lava. These results indicate that proximity to surviving vegetation and broader environmental gradients are more strongly associated with early vegetation recovery than lava morphology or modeled wind exposure.