Short-term studies of chaparral ecosystems after fire have shown plant species composition changes and community shifts due to differences in burn severity, elevation, aspect and climate. Previous remote sensing studies have found landscape-scale differences in shrub recovery depend on wind direction, wind speed, and humidity. However, little empirical data exists showing the relationship between interacting abiotic factors and long-term (12 years) recovery after fire based on field measurements. Our goal is to understand what post-fire recovery looks like across a suite of biotic and abiotic variables within chaparral ecosystems tying together both field measurements and remote sensing data. Using landstat images processed with Landtrendr we examined one year and decadal diversity responses on the 2003 Old and Simi fires in southern California. Using Non-metric multi-dimensional scaling and mixed effects models we examined percent cover of understory species within each fire across gradients of burn severity, elevation, and aspect and Hill diversity across and among functional groups (forb, grass, shrub, tree).
Preliminary results suggest that 1) understory plant cover, especially graminoid cover (p-value=0.02), is still highly sculpted by burn severity twelve years later, 2) shrub cover is recovering at a faster rate than understory plants, as burn severity gradients cannot be distinguished from shrub responses (p-value=0.92), but can be differentiated from other functional group responses twelve years post-fire, 3) understory species richness, especially forbs (p-value=0.04) and graminoids (p-value=0.04) are still affected by burn severity, 4) total richness in low and medium severity sites is double that of the high severity sites (p-value =0.05), and 5) climate variables influence the current plant community composition (r2>0.40). We have found that a decade after fire, burn severity is still a significant predictor of plant communities in chaparral ecosystems in all functional groups except shrubs.