Spatial and temporal variation in biomass accumulation in southern California chaparral.

摘要

Wildfires are a common occurrence in chaparral shrublands, and post-fire patterns of biomass accumulation are important for understanding ecosystem productivity and fuel available for future fires. In this research, I examine patterns of biomass accumulation in southern California chaparral shrublands at early and late stages of post-fire recovery using a combination of detailed field work and remote sensing. Using field measurements of a site with adjacent stands of varying ages and high spatial resolution imagery, I examine patterns of species composition and associated levels of biomass to characterize long-term patterns in biomass accumulation. I also evaluate the potential for utilizing shrub growth ring widths to track annual biomass accumulation in the first decade of post-fire recovery, and test for the relationship between biomass and spatial variation in factors related to the energy and water balance. In addition, I examine the potential for extending the use of shrub growth rings to track biomass across larger spatial extents using satellite-based growth metrics. The study of stands of varying ages reveals that biomass shows substantial variation even within stands of the same age, and that species composition is different in younger stands of chaparral compared to the more mature stands. In the study of growth rings, I find that while measuring growth rings widths is a valuable method for tracking biomass accumulation in the first decade following a fire, there is no apparent relationship between biomass and factors related to the energy and water balance. Annual biomass growth, as estimated from shrub growth ring widths, shows a promising relationship with satellite-based metrics of annual growth, indicating the potential for further study of the relationship over larger spatial extents.