What are long term impacts of fires on vegetation recovery processes and trajectories?

Effects of fire frequency on vegetation recovery (UCI and JPL)

Recent increases in fire frequency in Southern California may be causing a widespread conversion of shrubland to grassland (Syphard et al. 2006; Talluto and Suding 2008). Conversion from shrubland to grassland has the potential to further raise fire vulnerability by increasing the production of fine fuels, thereby causing a positive fire frequency feedback. We will examine the effect of fire frequency on species composition during recovery using the approaches described in Section 3.3.1. The short term recovery from the Santiago and Esperanza fires will be analyzed with field measurements along gradients in the number of previous fires. We have identified nearby, topographically well-matched plots that were burned in the 2007 Santiago Fire and that had previously burned 0, 1, 2, or 3 times since 1965. We will focus on the post-fire changes in abundance of species, and will compare life form (shrubs vs. herbaceous), as well as natives vs exotics. Similarly, we will explore the immediate recovery using time series of MASTER and MODIS imagery. The MODIS time series should prove especially useful for separating annual grasses from evergreen shrubs, based on phenology. We will put all the available field and satellite observation data together and synthesize the impact of fire severity and fire frequency on a broader spatial and temporal scale. Both the rate of recovery and type conversion will be examined and empirical trajectories will be built for various plant function types. We will examine the complex patterns of postfire recovery and succession between coastal and interior associations of various vegetation types.