How are fires and their impacts going to change in the future?

Combined effect of these changes on fires (Team)

We will synthesize our results as a whole team to predict the distribution of fires for the future climate change scenario for the above two pathways under an integrated modeling framework. We will apply the ecological subsection unit based empirical fire models as described in section 3.5 to predict the future distribution of fires. We will estimate the combined effect of the changing frequency and intensity of extreme events such as Santa Ana winds (3.6.1) and the ecosystem response to climate change independent of fire (3.6.2) on fire distributions. We will also quantify the relative contribution from these two pathways. We will also investigate what will be the consequences of projected changes in land use for the dynamics of these fires. We will update the vegetation distribution map by the projected urban expansion from Sanstad et al. (2008) (Fig. 9). This projection was built on the methods and results of Landis and Reilly (2003) and provides urban extents and spatially distributed population output for use in air quality impact scenarios. It predicted the creeping of current urban regions along major highways and into nearby natural lands in southern California. We will estimate both fire frequency and the area burned using our contemporary empirical relationship for this projected land use change. A more realistic prediction should include the interacting processes between fire, vegetation and climate. We will use the MC1 model with calibrated MAPSS and MCFIRE modules. We will apply the empirical post-fire vegetation succession trajectories (section 3.3.2) to modify the transient vegetation response in MC1. We will calibrate and modify the MCFIRE module with the empirical relationships of fire with vegetation and climate (3.5). We will compare the predicted distribution of fires with that simulated from the original MC1 version and examine to what degree and in what areas the modified MC1 will improve the capability of the model to simulate the current distribution of fires in southern California. We will then apply the modified MC1 to predict the distribution of fires under the changing climate scenario. The difference between this model simulation and the simulation with MCFIRE turned off will indicate the importance of fire-vegetation-climate feedback in predicting future fire distribution. Based on the results from section 3.3.3, we will also investigate whether ecosystem responses to changing fire regime reduce or increase the probability of future fires, with two model experiments, one with the 1980’s post-fire trajectory of vegetation recovery and the other with 2000’s trajectory.