Predicting smoke exposure tradeoffs among forest restoration scenarios in the central Sierra Nevada, California
Abstract
Large wildfires (WF) are becoming more frequent and severe across the western United States, caused in part by climate change and decades of fire exclusion practices. WF emit substantial quantities of air pollutants, which can lead to adverse health outcomes in surrounding communities. Prescribed burns (PB) can mitigate the risk of high-severity fires, yet still emit air pollution. This study aims to evaluate smoke exposures from WF and PB, resulting from six forest management scenarios proposed for a 2.4 million acre landscape in the Central Sierra region of California. Each management scenario varies in the extent and pace of thinning and PB applied annually. In the lowest-level management scenarios (S1-S2), only mechanical fuel treatments are used. PB is introduced in the middle-tier scenarios (S3-S4), applied modestly in combination with mechanical treatments. In the highest-level management scenarios (S5-S6), use of PB is significantly increased across the full landscape in combination with mechanical treatments. For each scenario we first estimate daily fine particulate matter (PM2.5) emissions using the LANDIS-II forest landscape model. Next, using the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT), we estimate PM2.5 concentrations and exposures in downwind communities. We compare the magnitude and spatiotemporal distribution of PM2.5 levels across scenarios. Preliminary results indicate that total emissions (across the 40 year study period and full 2.4 million acre landscape) from the highest-level management scenario (S6 PM2.5Total=4.15x1011g) are greater than those from all other management scenarios; however, when looking only at WF-specific PM2.5, emissions across the study period are greatest in the lowest-level management scenario (S1 PM2.5WF = 1.45x1011g) and decrease as the amount of management increases (S6 PM2.5WF= 8.56x1010g). These estimates may enhance our understanding of how forest restoration practices, intended to mitigate long term wildfire risk, may impact population-level air pollution exposures and how those exposures are distributed over time and space. These insights could contribute to more holistic land management decision-making that promotes both long-term forest resilience and public health.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFMGH31A..06S