Post-Fire Mapping and Report Provide Insights for Southern Sierra

Before and after fine-scale mapping completed in wildfire footprints.

In 2016, the Erskine and Chimney fires burned roughly 18,700 acres east of Bakersfield in the foothills and mountains of the Sierra Nevada. These two fires are situated at the intersection of the Central Valley, Sierra Nevada, and Mojave Desert ecological regions where the overlapping regions and variation in climate, geology, and site history create a floristically unique mash-up of habitats. 

An understanding of how vegetation types respond to disturbance is important for long-term resource management, especially considering interacting threats such as fires and changes in historic fire regimes, invasive plant species, and global climate change.

The California Native Plant Society (CNPS) Vegetation Program has produced fine-scale vegetation maps of woodland habitats for oak (Quercus), pine (Pinus), and juniper (Juniperus) vegetation alliances on BLM-managed lands before and after the Chimney and Erskine fires in the southern Sierra Nevada.

On BLM lands in the Erskine Fire footprint, we documented more than 5,300 acres of woodland habitat in the pre-fire setting, and a reduction in acreage of over 3,300 acres (64%) across all upland woodlands from blue oak (Quercus douglasii) to interior live oak (Q. wislizeni) types post-fire. However, the reduction in acreage from pre- to post-fire was not evenly distributed across all habitat types. For example, the acreage of Jeffrey pine (Pinus jeffreyi), though not widespread in the region, was reduced by 98% while the acreage of California juniper (Juniperus californica), which was much more extensive, was reduced by 72%. This area has a short fire return interval (on a cycle of every 3-4 years on average per CAL FIRE data) with more than 30 fires documented over the last 100 years.

For the Chimney Fire area, we found a decrease in 1,186 acres of mature pinyon pine (P. monophylla) woodlands (98% decrease), and a small increase of 23 acres of regenerating canyon (Quercus chrysolepis) and interior live oak (Q. wislizeni) woodlands in localized spots that were previously pinyon woodlands. The woodland vegetation overall was more significantly impacted by fire, especially because pinyon pine woodlands are not adapted to fire like other cismontane pine and oak woodlands in California.

Plant recovery in these two regions includes fire-adapted shrubs such as Mojave ceanothus (Ceanothus greggii), poodle-dog bush (Eriodictyon parryi), California Flannelbush (Fremontodendron californicum), and Fremont’s bushmallow (Malacothamnus orbiculatus), as well as herbs including various buckwheats (Eriogonum), poppy (Argemone munita), ear drops (Ehrendorferia chrysantha), whispering bells (Emmenanthe penduliflora), woolystars (Eriastrum), etc. Some areas also have been impacted by invasive plants post-fire such as non-native bromes, especially cheatgrass (Bromus tectorum), wild oats (Avena) and filaree (Erodium).

Our vegetation mapping report of the Erskine & Chimney fire areas includes recommendations on next steps, including revisiting 40 long-term monitoring plots on a five-year cycle, continued monitoring of invasive species, and vegetation mapping across all the vegetation types in the Erskine fire area across the next three years.

Thank you to the Bureau of Land Management, Bakersfield Field Office for their support on this project!