Analysis of the impacts of the Soberanes Wildfire on stream ecosystems

Abstract

Wildfires within the western United States are expected to increase in frequency and magnitude but our understanding of how they impact coastal streams is limited. The 2016 Soberanes Wildfire provided an opportunity to determine which biotic and abiotic factors were most impacted by the fire occurring on the California Central Coast. Water quality, benthic macroinvertebrate samples and habitat measurements were taken both before and after the fire. We observed an increase in the levels of phosphorus 4 months and 8 months post-fire which may have contributed to observed increases in microalgae growth. There was a complete loss of shredders in the benthic macroinvertebrate community which could be caused by the loss of vegetation in stream-adjacent riparian areas. These post-fire results were expected based on previous research, however organic material inputs to the stream unexpectedly did not change between pre-and post-fire conditions, which may be due to a delayed increase in inputs from riparian vegetation which short-term monitoring is unable to capture. A long-term monitoring program effort is critical for understanding the recovery of these coastal watersheds from fire.