Newswise – Irvine, California, February 28, 2024 – In a study recently published in the journal ecologyScientists at the University of California, Irvine are uncovering the complicated dance between drought, wildfires and invasive species in southern California’s coastal sage scrub ecosystems.

Entitled “Long-term drought promotes invasive species by reducing wildfire severity,” the study led by Sarah Kimball, Ph.D., director of the Center for Environmental Biology at UCI, illuminates the critical interplay of these factors and their profound impact on the environment Ecosystem health.

Research conducted in the Loma Ridge Global Change Experiment shows how prolonged drought acts as a catalyst, not only affecting the severity of wildfires but also paving the way for invasive species to take center stage. By simulating drought conditions, the study illustrates connections between climate change, forest fire dynamics and changes in plant communities.

Reduced fire severity associated with drought creates an environment conducive to invasive species. Non-native grasses in particular thrive under these conditions, potentially leading to changes in the landscape and the abundance and diversity of native species.

The results have significant implications for the management of these vulnerable ecosystems. The study advocates for strategies that carefully consider wildfire frequency and post-fire control of invasive species. Controlled burns, commonly used in other ecosystems, are not recommended for coastal sage scrub systems because they may inadvertently promote invasive species.

Kimball, the paper’s corresponding author, emphasizes the importance of experimental work in elucidating the dynamics between drought, wildfires and invasive species. “This study is unique in that repeated experimental plots were exposed to different rainfall regimes for several years prior to the forest fire. “This provides an opportunity to test how a range of pre-fire weather conditions affected fire severity and resulting plant community composition,” she said.

Kimball adds, “We found feedbacks between invasive species and low-severity wildfires, suggesting that control fires should not be conducted in this system.”

Research has implications for the public beyond academic circles. As wildfires increasingly impact communities, understanding the factors that influence their severity is paramount. The study re-evaluates traditional wildfire management approaches and highlights the urgent need to address climate change to preserve natural ecosystems.

Nature conservation; the U.S. Department of Energy, Office of Science, Biological and Environmental Research, grant/award number DE-SC0020382; and the Natural Communities Coalition supported the research.

About the University of California, Irvine: Founded in 1965, UCI is a member of the prestigious Association of American Universities and is ranked among the top ten public universities in the country US News and World Report. The campus has produced five Nobel Prize winners and is known for its academic achievements, world-class research, innovation and its anteater mascot. Under the leadership of Chancellor Howard Gillman, UCI has more than 36,000 students and offers 224 degree programs. Located in one of the safest and most economically vibrant communities in the world, the company is Orange County’s largest employer, contributing $7 billion annually to the local economy and $8 billion statewide. For more information about UCI, see

Media access: Radio programs/stations may use an on-campus ISDN line to interview UCI faculty and experts for a fee, subject to availability and university approval. For more UCI news, see For more resources for journalists, see


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