According to a study by the University of California at Davis and Stanford University, lichen communities can take decades – and in some cases up to a century – to fully return to chaparral ecosystems after a wildfire.
The study, published today in the journal Diversity and distributions, is the most complete long-term recolonization of lichens after fire to date.
Unlike evergreen forests, California chaparral systems are historically adapted to high intensity fires – they burn hot, quickly, and tend to regenerate quickly. However, with more frequent fires expected in a drier, warmer climate and more inflammation occurring amid a growing human population in these areas, the study indicates that lichen communities may not be given the window. opportunity they need to return to the chaparral shrubs after a forest fire.
“In chaparral systems, lichens can come back 20 to 30 years after a fire, but if you start to burn more frequently several times in a short period of time, there may not be room for these lichens. “, said the co-leader. author Alexandra Weill, who conducted the research as a graduate research student in the Department of Plant Sciences at UC Davis.
OVERVIEWED AND ALL AROUND
Lichens are complex organisms born from a symbiosis of fungi and algae. Overlooked and yet all around, they feature a variety of colorful and intricate shapes and patterns along rocks, branches, and soil in forests and other biomes. They not only provide food for wildlife, they also help retain moisture in their surroundings – an increasingly important service in dry chaparral systems.
“Biodiversity itself also has value,” said co-lead author Jesse Miller, a postdoctoral researcher at UC Davis at the time of the study and currently a lecturer at Stanford. “In our study, plant diversity was low under the dense shrub canopy. But we could find dozens of lichen species in the same area. If we lose these lichens, we lose much of the actual biodiversity that is occurring. is there. “
FIRE NOT FREQUENT “ LICHEN ”
To test lichen recolonization in chaparral systems after a fire, scientists in 2018 sampled lichen communities at two UC Davis nature reserves – Quail Ridge and nearby Stebbins Cold Canyon in Napa and Solano counties. Using records from CAL FIRE and the Quail Ridge Reservation, they identified the boundaries of fires that have occurred on the reserves since 1950. They sampled five fires: the 1953 T. Viue fire, the 1988 station fire, 2005 fun fire, an unnamed 1996 fire and Fire.
After identifying the plots to study in these locations, they crawled under the chaparral to document all the lichen species they could find and its abundance.
They found that fire intolerant species like lichens can be slow to recolonize landscapes after high intensity fires. Most chaparral lichen taxa could be lost if fire intervals shortened to less than 20 years, which has already happened in parts of California, according to the study.
CHAPARRAL OF OLD GROWTH
The researchers also compared the species richness of the lichens found in these previously burnt areas to ancient Chaparral sites with no recorded fire history. They found that such ancient vegetation could promote biodiversity, and the study highlights its value.
“The old-growth chaparral lacks the charisma of a redwood forest,” Miller said. “Most people wouldn’t recognize it as a 100-plus-year-old mini-forest if they walked past it. But all ecosystems have old growth states of unique species that are not found in areas of disturbance. recent. the idea that we need to recognize the value of communities that take time to form. “
The study suggests a land management strategy that targets “a well-maintained mosaic of land types,” including old-fashioned chaparral areas and areas managed with prescribed fires. Such a strategy, combined with home prevention and protection efforts, could help reduce fire risks while maximizing cultural and ecological value.
“For most Californians, chaparral shrubs are the closest and most accessible ecosystems we have,” Weill said. “If you go to Mount Tam, you are hiking chaparral. If you are hiking in Los Angeles, you are in Chaparral. For the average Californian, this is most likely in your garden. But that’s also what makes it a problem because it’s the fires that threaten your home. “
The study was funded by the California Lichen Society.