Jasper Ridge Prescribed Burn - 1 year later

Back in Mar-2024, Stanford conducted pile burns (aka prescribed burns) in Jasper Ridge Biological Preserve ’Ootchamin ’Ooyakma.  On Feb-18-2025, JRBP’O’O held a research convening on their studies of this work, together with some results from other fuel reduction efforts such as mastication and hand-clearing.

Nona Chiariello, a retired JRBP’O’O researcher and former WPC member, attended the convening and shared some of the changes that were reported resulting from the pile burns:

• Germination of a rare species last seen decades ago
• Germination of invasive species more typical of grasslands
• Wider daily fluctuations in soil temperature and soil moisture, which can affect germination and resprouting plants
• Reductions in plant diversity in the center of burns, versus increases at the perimeter
• Elimination of some fungi and nematodes from surface soil
• Increases in soil pH (greater alkalinity)
• Increases in less degradable forms of carbon

Many studies are in the early stages of lab work or data analysis, such as changes in the chemistry of runoff into streams and Searsville Lake.  Other studies focused on new methods, such as 3-dimensional imaging of plants and vegetation.  

A study of woodrat nests found that in shaded fuel breaks where trees were limbed up and the understory was reduced, woodrat nest occupation levels declined and then recovered after 9 months.  Where poison oak thickets were masticated up to the edge of nests, there was a decline in nest occupation for at least a year, possibly due to a lack of cover for foraging beyond the nest edge. 

Of importance for future maintenance and budgeting, the stewardship team quantified the amount of fuel reduction in each treatment. 

The faculty panel discussed big-picture themes such as three timeframes for thinking about California ecosystems:  historical conditions when tree density was lower; current conditions in which flammable, invasive species are increasingly abundant; and a future in which climate change may favor species from warmer environments.  These have implications for deciding the goals and methods of fuel reduction.

A Stanford student’s Jun-2024 case study of the pile burn covers the collaboration with WFPD, other entities, and Westridge residents, which helped the burn to be a success. Participants remarked on how such a prescribed burn would not have been possible in the past. But times are changing, as “Fuel treatments require the public to understand an uncertain future risk and be willing to frontload the cost of prevention.”

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