Meeting with Tony Caprio, the Fire Ecologist, and the Fire Management team at Sequoia and Kings Canyon National Parks was very enlightening. The park developed the concept of prescribed burning in forest in the 1968 and has a brilliant reputation for its prescribed burning program.
Tony started by showing us slices out of giant sequoia tree logs that he had aged using the growth rings, as well as interpreting fire events that leave surprisingly obvious indicators (too bad we can’t do the same with most Australian trees.) He was able to analyse the fire frequency from as early as the 1300’s and worked out that fires burned the sequoias around every 15 years or so. He was able to determine that the fire interval also increases along with the elevation. There was an extended period when fire was kept out of the parks and now it has been successfully reintroduced to maintain the health of the vegetation communities – including of course, the iconic Giant Sequoias.
We met Karen Folger, the Fire GIS Specialist who showed us the method they conceived to prioritise landscape treatments in the Southern Sierra. It is quite ingenious!
They start off by mapping fire hazard by first looking at aspect, elevation and slope, then reclass the park’s vegetation types according to the Scott & Burgan fuel models and classify them in either high, medium or low hazard; then the road accessibility is assessed – most accessible being low hazard and the least being high hazard (most of the area – it is very steep!) then apply weights to the hazard inputs…
Then, yes there’s more…
They look at the wildland urban interface and multiply that, by the hazard for a weighted result;
Next they calculated the ignition risk or the chance of fire occurring based on the occurrence (and do a bit more finessing with density and clumping);
Then they apply the FRID or Fire Return Interval Departure – as formulated by Tony Caprio – where the vegetation is mapped and best fire intervals per veg class (using the sequoia growth rings and fire events and other data) are applied, as well as the historic fire interval being overlaid and time since last fire being deducted and they come up with the Fire Return Interval Departure, or where needs to be burned for ecological reasons.
They overlay these three analyses – hazard, risk and values and out pop the areas that need to be reviewed for treatment.
Apologies to Karen and Tony for my crude retelling of the process, but I understand Karen is soon to write a paper that will explain the process much more eloquently!
Thank you Tony and Karen!
