Remotely sensing the effects of managed wildfire programs on Sierra Nevada meadows

Abstract

Californian mixed-conifer ecosystems are overstocked and at risk of burning at high stand-replacing severity due to the confluence of a century of aggressive fire suppression and anthropogenic climate warming. Fire needs to be returned to the landscape, and naturally ignited wildfire managed for hazard reduction and ecological benefit is one important tool in accomplishing this. An understudied consequence of allowing naturally ignited fires to burn unabated in the Sierra Nevada is the possible post-fire proliferation of meadow ecosystems, with the managed wildfire program in Yosemite leading to a 160% increase in dense meadow area from 1972-2012. These SN meadows are capable of sequestering more carbon per acre than forests and are host to more biodiversity than any other ecosystem type in the state, making any change that they undergo deserving of close study. Another national park whose natural ecosystems have been the recipient of managed wildfire for over 60 years is Kings Canyon National Park. This thesis project uses remote sensing and object-based image analysis to differentiate between outcomes for frequently-burned versus fire-suppressed meadow ecosystems in a small study area in Kings Canyon National Park. Meadow area in the study region from 1976-2020 has decreased by 36.56% in areas that have received no fire while decreasing by only 4.18% in areas that have burned at least once, lending credence to the hypothesis that managed wildfire is improving the health of Sierra Nevada subalpine and montane meadows.