Utility of an Instantaneous Moisture Meter for Duff Moisture Prediction in Long-Unburned Longleaf Pine Forests

14 Duff fires have been implicated in overstory mortality and soil heating in long-unburned pine 15 forests. In the South’s punctuated climate, duff moisture can change rapidly, falling below 16 moisture thresholds that protect trees or increasing following brief downpours. To date, 17 managers lack an instantaneous measure of duff moisture, a hurdle to the implementation of 18 prescribed burns. Here we evaluate a low-cost tool, the Campbell Scientific Duff Moisture Meter 19 (DMM) 600, to estimate duff moisture content in the field. Comparisons of the DMM 600 20 outputs with paired oven-dried duff fuel samples revealed statistically significant differences, 21 with DMM 600 moisture output explaining 54 percent of the variation in oven-dried moisture 22 content. Comparisons with previously published data demonstrate that large variations in duff 23 moisture calculations may predict a broad range of observed duff consumption and overstory tree 24 mortality levels, limiting its applicability for some management objectives. DMM 600 outputs 25 were only weakly correlated with Keetch-Byram Drought Index (R = 0.30). In addition, we 26