Fuel dynamics after a bark beetle outbreak impacts experimental fuel treatments

Fire Ecology

Table 3 Fuel and crown fire potential change by treatment between 2002 (immediately following treatment) and 2016 (following the 2005 to 2012 regional mountain pine beetle outbreak) at the Fire and Fire Surrogate Study. Estimates were derived and tested against zero using linear mixed effects models. ^aFine woody debris (surface wood < 7.62 cm diameter); ^bCoarse woody debris (sound surface wood ≥7.62 cm diameter); ^cLitter and duff (litter and duff layers); ^dCanopy fuels (foliage and materials < 7.62 cm diameter); ^eCanopy base height (lowest height where canopy bulk density exceeds 0.011 kg m⁻³); ^fCanopy bulk density (maximum canopy fuel mass per volume given 4.5 m running mean); ^gProbability of torching (probability of surface fire ascending into crowns given Monte Carlo simulation); ^hCrowning index (6.1 m windspeed required to cause active crown fire)

Response	Treatment	Estimate	Standard error	P-value
FWD^a (Mg ha⁻¹)	Control	5.17	1.30	0.0073
	Burn-only	7.32	1.35	0.0016
	Thin-only	−11.39	3.04	0.0095
	Thin+Burn	−1.02	1.39	0.4904
CWD^b (Mg ha⁻¹)	Control	16.96	7.20	0.0565
	Burn-only	12.02	2.99	0.0070
	Thin-only	−4.34	1.29	0.0152
	Thin+Burn	−0.71	1.29	0.6007
LD^c (Mg ha⁻¹)	Control	−8.59	4.14	0.0832
	Burn-only	13.14	2.28	0.0012
	Thin-only	−0.25	2.66	0.9288
	Thin+Burn	9.82	2.32	0.0055
CF^d (Mg ha⁻¹)	Control	−7.61	3.09	0.0488
	Burn-only	−7.06	2.02	0.0128
	Thin-only	9.47	0.76	<0.0001
	Thin+Burn	3.58	1.11	0.0177
CBH^e (m)	Control	−0.34	0.53	0.5479
	Burn-only	0.53	0.52	0.3498
	Thin-only	−2.54	0.52	0.0028
	Thin+Burn	−0.31	0.55	0.5941
CBD^f (kg m⁻³)	Control	−0.006	0.007	0.4431
	Burn-only	−0.017	0.007	0.0404
	Thin-only	0.015	0.004	0.0080
	Thin+Burn	0.005	0.004	0.2406
PT^g (%)	Control	20.46	7.61	0.0361
	Burn-only	32.97	7.50	0.0046
	Thin-only	4.22	7.50	0.5938
	Thin+Burn	14.02	7.83	0.1237
CI^h (km h⁻¹)	Control	5.84	8.33	0.5096
	Burn-only	11.41	8.19	0.2130
	Thin-only	−25.95	8.19	0.0193
	Thin+Burn	0.77	8.63	0.9318