Corroborating Evidence of a Pre-Euro-American Low- to Moderate-Severity Fire Regime in Yellow Pine-Mixed Conifer Forests of the Sierra Nevada, California, USA

Miller, Jay D.; Safford, Hugh D.

doi:10.4996/fireecology.1301058

Fire Ecology

Table 1 Vegetation states for the LANDFIRE biophysical setting Mediterranean California dry-mesic mixed conifer forest and woodland (LANDFIRE zone 6 model number 0610270, online at http://www.landfire.gov/national_veg_models_op2.php).

From: Corroborating Evidence of a Pre-Euro-American Low- to Moderate-Severity Fire Regime in Yellow Pine-Mixed Conifer Forests of the Sierra Nevada, California, USA

Class	Development state	Structure	Cover (%)	Height (m)	Tree diameter (cm)	Transition description
A	Early	All	0 to 100	0 to 10	<12.7	Either tree seedlings develop a nearly continuous canopy and class moves to Class B or C, or chaparral conditions may dominate. Replacement fire mean return interval (MFRI) = 50 yr, mixed fire MFRI = 200 yr. Annually, there is 0.01 probability of succeeding to Class B, and 0.005 probability of succeeding to Class C. After 50 yr, succeeds to Class B.
B	Mid	Closed	51 to 100	10.1 to 25	12.7 to 63.5	Replacement fire MFRI = 75 yr, 80 % of mixed fire (MFRI = 20 yr) moves area to Class C, 20 % of mixed fire stays in Class B. Surface fire MFRI = 36 yr. Insect or disease occurs ∼200 yr, usually with little effect, but 20 % of occurrences move the area to Class C. After 50 yr, succeeds to Class E.
C	Mid	Open	0 to 50	10.1 to 25	12.7 to 63.5	Replacement fire MFRI = 315 yr, 83 % of mixed fire (MFRI = 30 yr) keeps area in Class C, 17 % of mixed fire resets area to Class A. Surface fire MFRI = 15 yr. Insect or disease occurs ∼500 yr, usually with little effect. After ∼35 yr without fire, these stands move to Class B. Patches stay in Class C >100 yr.
D	Late	Open	0 to 50	≥25.1	>63.5	Replacement fire MFRI >1000 yr. Mixed fire (MFRI = 30 yr) usually leaves patch in Class D, but rarely it can move to Class A. Surface fire MFRI = 11 yr maintains Class D. Insect or disease is rather rare (annual probability = 0.001). After 35 yr without fire, this class will transition to Class E.
E	Late	Closed	51 to 100	≥25.1	>63.5	Replacement fire MFRI = 160 yr, 50 % of mixed fires (MFRI = 60 yr) cause no transition, but mixed fire can move area to Class A (MFRI = 70 yr), or Class D (MFRI = 330 yr). Surface fires MFRI = 50 yr. Insect or disease mean return = 250 yr, and usually has little effect on stand structure, but 25 % of the time can move area to Class D.

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