A 15,000 YEAR VEGETATION AND FIRE HISTORY RECORD, SOUTHERN SANGRE DE CRISTO MOUNTAINS, NEW MEXICO

BAIR, A.N. (1), ANDERSON, R.S. (1,2) AND ALLEN, C.D. (3)

(1) Quaternary Sciences Program, Northern Arizona University, Flagstaff, AZ 86011; (2) Center for Environmental Sciences & Education, Northern Arizona University,Flagstaff, AZ 86011; (3) USGS, Jemez Mountain Field Station, HCR1, Box1, Los Alamos NM 87544

An 807-cm sediment core spanning the past ca. 15,300 cal yr was recovered from Jicarita Bog in the Sangre de Cristo Mountains of New Mexico.  At 3207 m, the site is currently located within the subalpine spruce (Picea) -fir (Abies) forest.  From ca. 15,300 - 12,800 cal yr BP an unusually high fire event frequency is recorded, likely reflecting external factors or an artifact of the sampling method.  The climate was colder than present, with the site situated above treeline and the vegetation distinguished by an alpine tundra pollen assemblage for the first ca. 1000 years.  Warming began by ca. 14,300 cal yr BP, concurrent with an increase in effective moisture.  Treeline moved upslope, placing Jicarita Bog within the subalpine spruce-fir forest.  A brief 400-year cooling event occurred between ca. 12,400 and 12,000 cal yr BP, which may reflect the Younger Dryas event.  Warming resumed at ca. 12,000 cal yr BP, with the pond-to-bog transition at ca. 11,700 cal yr BP.  The fire event frequency during this transition period, from ca. 12,800 - 10,800, cal yr BP, was similar to that of the present.  The early Holocene appears to have been warmer, with warmer and drier conditions beginning at ca. 9,000 cal yr BP and lasting until ca. 4,400 cal yr BP. Peaks in fire event frequency occurred at ca. 7,600 and 5,100 cal yr BP.  The late Holocene is characterized by a cooler and wetter climate, and the low fire event frequency at ca. 2,900 cal yr BP may reflect Neoglacial cooling.  Modern conditions were established at Jicarita Bog by ca. 1,700 cal yr BP.