Vallecito Country Market - USVCM001
Bigio, E.R., Swetnam, T.W., Baisan, C.H.

Dating method: crossdated

Sample storage location: LTRR, University of Arizona

Reference:
Bigio, E., Swetnam, T.W., Baisan, C.H.  2010. A comparison and integration of tree-ring and alluvial records of fire history at the Missionary Ridge Fire, Durango, Colorado, USA. The Holocene. 20:7:1047 - 1061. DOI 10.1177/0959683610369502. 

Abstract: 
We used tree-ring and alluvial sediment methods to reconstruct past fire regimes for a mixed conifer forest within a 1 km2 drainage basin which was severely burned by a wildfire near Durango, Colorado. Post-fire debris flow events incised the valley-filling alluvial sediments in the lower basin, and created exposures of fire-related of deposits of late-Holocene age. Tree-ring and alluvial sediment fire history records were created separately, and then compared and integrated to create a ~ 3000 year record of past fire activity. The tree-ring record showed that from ad 1679 to 1879, there were frequent surface fires, while patches of high-severity fire occurred during widespread fire years. The alluvial record showed that a low- to moderate- and mixed-severity fire regime has likely been dominant over the past ~ 2600 calibrated calendar years before present, as shown by locally episodic deposition of charcoal-rich, fine-grained sediments. Radiocarbon dating suggested that in two stratigraphic sections, there was rapid deposition of several fine-grained sediment layers. One of these episodes occurred during the Medieval Climatic Anomaly (ad 900 - 1300). A charcoal-rich debris flow deposit in the oldest exposed part of the stratigraphic record dated to ~ 2600 calibrated calendar years before present. This event was potentially equivalent in magnitude to the debris-flow events following the recent wildfire in the study area, and is evidence of a high-severity fire that burned a large proportion of the study basin. The timing of this event coincides with a period of less frequent, yet more severe wildfires in a nearby lake sediment record, and is associated with the end of a Neoglacial period of cooler and wetter temperatures.

NOAA/IMPD web landing page for this fire history site is available at:
http://ncdc.noaa.gov/paleo/study/
16828
FHX filename: usvcm001.fhx

IMPD code: USVCM001

Name of site: Vallecito Country Market

Site code: VCM

Contributors: Bigio, E.R., Swetnam, T.W., Baisan, C.H.

Latitude: 37.437846 (WGS84)

Longitude: -107.561018 (WGS84)

Mean elevation: 2600 (meters)

Country: United States

State: Colorado

Region: San Juan Mountains

First year: 1502 AD

Last year: 2004 AD

Species name: Pinus ponderosa [PIPO]

Comments:
This site was chosen to correspond with alluvial-stratigraphy fire history sampling locations.

Fire History Graphs: Fire History Graphs illustrate specific years when fires occurred and how many trees were scarred. They are available in both PDF and PNG formats. The graphs consist of 2 parts, both of which show the X axis (time line) at the bottom with the earliest year of information on the left and the latest on the right. The Fire Index Plot is the topmost plot, and shows two variables: sample depth (the number of recording trees in each year) as a blue line along the left Y axis, compared with the percent trees scarred shown as gray bars along the right Y axis. Below, the Fire Chronology Plot consists of horizontal lines representing injuries by year on individual sampled trees. Symbols are overlain that denote the years containing the dendrochronologically-dated fire scars or injuries. The sample ID of each tree is displayed to the right of each line. The Composite Axis below represents the composite information from all individual series. The symbols used to represent the fire scars or injuries, and the filters used to determine the composite information, are shown in the legend. These graphs were created using the Fire History Analysis and Exploration System (FHAES). See https://www.frames.gov/partner-sites/fhaes/fhaes-home/ for more information.