Mount Lemmon - USLEM001 Additional Site Information Henri D. Grissino-Mayer, Kiyomi Morino, Christopher H. Baisan, Thomas W. Swetnam Dating Method: Crossdated Sample Storage Location: Laboratory of Tree-Ring Research, University of Arizona, Tucson, AZ. Reference: Baisan, C.H., Morino, K.A., Grissino-Mayer, H.D. and T.W. Swetnam. 1998. Final Report: Fire History in ponderosa pine and mixed-conifer forests of the Santa Catalina Mountains: 15 pages. Swetnam, T. W. and C. H. Baisan. 2003. Tree-ring reconstructions of fire and climate history in the Sierra Nevada and Southwestern United States. In: T. Veblen, W. Baker, G. Montenegro, and T. W. Swetnam, editors. Fire and Climatic Change in Temperate Ecosystems of the Western Americas. Ecological Studies Vol. 160. Springer, New York: 158-195. Abstract: (Baisan et al., 1998) Eighty five fire-scarred wood sections collected within five pine and mixed-conifer stands were analyzed to determine pre-1900 fire regime characteristics in the upper elevations of the Catalina Mountains. Fire frequencies were similar at all elevations when all fire events were analyzed, with a mean fire intervals (MFI) of 4 to 6 years between occurrences. However, when only more extensive fires were included MFI varied with elevation and aspect ranging from 7 years at 7,000' to 10 years at 9,000' on northeast aspects. Fire frequency appeared to decline again below 7,000', however this is most likely an artifact of small sample size. Fire seasonality analysis determined that fires typically burned between late April and mid July. Fire sizes were variable, however some fires appear to have burned through large portions of the forested zone and may have exceeded 20,000 acres in size. Fires burning more than 1,000 acres appear to have been common. A change in the spatial, seasonal, and temporal character of the reconstructed fire regime at ca. 1800 may indicate a change in fire-climate relationships in the region. 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 http://frames.nbii.gov/fhaes/ for more information.