San Francisco Peaks (West) - USSPW001 Additional Site Information Thomas A. Heinlein, Margaret M. Moore, Peter Z. Fulé, W. Wallace Covington Dating Method: Crossdated Sample Storage Location: Northern Arizona University (contact Pete.Fule@nau.edu) Reference: Heinlein, T.A., M.M. Moore, P.Z. Fulé, and W.W. Covington. 2005. Fire history and stand structure of two ponderosa pine-mixed conifer sites: San Francisco Peaks, Arizona, USA. International Journal of Wildland Fire. 14:307-320. doi:10.1071/WF04060 Abstract: We reconstructed historical fires regimes and contemporary and historical stand structures in the drier mixed conifer forests on the San Francisco Peaks in northern Arizona, USA. Thirty-four fire-scarred specimens recorded 256 fires from the EAST and WEST study sites. Fires were recorded between 1739 and 1903 for the EAST site and between 1548 and 1947 for the WEST site. The mean fire return interval (MFI: >= 25% scarred) for the period 1690-1892 was 10 years with a range of 3 to 21 years for the EAST site. The WEST site MFI (period 1612-1876) was 9 years with a range of 3 to 21 years. Seasonal patterns of fire occurrence showed that the majority of fires burned during the summer months. Fire interval (years) means, variances, and distributions between the EAST and WEST sites were not statistically different from one another for the common analysis period of 1690-1876. Historically, both the EAST and WEST sites were dominated by ponderosa pine, with scattered individuals of Douglas-fir, limber pine, and white fir, with tree densities that ranged from 44 to 60 trees per hectare (TPH). Current forest composition has shifted from fire-tolerant ponderosa pine to less fire-tolerant, more shade-tolerant species, with tree densities ranging from 1,516 to over 1,700 TPH. We suggest that the dramatic structural changes recorded at our study sites occurred since fire regime disruption. 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.