DOI: 10.25921/2se3-1707
title: NOAA/WDS Paleoclimatology - Margolis fire data from Los Griegos Plot 2, northern New Mexico - IMPD USLGR002

description: Anthropogenic alteration of ecosystem processes confounds forest management and conservation of rare, declining species.  Restoration of forest structure and fire hazard reduction are central goals of forest management policy in the western United States, but restoration priorities and treatments have become increasingly contentious.  Numerous studies have documented changes in fire regimes, forest stand structure and species composition following a century of fire exclusion in dry, frequent-fire forests of the western U.S. (e.g., ponderosa pine and dry mixed-conifer).  In contrast, wet mixed-conifer forests are thought to have historically burned infrequently with mixed- or high-severity fire — resulting in reduced impacts from fire exclusion and low restoration need — but data are limited.  In this study we quantified the current forest habitat of the federally endangered, terrestrial Jemez Mountains salamander (Plethodon neomexicanus) and compared it to dendroecological reconstructions of historical habitat (e.g., stand structure and composition), and fire regime parameters along a gradient from upper ponderosa pine to wet mixed-conifer forests.  We found that current fire-free intervals in Jemez Mountains salamander habitat (116 - 165 years) are significantly longer than historical intervals, even in wet mixed-conifer forests.  Historical mean fire intervals ranged from 10 to 42 years along the forest gradient.  Low-severity fires were historically dominant across all forest types (92 of 102 fires).  Although some mixed- or high-severity fire historically occurred at 67% of the plots over the last four centuries, complete mortality within 1.0 ha plots was rare, and asynchronous within and among sites.  Climate was an important driver of temporal variability in fire severity, such that mixed- and high-severity fires were associated with more extreme drought than low-severity fires.  Tree density in dry conifer forests historically ranged from open (90 trees ha-1) to moderately dense (400 trees ha-1), but has doubled on average since fire exclusion.  Infill of fire-sensitive tree species has contributed to the conversion of historically dry mixed-conifer to wet mixed-conifer forest.  We conclude that low-severity fire, which has been absent for over a century, was a critical ecosystem process across the forest gradient in Jemez Mountains salamander habitat, and thus is an important element of ecosystem restoration, resilience, and rare species recovery.
description: This site was sampled as part of a project to reconstruct the fire history in habitat of the Jemez Mountain Salamander in northern New Mexico. 

Sample_storage_location: University of Arizona Laboratory of Tree-Ring Research, 1215 E Lowell St., Tucson, Arizona, 85721
Dating_method: crossdated
Area_sampled [hectares]: 1

FHX File Header: For additional information, see the header of this datasets FHX file, uslgr002.fhx. 

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.fhaes.org/ and  https://doi.org/10.5281/zenodo.593323 for more information.