Mesa Acuña - MXMA-001 Yocom, Larissa L.; Fulé, Peter Z. Dating method: crossdated Sample storage location: Northern Arizona University, Flagstaff, AZ Reference: Yocom, L.L., P.Z. Fulé, P.M. Brown, J. Cerano, J. Villanueva-Díaz, D.A. Falk, and E. Cornejo-Oviedo. 2010. El Niño-Southern Oscillation effect on a fire regime in northeastern Mexico has changed over time. Ecology 91:1660-1671. http://www.jstor.org/stable/25680407 Abstract: The El Niño Southern Oscillation (ENSO) is a climate-forcing mechanism that has been shown to affect precipitation and the occurrence of wildfires in many parts of the world. In the southern United States and northern Mexico, warm events (El Niño) are associated with moist winter conditions and fewer fires, while cool events (La Niña) tend to favor dry winters and more fires. We tested this relationship in a region of northeastern Mexico by characterizing the historical fire regime and climatic influences. Fire regimes were reconstructed from fire-scar samples collected from 100 trees in three high-elevation sites on Pena Nevada in southern Nuevo Leon. The sites were ~25 ha each, and the site centers were ~1 km apart. The earliest recorded fire occurred in 1521 and the time period we used for analysis was 1645-1929. The sites were characterized by frequent surface fires before the 1920s. In the three sites, mean fire intervals ranged from 8.6 to 9.6 years (all fires) and 11.9 to 18.6 years (fires that scarred >25% of recording trees). The per-tree mean fire return interval was 17 years, and all three sites burned in the same year seven times between 1774 and 1929. After 1929, fires were nearly eliminated in all sites, likely due to human causes. We found a temporal change in the association between ENSO events and fires; before the 1830s La Niña events were significantly associated with fire years, while after the 1830s this association was not significant. In 1998, when the most severe El Niño event of the past century occurred, the three sites experienced severe, stand-replacing fires that killed many trees that had survived multiple surface fires in the past. Prior to the 1830s, fires tended to occur during dry La Niña years, but since then both La Niña and El Niño have been associated with dry years in this region, especially during the last three decades. This result suggests that ENSO effects have changed over time in this location and that phases of ENSO are not consistent indicators of precipitation, fire occurrence, or fire behavior in this area of northeastern Mexico. Reference: Yocom Kent, L.L., P.Z. Fulé, P.M. Brown, J. Cerano, E. Cornejo-Oviedo, C. Cortés Montaño, S.A. Drury, D.A. Falk, J. Meunier, H.M. Poulos, C.N. Skinner, S.L. Stephens, J. Villanueva-Díaz. 2017. Climate drives fire synchrony but local factors control fire regime change in northern Mexico. Ecosphere 8(3): Article e01709. Abstract: The occurrence of wildfire is influenced by a suite of factors ranging from “top-down” influences (e.g., climate) to “bottom-up” localized influences (e.g., ignitions, fuels, and land use). We carried out the first broad-scale assessment of wildland fire patterns in northern Mexico to assess the relative influence of top-down and bottom-up drivers of fire in a region where frequent fire regimes continued well into the 20th century. Using a network of 67 sites, we assessed (1) fire synchrony and the scales at which synchrony is evident, (2) climate drivers of fire, and (3) asynchrony in fire regime changes. We found high fire synchrony across northern Mexico between 1750 and 2008, with synchrony highest at distances <400 km. Climate oscillations, especially El Niño-Southern Oscillation, were important drivers of fire synchrony. However, bottom-up factors modified fire occurrence at smaller spatial scales, with variable local influence on the timing of abrupt, unusually long fire-free periods starting between 1887 and 1979 CE. Thirty sites lacked these fire-free periods. In contrast to the neighboring southwestern United States, many ecosystems in northern Mexico maintain frequent fire regimes and intact fire–climate relationships that are useful in understanding climate influences on disturbance across scales of space and time. Related ITRDB chronology: MEXI095 NOAA/IMPD web landing page for this fire history site is available at: https://ncdc.noaa.gov/paleo/study/21571 NOAA/IMPD DIF and JSON metadata records for this fire history site are available at: https://www1.ncdc.noaa.gov/pub/data/metadata/published/paleo/dif/xml/noaa-fire-21571.xml and https://www1.ncdc.noaa.gov/pub/data/metadata/published/paleo/json/noaa-fire-21571.json FHX filename: mxma-001.fhx IMPD code: MXMA-001 Name of site: Mesa Acuña Site code: MA Contributors: Yocom, Larissa L.; Fulé, Peter Z. Latitude: 23.78 (WGS84) Longitude: -99.86 (WGS84) Mean elevation: 3200 (meters) Country: Mexico State: Nuevo León Region: Sierra Madre Oriental First year: 1526 AD Last year: 2006 AD Species name: Pinus hartwegii [PIHR], [ PSME] Funding agency names and grant numbers: National Science Foundation DEB-0640351 Comments: This site was sampled as part of a project to reconstruct historical fire regimes in northeastern Mexico. Ring-boundary fire scars were assigned to the subsequent calendar year. Yocom fire data from Mesa Acuña, Sierra Madre Oriental, Nuevo León, Mexico - IMPD MXMA-001 https://www.ncdc.noaa.gov/paelo/study/21571 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://www.fhaes.org for more information.