DOE OSTI2013
In 1996, Swetnam and Baisan stated the following: “The 1977 La Mesa burn was a wake-up call to perhaps the most pressing forest health problem in Southwestern forests—historically anomalous, catastrophic wildfire in the ponderosa pine—created by many decades of fire exclusion.” However, the wake-up call was only momentary and was forgotten until the Dome Fire (1996), Oso Complex Fire (1998), and Cerro Grande Fire (2000) burned lands within the community of Los Alamos, Los Alamos National Laboratory (LANL), Bandelier National Monument (BNM), and Santa Fe National Forest (SFNF). After the Dome Fire, several initiatives were under way to understand the wildland-urban interface and the conditions that have brought the forests of the Pajarito Plateau dangerously close to multiple, large, and intense wildfires. After the Dome Fire, the Interagency Wildfire Management Team was formed, bringing together adjoining agencies to deal with the ever-increasing threat of conflagration that could result in loss of property and human life. This study is about the history before and after the La Mesa Fire—at the time, the first large wildfire on the Pajarito Plateau in over 80 years. It represents 37 years of research and observations that began when management of fire on the Pajarito Plateau was first being explored by BNM. It documents changes in vegetation composition since June 1977 and shows the progression of change in understanding fire’s essential place in the ecosystems of the Pajarito Plateau. The study began in 1975 and 1976, when Loren Potter and I examined previously burned areas to determine a fire frequency for the east Jemez Mountains. We had examined areas of 10 acres or more that had burned at various times, e.g., 1939, 1945, 1950, 1955, 1960, and 1976. A year and a half into the study, the La Mesa Fire ignited on Mesa del Rito, ultimately burning about 15,000 acres of BNM, SFNF, and LANL, including our established plots. After the fire, we set up 20- by 50-meter permanent plots along four ornithological transects established by ornithologist Roland Wauer. Wauer’s transects were mostly in ponderosa pine, with one in mixed conifer and one in the piñon-juniper woodland. Plots within the ponderosa pine were visited in 1977, 1978, 1985, 1992, 1998, 1999, 2010, 2011 and 2012. We mapped the standing trees, photographed each plot, and collected data on the understory components. Transects in the mixed conifer were visited in 1977, 1992, 1999, 2010 and 2012. Plots in the piñon-juniper were visited in 1977, 1999, and 2010 for taking photographs and data years after the fire. Additionally, plots were established in LANL Technical Area 49 as a control to post-fire seeding. We visited these plots in 1977, 1992, and 1998. Ironically, this study ends with another large fire burning over the plots we have followed all these years. In June 2011, the Las Conchas Fire became the largest fire in New Mexico’s history to that time and burned most of the area of the La Mesa Fire and the plots studied over the years. In this report, we summarize information about the vegetation changes within the boundaries of the La Mesa Fire. Thirty-seven years of observations and studies have provided long-term data related to regeneration of trees, water relations of grasses and pines, the influence of seeding with non-native grasses, pyrodendrochronology, and plant succession as related to fire.
54 ENVIRONMENTAL SCIENCES↗