Spatiotemporal variability of fire regimes in adjacent Native American and public forests, New Mexico, USA

Statistical descriptions of reconstructed fire regimes are often extrapolated from a composite of small forest stands to represent extensive geographical areas. However, statistical properties of fire regimes are scale-dependent, thus causing some extrapolations from fine scale to coarse scale and comparisons between fire-scar-based reconstructions to be inappropriate. We assessed landscape fire regimes of the Sacramento Mountains, in southern New Mexico, using dendrochronological methods and a variety of fire statistics and analysis filters. We reconstructed historical and recent fire regimes for the Mescalero Apache Tribal Lands (MATL) at tree and site scale (25 ha). We then estimated the Sacramento Mountains historical and recent fire regimes by combining paleo fire data from this study with published data from the adjacent Lincoln National Forest (LNF). We applied filters to provide fire statistics that are relatively unbiased to the different spatial measurement extent of the studies. This is the first study to assess fire regime in the MATL over multiple spatial and temporal scales. The results show that frequent surface fires occurred at all scales in the Sacramento Mountains until fire was excluded from the landscape in the early 1900s. Historical fires were found to be synchronous with drought years, typically La Nina events, and often preceded by wet years. We did not find evidence supporting differences in fire regimes between the MATL and the LNF, suggesting that fire cessation following intensive Euro-American settlement was widespread. The interruption of frequent surface fires, together with other changes in forest structure and climate, pose a significant threat to sustainability of forest ecosystems on Native American tribal lands.