Fire regimes of the piñon–juniper woodlands of Big Bend National Park and the Davis Mountains, west Texas, USA

Abstract

While piñon woodlands cover much of arid North America, surprisingly little is known about the role of fire in maintaining piñon forest structure and species composition. The lack of region-specific fire regime data for piñon–juniper woodlands presents a roadblock to managers striving to implement process-based management. This study characterized piñon–juniper fire regimes and forest stand dynamics in Big Bend National Park (BIBE) and the Davis Mountains Preserve of the Nature Conservancy (DMTNC) in west Texas. Mean fire return intervals were 36.5 and 11.2 years for BIBE and DMTNC, respectively. Point fire return intervals were 150 years at BIBE and 75 years at DMTNC. Tree regeneration in west Texas piñon–juniper woodlands occurred historically during favorable climatic conditions following fire years. The presence of multiple fire scars on our fire-scar samples and the multicohort stands of piñon suggested that low intensity fires were common. This study represents one of the few fire-scar-based fire regime studies for piñon–juniper woodlands. Our results differ from other studies in less topographically dissected landscapes that have identified stand-replacing fire as the dominant fire regime for piñon–juniper woodlands. This suggests that mixed-severity fire regimes are typical across southwestern piñon forests, and that topography is an important influence on fire frequency and intensity.

Fire regime shift linked to increased forest density in a piñon–juniper savanna landscape

“…piñon or juniper trees with multiple fire scars) has also been documented in different PJ types from southern Arizona (J. deppeana Steud. ; Leopold 1924) and west Texas (P. cembroides; Poulos et al 2009). The current study provides the best evidence of historical repeated low-severity fire in the PIED-JUSC PJ type.…”

“…Evidence might include multiple crossdated fire scars (on piñon and juniper trees) at multiple locations with age structure evidence that overstorey trees generally survived the fire (Baker and Shinneman 2004). The best evidence of low-severity fire in PJ ecosystems in the south-western USA may be from west Texas, where (Poulos et al 2009) found multiple fire-scarred piñon (Pinus cembroides Zucc.) in two mountain ranges, but fire extent and relationships between fire and PJ age structure are not clear.…”

Vegetation Dynamics on the Mountains and Plateaus of the American Southwest

“…However, neither study had confi rmed that unscarred trees had survived the fi res and were not of more recent origin. Another possible variation in the fi re regimes of persistent woodlands was described for two sites in southwestern Texas (Poulos et al 2009 ). It was determined that surface fi res had not spread far from Ponderosa Pine Forest into Pinyon-Juniper woodland (the terminology "Pinyon-Juniper woodland" here and hereafter follows its use by the authors of the study cited; in many cases it is equivalent to "Pinyon-Juniper persistent woodland").…”

Mapping fuels in the Chihuahuan Desert borderlands using remote sensing, geographic information systems, and biophysical modeling

“…Resource managers need tools for predicting, preventing, and suppressing future fires. Despite dramatically increased tree densities and fuel loads in Big Bend National Park (BB) in western Texas and in the Maderas del Carmen Protected Area (MC) in Coahuila, Mexico, since the decline in fire frequency since the 1940s (Poulos et al 2009), managers from these two protected areas lack fuel maps for adequately managing wildland fires. This study evaluates the potential of combining spectral, topographic, and field data for developing spatially explicit fuels maps for forest management in BB and MC to prioritize fuel reduction treatments that mitigate the risk of future catastrophic fire.…”