Holocene fire-related alluvial-fan deposition and climate in ponderosa pine and mixed-conifer forests, Sacramento Mountains, New Mexico, USA

Abstract

We employed 14C dating of alluvial-fan deposits in ponderosa pine and mixed-conifer forests of the Sacramento Mountains, New Mexico to document Holocene fires and related geomorphic impacts. Rapid aggradation by charcoal-rich debris flows occurred in the middle Holocene (5800—4200 cal. yr BP), indicating episodic sedimentation following severe fires. Fire-related deposition virtually ceased ~4200 cal. yr BP, with most fan deposits indicating slower aggradation with cumulic soil development until 1800 cal. yr BP. From 1800 to 500 cal. yr BP, fire-related sedimentation increased again, although not to middle Holocene levels. A peak in fire-related sedimentation c . 650 cal. yr BP corresponds to widespread severe drought in the southwestern USA. Limited fire-related sedimentation is evident from 500 to 100 cal. yr BP, consistent with `Little Ice Age' climate and tree-ring records indicating frequent low-severity fires, although at least one severe fire burned in this interval. Increased fire-related sedimentation corresponds to generally warmer conditions. We infer that higher climate variability was also involved, including multidecadal wet periods that limited surface fires and allowed stand densities to increase, promoting severe fires in subsequent severe droughts. Fire has contributed significantly to Holocene valley aggradation. Local fan channel incision followed recent fires, but major nineteenth—twentieth century arroyo cutting appears unprecedented during the Holocene.

Late Holocene development of a Norwegian alpine alluvial fan affected by proximal glacier variations, episodic distal undercutting, and colluvial activity

“…Alluvial fans -their process domains, sedimentology, stratigraphy, and models of development -have been researched in a variety of arctic-alpine, temperate, and tropical environments (e.g., Hooke, 1967;Bull, 1977;Boothroyd and Nummendal, 1978;Kesel and Spicer, 1985;Rachocki and Church, 1990;Catto, 1993;Blair and McPherson, 1994;Blair, 1999aBlair, , 1999bBlair, , 2001Anderson et al, 2000;Frechette and Meyer, 2009;Giles et al, 2010). It is widely recognised that fans may be predominantly fluvial or colluvial in origin and that the extent to which these different types of geomorphic activity dominate fan development may change over time.…”

Forest responses to increasing aridity and warmth in the southwestern United States

“…For example, tree-ring data suggest that regionally extensive droughts in the late 1200s and late 1500s CE caused increased tree mortality throughout the SW US (3). Additionally, recent sedimentary charcoal studies identified cases of unusually severe wildfire events (but of unknown extent) in some SW forests dating to the 1200s CE period, and during warm mid-Holocene periods (32). More recently, mortality of many SW tree species occurred during the severe drought of the 1950s (3,18).…”

“…Historical ecology studies of SW forests show extensive wildfires and bark-beetle infestations to be natural disturbance processes linked to climate variability (3,(31)(32)(33)(34). For example, tree-ring data suggest that regionally extensive droughts in the late 1200s and late 1500s CE caused increased tree mortality throughout the SW US (3).…”

Fire history on the California Channel Islands spanning human arrival in the Americas

“…Charcoal in fluvial sediments cannot be interpreted in this way, as both deposition rates and sediment textures may vary significantly. Despite these challenges, reconstructing fire history from these environments has advantages, in particular being able to directly connect the charcoal record to geomorphic responses to fire [32][33][34][35][104][105][106]. Streams and floodplains are also landscape systems that humans would have regularly used (and indeed often also contain archaeological materials).…”