AmeriDendro 2013 registration is open: follow the link on the Overview page.
Collapse of frequent fire regime linked to increased tree density in a piñon-juniper landscape, New Mexico, USA
Presented by Dr. Ellis MARGOLIS on 14 May 2013 from 10:10 to 10:30
Type: Oral Presentation
Session: Fire Ecology I
Track: Fire ecology
Piñon-juniper (PJ) fire regimes are described as infrequent and high severity, but data for PJ savannas are lacking. The goal of my research was to reconstruct the history of fire and forest structure on a 30,000 ha PJ-dominated, savanna landscape. I crossdated 112 fire-scarred trees (8% Juniperus scopulorum, 17% Pinus edulis, and 74% P. ponderosa) containing 630 fire scars that burned during 87 unique fire years (1547-1899). Mean fire interval was 7.8 years for fires recorded at > 2 sites (separated by 7 km), and 23.7 years for fires recorded at over half of the sites. Evidence of high severity fire (e.g., even-aged stands or fire-killed snags or logs) was not observed. Frequent, low-severity fires historically maintained low tree densities across what was a PJ–PIPO savanna landscape and late 19th century fire cessation, initiated by overgrazing, was the primary driver of current high tree densities (> 880 trees/ha).