Full Citation: Brown, Peter M.; Wu, Rosalind. 2005. Climate and disturbance forcing of episodic tree recruitment in a southwestern ponderosa pine landscape. Ecology 86(11):3030-3038.
External Identifier(s): 10.1890/05-0034 Digital Object Identifier
Location: Archuleta Mesa, Colorado, U.S.
Ecosystem types: Ponderosa pine ecosystem; Gambel’s oak ecosystem; piñon-juniper; Douglas-fir
Southwest FireCLIME Keywords: None
Tags: Fuel moisture
FRAMES Keywords: ENSO - El Nino Southern Oscillation, fire regimes, Pinus ponderosa, ponderosa pine, population dynamics, Colorado, dendroecology, drought, tree recruitment, tree demography, age classes, bark, climatology, coniferous forests, crown scorch, dendrochronology, disturbance, fire frequency, fire injury, fire management, forest management, fuel accumulation, ignition, Juniperus osteosperma, Juniperus scopulorum, mortality, overstory, plant communities, plant growth, plant physiology, population density, Pseudotsuga menziesii, Douglas-fir, Quercus gambelii, rate of spread, regeneration, seed germination, seedlings, statistical analysis, surface fires, wildfires

Climate and disturbance forcing of episodic tree recruitment in a southwestern ponderosa pine landscape

Peter M. Brown, Rosalind Wu


Summary - what did the authors do and why?

The authors used tree-ring chronologies to compare timing of historic ponderosa pine recruitment to tree-ring based climate reconstruction variables, including annual precipitation, PDSI, Southern Oscillation Index, and Niño3 sea surface temperature (SST) index, and also fire disturbance to understand how both climate and fire have influenced current forest stand structure.


Publication findings:

The authors linked a large period of megadrought in the 1580’s to high mortality of ponderosa pine as no trees predated this event, and seedlings nearest the time of the event grew especially slowly. Due to the lack of surviving trees, there is no evidence of fire-caused mortality during this event.

Pulses of regeneration occurred during several periods of increased moisture; however, the authors suggest it was the absence of fire that allowed may trees to survive into adulthood and not due to episodic mortality caused by fire or other disturbance. Climate change likely affected fuel conditions that were less favorable for burning during these fire?quiescent periods allowing fuels to build up until drier years when synchronous regional fires occurred. This pattern has been commonly attributed to the ENSO cycle with wet El Niño years followed by dry La Niña years.

Climate and Fire Linkages

Climate change likely affected fuel conditions that were less favorable for burning during these fire?quiescent periods allowing fuels to build up until drier years when synchronous regional fires occurred. This pattern has been commonly attributed to the ENSO cycle with wet El Niño years followed by dry La Niña years.

Successful regeneration pulses occurred when conditions were less conducive to fire, such as during periods of increased precipitation or during cycles of El Niño, which are typically wet. Synchronous fire years typically occurred during La Niña years following a one to three year wet period.

Fire and Ecosystem Effects Linkages

The authors suggest that even-aged cohorts of ponderosa pine are not the result of severe crown fire, but long fire-free intervals that allowed seedlings to survive long enough to resist fire-induced mortality.

Pulses of regeneration occurred during several periods of increased moisture; however, the authors suggest it was the absence of fire that allowed may trees to survive into adulthood and not due to episodic mortality caused by fire or other disturbance. Climate change likely affected fuel conditions that were less favorable for burning during these fire?quiescent periods allowing fuels to build up until drier years when synchronous regional fires occurred. This pattern has been commonly attributed to the ENSO cycle with wet El Niño years followed by dry La Niña years.