Perpetuating old ponderosa pine

Resiliency of an Interior Ponderosa Pine Forest to Bark Beetle Infestations Following Fuel-Reduction and Forest-Restoration Treatments

“…Overall, higher levels of tree mortality occurred on LoD + B (18.8%) compared to HiD (5.7%) and LoD (4.6%) (Figure 1), and higher levels of bark beetle-caused tree mortality occurred on LoD + B (8.7%) compared to LoD (4.2%) (Figure 2). This is presumably due to the increased proportion of smaller-diameter trees on LoD [43], which tend to be of increased susceptibility to injury and mortality following prescribed fire [47,48,50]. To that end, no significant differences were observed between HiD and HiD + B, except for trees in the 54.7-cm diameter class for mortality attributed to all causes (Figure 1), bark beetles (Figure 2), and D. brevicomis (Figure 3).…”

“…Others have reported similar results described as a "U-shaped" distribution of tree mortality by tree diameter [49], which agrees with our observations at Blacks Mountain. Kolb et al [50] suggested that growth of large P. ponderosa can be accelerated by thinning, but warned that prescribed fire may predispose trees to increased levels of delayed mortality, often by bark beetles. In recent work at Blacks Mountain, Ritchie et al [51] reported tree vigor increased in thinned stands, but that an increase in the mortality of large trees occurred when thinning was followed by prescribed fire.…”

Effects of Prescribed Burning on Mortality and Resin Defenses in Old Growth Ponderosa Pine (Crater Lake, Oregon): Four Years of Post-Fire Monitoring

“…Following over one hundred years of fire exclusion, many stands have shown increases in tree density, fuel loading and wildfire severity, and overstory mortality compared to historic conditions (Parsons and DeBenedetti 1979;Agee 1993;Covington and Moore 1994;Sugihara et al 2006). Consequently, widespread interest exists in restoration treatments that mimic elements of the historic disturbance regime while maintaining the presence of dominant individual pines (Thomas and Agee 1986;Sackett and Haase 1998;Friederici 2003;Kolb et al 2007). Such treatments, including prescribed burning and mechanical fuel reduction, have shown considerable promise in the short term for reducing post-treatment wildfire intensity or severity (Pollet and Omi 2002;Finney et al 2005;Raymond and Peterson 2005;Stephens et al 2009).…”

Between-Year Breeding Dispersal by White-Headed Woodpeckers: A Caution About Using Color Bands to Estimate Survival

“…This will require time and protection from high severity disturbances (Harrod et al 2009, Franklin andJohnson 2012). In addition to loss due to wildfire, competition with mid-or understory-trees increases drought stress and makes them susceptible to bark beetle attack and mortality (Kolb et al 2007). Reducing tree density through thinning and/or prescribed fire reduces competition around large trees, which may improve vigor, and returns forest structure, and perhaps composition, closer to historical levels.…”

“…Prescribed fire can kill large trees that are intended to be saved by fuels treatment (Agee 2003, Brown et al 2004, Swezy and Agee 1991, Youngblood et al 2004. Even lowintensity prescribed burn may stress trees and attract bark beetles which can increase mortality of old trees for a number of years after the burn (Hood 2010, Kolb et al 2007, Swezy and Agee 1991, Thomas and Agee 1986. Current fuel loads may be too high to achieve mortality of fir without excessive mortality of large pine; even low-intensity prescribed fires may direct successional trends away from desired conditions by killing oldgrowth ponderosa pine (Swezy and Agee 1991).…”