Thinning decreases mortality and increases growth of Ponderosa pine in northeastern California

Abstract

Oventodted70-1090-year-old stands ofpondemsspineanmedium-tolow-qu were thinned in 1980 to 40.55. and 70 perant of n o d basal srea and c a n p a d to an unthinned cmuol. Mortality, diameter, and height in thesenorthem W o m i a stands wore m c a s u d annually from 1980 to 1987. After 8 years. mortality, primarily fmm mountain pine beetle (D~ndroclonrrr pondcrmae) and annosus rmt direare (Hcrcrobaridion mnosun), was reduced 100.95, and 86 percent relative to incming amounts of reserve basal area. Thinned stands averaged five times more cubic-foot volume gmwth than unthinned stands. More gmwth andlesr monality cwld result fmm mating similar stands elsewhere.

The effects of mechanical fuel reduction treatments on the activity of bark beetles (Coleoptera: Scolytidae) infesting ponderosa pine

“…In addition, we observed that many D. brevicomis and D. ponderosae attacks occurred immediately within the perimeter of the chipped area. Bark beetle outbreaks have been associated with high stand densities, presumably because below ground competition for nutrients and water lead to reductions in host vigor (Mitchell et al, 1983;McGregor et al, 1987;Amman et al, 1988;Fiddler et al, 1989). Thinning not only affects the vigor of residual trees by increasing growing space (Larsson et al, 1983;Mitchell et al, 1983), but the physical environment around individual trees.…”

The effectiveness of vegetation management practices for prevention and control of bark beetle infestations in coniferous forests of the western and southern United States

“…These results stress the importance of managing forest stands at appropriate spatial scales. Fiddler et al (1989) showed that thinning significantly reduced the amount of ponderosa pine mortality caused by mountain pine beetle in northeastern California. No tree mortality occurred in stands of <9 m 2 /ha of basal area, which agrees with the optimal stocking level of 11 m 2 /ha described by Oliver (1979Oliver ( , 1995.…”

Forest thinning and subsequent bark beetle-caused mortality in Northeastern California

“…Bark beetles play a crucial role in forest nutrient cycling and promote biodiversity by providing forage for avian and other species (Furniss and Carolin, 1977;Martin et al, 2006). At outbreak population levels, beetles can cause extensive tree mortality altering forest structure, reducing fiber productive capacity, and diminishing stand aesthetics (Cole and McGregor, 1988;Fiddler et al, 1989;Cochran and Barrett, 1998). Increases in surface fuel loadings also follow bark beetle-caused mortality (Jenkins et al, 2008;Klutsch et al, 2009).…”

“…Thinning studies in ponderosa pine forests consistently report that thinning reduced the density of bark beetle-caused mortality (trees ha −1 killed) or, where different thinning intensities were tested, areas with lower density had less percent mortality (trees ha −1 killed/trees ha −1 host available) compared to areas with higher density (Cole and McGregor, 1988;Fiddler et al, 1989;Schmid et al, 1994). Other studies, while not testing thinning practices directly, lend support to the thinning hypothesis by illustrating positive linear relationships found between ponderosa pine density and the density of MPB-caused mortality (Cole and McGregor, 1988;Fiddler et al, 1989;Oliver and Uzoh, 1997;Amman and Logan, 1998;Negron and Popp, 2004). Few studies have evaluated thinning efficacy in true fir forests.…”