Probability of infestation and extent of mortality associated with the Douglas-fir beetle in the Colorado Front Range

Negrón, José F.

doi:10.1016/s0378-1127(97)00319-8

Cited by 77 publications

(101 citation statements)

References 25 publications

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“…As a result we observed an increase in the proportion of ponderosa pine in these stands. Species composition and tree density and basal area levels in our study sites were similar to those found in ponderosa pine/Douglas-fir forests in other Colorado Front Range studies, particularly in north-facing aspects [22,31]. Species composition and stand structure of our heavily defoliated sites were not significantly different than in lightly defoliated sites, though other studies found that species composition and stand structure do contribute to DFTM susceptibility [32,33].…”

Section: Discussionsupporting

confidence: 83%

“…By the time our sites were sampled, DFB caused mortality in both heavily and lightly defoliated stands. This mortality was concentrated in the larger diameter classes, portraying the preference of the insect for larger diameter trees [16,20,22]. Douglas-fir tussock moth populations have a propensity to concentrate around initial infestation sites [36,37], so the distribution of DFTM-related tree mortality is probably associated with spatial location of early infestation foci.…”

Section: Discussionmentioning

confidence: 99%

“…These conditions result in reduced susceptibility to DFTM until surviving and recruiting understory trees grow to susceptible stages. However, depending on the density of surviving large Douglas-fir trees, stands may be susceptible to future DFB outbreaks [16,20,22]. The dispersal ability of the DFB results in larger landscapes being affected, resulting in vegetation mosaics composed of smaller trees reducing susceptibility to DFB outbreaks but maintaining stand conditions susceptible to DFTM.…”

Section: Discussionmentioning

confidence: 99%

“…Eruptive populations usually develop after fires, blowdowns, or defoliation events [16,17]. Outbreak populations of DFB cause extensive tree mortality across the central and Northern Rockies and the Pacific Northwest [18][19][20][21]. Douglas-fir beetle attacks primarily large diameter trees in highly stocked stands dominated by Douglas-fir, especially trees with reduced growth [16,22].…”

mentioning

confidence: 99%

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Douglas-Fir Tussock Moth- and Douglas-Fir Beetle-Caused Mortality in a Ponderosa Pine/Douglas-Fir Forest in the Colorado Front Range, USA

Negrón

Lynch

Schaupp³

et al. 2014

Forests

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An outbreak of the Douglas-fir tussock moth, Orgyia pseudotsugata McDunnough, occurred in the South Platte River drainage on the Pike-San Isabel National Forest in the Colorado Front Range attacking Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco. Stocking levels, species composition, and tree size in heavily and lightly defoliated stands were similar. Douglas-fir tussock moth defoliation resulted in significant Douglas-fir mortality in the heavily defoliated stands, leading to a change in dominance to ponderosa pine, Pinus ponderosa Lawson. Douglas-fir beetle, Dendroctonus pseudotsuqae Hopkins, populations increased following the defoliation event but caused less mortality, and did not differ between heavily and lightly defoliated stands. Douglas-fir tussock moth-related mortality was greatest in trees less than 15 cm dbh (diameter at 1.4 m above the ground) that grew in suppressed and intermediate canopy positions. Douglas-fir beetle-related mortality was greatest in trees larger than 15 cm dbh that grew in the dominant and co-dominant crown positions. Although both insects utilize Douglas-fir as its primary host, stand response to infestation is different. The extensive outbreak of the Douglas-fir tussock OPEN ACCESSForests 2014, 5 3132 moth followed by Douglas-fir beetle activity may be associated with a legacy of increased host type growing in overstocked conditions as a result of fire exclusion.

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Section: Discussionsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Douglas-Fir Tussock Moth- and Douglas-Fir Beetle-Caused Mortality in a Ponderosa Pine/Douglas-Fir Forest in the Colorado Front Range, USA

Negrón

Lynch

Schaupp³

et al. 2014

Forests

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“…Statistical analyses by means of regression models corroborate the relevance of the local environment and individual tree characteristics as predictors of insect-related tree mortality (e.g., Negrón et al, 2001;Doak, 2004;Fabrika and Vaculčiak, 2009: SIBYLA). Nonetheless, statistical models were also developed at the stand level, using multiple linear or logistic regression as well as classification and regression tree models (Negrón, 1998;Eisenbies et al, 2007;Pothier and Mailly, 2007). To stratify stand level estimates and identify weakened or preferred host individuals, tree characteristics and configuration are frequently used (Lexer and Hönninger, 1998;Seidl et al, 2007: PICUS;Ager et al, 2007).…”

Section: Impactmentioning

confidence: 99%

Modelling natural disturbances in forest ecosystems: a review

Seidl

Fernandes

Fonseca

et al. 2011

Ecological Modelling

343

219

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Predictors of Ips confusus Outbreaks During a Record Drought in Southwestern USA: Implications for Monitoring and Management

Santos

Whitham

2009

Environmental Management

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In many ecosystems the effects of disturbance can be cryptic and disturbance may vary in subtle spatiotemporal ways. For instance, we know that bark beetle outbreaks are more frequent in temperate forests during droughts; however, we have little idea about why they occur in some locations and not others. Understanding biotic and abiotic factors promoting bark beetle outbreaks can be critical to predicting and responding to pest outbreaks. Here we address the environmental factors which are associated with Ips confusus outbreaks during the 2002 widespread drought within the distribution range of pinyon pine woodlands in Arizona. We used univariate statistics to test if whether tree characteristics, other herbivores, stand properties, soil type, wind, and topography were associated with I. confusus outbreak, and logistic regression to create a predictive model for the outbreaks. We found that I. confusus attacks occur in low elevation stands on steeper slopes, where favorable winds for I. confusus dispersion occur. I. confusus select larger trees, in high density stands with understory shrubs that exhibit phenotypic traits characteristic of resistance to stem-boring moths. The model was highly accurate, and explained 95% of the variability in occurrence (98% of the absences and 95% of the presences). Accurate prediction of the impacts of disturbance allow us to anticipate, minimize or mitigate for and eventually counteract its effects, especially those affecting diversity and ecosystem function. Identification of outbreak risk areas can guide regional and national management towards the reduction of infestation risk and enhancing conservation of pinyon-juniper woodlands.

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Probability of infestation and extent of mortality associated with the Douglas-fir beetle in the Colorado Front Range

Cited by 77 publications

References 25 publications

Douglas-Fir Tussock Moth- and Douglas-Fir Beetle-Caused Mortality in a Ponderosa Pine/Douglas-Fir Forest in the Colorado Front Range, USA

Douglas-Fir Tussock Moth- and Douglas-Fir Beetle-Caused Mortality in a Ponderosa Pine/Douglas-Fir Forest in the Colorado Front Range, USA

Modelling natural disturbances in forest ecosystems: a review

Predictors of Ips confusus Outbreaks During a Record Drought in Southwestern USA: Implications for Monitoring and Management

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