Analysis and out-year forecast of beetle, borer, and drought-induced tree mortality in California

Preisler, Haiganoush K.; Grulke, Nancy; Heath, Zachary; Smith, Sheri L.

doi:10.1016/j.foreco.2017.05.039

Cited by 36 publications

(19 citation statements)

References 20 publications

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“…In the Sierra Nevada, drought is common (Preisler et al . ), and may occur in half of all years (Grulke et al . ).…”

Section: Case Studiesmentioning

confidence: 97%

“…Over the last 5 years, the Sierra Nevada has experienced prolonged, exceptionally extreme drought, accompanied by loss of millions of trees to drought, bark beetle and wood borer (Preisler et al . ). Tree mortality was concentrated in the Transverse Range and the western Sierra Nevada, the areas of greatest O 3 exposure.…”

Section: Case Studiesmentioning

confidence: 99%

“…), increases successful bark beetle and wood borer attack (Preisler et al . ), weakens trees, increases probability of mortality and may increase susceptibility of air pollution‐affected forests to wildfires (Grulke et al . ).…”

Section: Organismal Effects Cascade To Community and Ecological Procementioning

confidence: 99%

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Ozone effects on plants in natural ecosystems

2019

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Tropospheric ozone (O 3 ) is an important stressor in natural ecosystems, with welldocumented impacts on soils, biota and ecological processes. The effects of O 3 on individual plants and processes scale up through the ecosystem through effects on carbon, nutrient and hydrologic dynamics. Ozone effects on individual species and their associated microflora and fauna cascade through the ecosystem to the landscape level. Systematic injury surveys demonstrate that foliar injury occurs on sensitive species throughout the globe. However, deleterious impacts on plant carbon, water and nutrient balance can also occur without visible injury. Because sensitivity to O 3 may follow coarse physiognomic plant classes (in general, herbaceous crops are more sensitive than deciduous woody plants, grasses and conifers), the task still remains to use stomatal O 3 uptake to assess class and species' sensitivity. Investigations of the radial growth of mature trees, in combination with data from many controlled studies with seedlings, suggest that ambient O 3 reduces growth of mature trees in some locations. Models based on tree physiology and forest stand dynamics suggest that modest effects of O 3 on growth may accumulate over time, other stresses (prolonged drought, excess nitrogen deposition) may exacerbate the direct effects of O 3 on tree growth, and competitive interactions among species may be altered. Ozone exposure over decades may be altering the species composition of forests currently, and as fossil fuel combustion products generate more O 3 than deteriorates in the atmosphere, into the future as well.

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“…In the Sierra Nevada, drought is common (Preisler et al . ), and may occur in half of all years (Grulke et al . ).…”

Section: Case Studiesmentioning

confidence: 97%

Section: Case Studiesmentioning

confidence: 99%

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Ozone effects on plants in natural ecosystems

2019

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“…Mortality triggered by the 2012-2016 drought was concentrated in pines (particularly ponderosa pine), drier locations (generally lower elevations and latitudes), and larger trees (Paz-Kagan et al 2017, Preisler et al 2017, Young et al 2017, Fettig et al 2019. A coarsescale analysis identified increased mortality in stands with more and/or larger trees, especially in dry sites, suggesting that water availability and competition for water play important roles in shaping susceptibility to bark beetles and ultimately tree mortality (Young et al 2017).…”

Section: Introductionmentioning

confidence: 99%

“…The 2012-2016 California drought may have been the most extreme in the last 1,000 yr (Griffin andAnchukaitis 2014, Robeson 2015), and an example of a "hot" drought where low levels of precipitation and high temperatures combine to increase drought intensity and amplify the ecological consequences (Overpeck 2013, Allen et al 2015). Among the drought's many effects was the initiation of a severe tree mortality event (Paz-Kagan et al 2017, Preisler et al 2017, Young et al 2017, Fettig et al 2019. By December 2017, it was estimated that 129 million trees had died across the state, with the highest concentration along the west slope of the southern and central Sierra Nevada (USDA 2017).…”

Section: Introductionmentioning

confidence: 99%

Forest structure and climate mediate drought‐induced tree mortality in forests of the Sierra Nevada,USA

Restaino

Young

Estes

et al. 2019

Ecological Applications

104

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Extreme drought stress and associated bark beetle population growth contributed to an extensive tree mortality event in California, USA, resulting in more than 129 million trees dying between 2012 and 2016. Although drought is an important driver of this mortality event, past and ongoing fire suppression and the consequent densification of forests may have contributed. In some areas, land management agencies have worked to reduce stand density through mechanical treatments and prescribed fire to restore forests to less dense, more open conditions that are presumably more resilient to disturbance and changing climate. Here, we evaluate if stand structural conditions associated with treated (e.g., thinned and prescribed burned) forests in the Sierra Nevada of California conferred more resistance to the bark beetle epidemic and drought event of 2012–2016. We found that, compared to untreated units, treated units had lower stand densities, larger average tree diameters, and greater dominance of pines (Pinus), the historically dominant trees. For all tree species studied, mortality was substantially greater in climatically drier areas (i.e., lower elevations and latitudes). Both pine species studied (ponderosa pine [Pinus ponderosa] and sugar pine [Pinus lambertiana]) had greater mortality in areas where their diameters were larger, suggesting a size preference for their insect mortality agents. For ponderosa pine, the tree species experiencing greatest mortality, individual‐tree mortality probability (for a given tree diameter) was significantly lower in treated stands. Ponderosa pine mortality was also positively related to density of medium‐ to large‐sized conspecific trees, especially in areas with lower precipitation, suggesting that abundance of nearby host trees for insect mortality agents was an important determinant of pine mortality. Mortality of incense cedar (Calocedrus decurrens) and white fir (Abies concolor) was positively associated with basal area, suggesting sensitivity to competition during drought, but overall mortality was lower, likely because the most prevalent and effective mortality agents (the bark beetles Dendroctonus brevicomis and D. ponderosae) are associated specifically with pine species within our study region. Our findings suggest that forest thinning treatments are effective in reducing drought‐related tree mortality in forests, and they underscore the important interaction between water and forest density in mediating bark beetle‐caused mortality.

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