Tree mortality patterns following prescribed fires in a mixed conifer forest

2006 ◽  
Vol 36 (12) ◽  
pp. 3222-3238 ◽  
Author(s):  
Leda Kobziar ◽  
Jason Moghaddas ◽  
Scott L Stephens
Keyword(s):  
Sierra Nevada ◽  
Ponderosa Pine ◽  
Tree Mortality ◽  
Fire Behavior ◽  
Mortality Rates ◽  
Fire Intensity ◽  
Conifer Forest ◽  
Mixed Conifer ◽  
Mixed Conifer Forest ◽  
White Fir

During the late fall of 2002 we administered three burns in mixed conifer forest sites in the north-central Sierra Nevada. Eight months later we measured fire-induced injury and mortality in 1300 trees. Using logistic regression, an array of crown scorch, stem damage, fuels, and fire-behavior variables were examined for their influence on tree mortality. In Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), white fir (Abies concolor (Gord. & Glend.) Lindl.), and incense cedar (Calocedrus decurrens (Torr.) Florin), smaller trees with greater total crown damage had higher mortality rates. Smaller stem diameters and denser canopies predicted mortality best in ponderosa pine (Pinus ponderosa Dougl. ex P. Laws. & C. Laws). Duff consumption and bark char severity increased model discrimination for white fir and incense cedar and California black oak (Quercus kelloggii Newberry), respectively. In tanoak (Lithocarpus densiflorus (Hook. & Arn.) Rehd.), greater total crown damage in shorter trees resulted in higher mortality rates. Along with tree diameter and consumption of large (>7.6 cm diameter at breast height, DBH) rotten downed woody debris, fire intensity was a significant predictor of overall tree mortality for all species. Mortality patterns for white fir in relation to crown damage were similar among sites, while those for incense cedar were not, which suggests that species in replicated sites responded differently to similar burns. Our results demonstrate actual fire-behavior data incorporated into mortality models, and can be used to design prescribed burns for targeted reduction of tree density in mixed conifer forests.

Tree mortality from fire and bark beetles following early and late season prescribed fires in a Sierra Nevada mixed-conifer forest

2006 ◽  
Vol 232 (1-3) ◽  
pp. 36-45 ◽  
Author(s):  
Dylan W. Schwilk ◽  
Eric E. Knapp ◽  
Scott M. Ferrenberg ◽  
Jon E. Keeley ◽  
Anthony C. Caprio
Keyword(s):  
Sierra Nevada ◽  
Bark Beetles ◽  
Tree Mortality ◽  
Prescribed Fires ◽  
Conifer Forest ◽  
Mixed Conifer ◽  
Late Season ◽  
Mixed Conifer Forest

scholarly journals Historical and current landscape-scale ponderosa pine and mixed conifer forest structure in the Southern Sierra Nevada

Ecosphere ◽  
2015 ◽  
Vol 6 (5) ◽  
pp. art79 ◽  
Author(s):  
Scott L. Stephens ◽  
Jamie M. Lydersen ◽  
Brandon M. Collins ◽  
Danny L. Fry ◽  
Marc D. Meyer
Keyword(s):  
Sierra Nevada ◽  
Forest Structure ◽  
Ponderosa Pine ◽  
Landscape Scale ◽  
Conifer Forest ◽  
Mixed Conifer ◽  
Mixed Conifer Forest

Post-fire epicormic branching in Sierra Nevada Abies concolor (white fir)

2006 ◽  
Vol 15 (1) ◽  
pp. 31 ◽  
Author(s):  
Chad T. Hanson ◽  
Malcolm P. North
Keyword(s):  
Sierra Nevada ◽  
Fire Suppression ◽  
Large Diameter ◽  
Abies Concolor ◽  
Conifer Forest ◽  
Mixed Conifer ◽  
Diameter Class ◽  
Mixed Conifer Forest ◽  
White Fir ◽  
Epicormic Branching

In California’s mixed-conifer forest, which historically had a regime of frequent fires, two conifers, Sequoiadendron giganteum and Pseudotsuga menziesii, were previously known to produce epicormic sprouts from branches. We found epicormic branching in a third mixed-conifer species, Abies concolor, 3 and 4 years after a wildfire in the central Sierra Nevada Mountains of California. Sprouting occurred only from the boles. We investigated (1) whether the degree of crown loss and the extent of epicormic branching were independent; and (2) whether epicormic branching differed by tree size. The vertical extent of epicormic foliage increased with increasing severity of crown loss. There was a significantly greater proportion of large diameter-class (>50 cm diameter at breast height [dbh]) trees with epicormic branching than small/medium diameter-class (25–50 cm dbh) trees. These results suggest large diameter Abies concolor may survive high levels of crown loss, aided by crown replacement through epicormic branching, but that reiterative green foliage may not appear for up to 3 years after fire damage. If this response is widespread, it would suggest some ‘dying’ trees logged under current salvage guidelines could survive, and that higher-intensity fire may substantially reduce the density of small post-fire suppression white fir, while retaining many larger overstory trees.

scholarly journals Responses of soil physico-chemical properties to combustion: a space for time substitution study to infer how changes in climate are likely to affect response of topsoil to fires

2016 ◽  
Author(s):  
Samuel N. Araya ◽  
S. Mercer Meding ◽  
Asmeret Asefaw Berhe
Keyword(s):  
Climate Change ◽  
Sierra Nevada ◽  
Chemical Properties ◽  
Fire Intensity ◽  
Conifer Forest ◽  
Mixed Conifer ◽  
Mixed Conifer Forest ◽  
Physico Chemical ◽  
Temperature Ranges ◽  
Aggregate Strength

Abstract. Fire is a common ecosystem perturbation that affects many soil properties. As global fire regimes continue to change with climate change, we investigated the effect of fire heating temperatures on the physical and chemical properties of soils across a climosequence transect along the Western slope of the Sierra Nevada that spans from 210 to 2865 m.a.s.l. All the soils we studied were formed on a granitic parent material and have sign ificant differences in soil organic matter (SOM) concentration and mineralogy owing to the effects of climate on soil development. The dominant vegetation from lowest to highest elevation across the transect range from oak woodland, oak/mixed-conifer forest, mixed-conifer forest and subalpine mixed-conifer forest. Topsoils (0–5 cm depth) from the Sierra Nevada climosequence were heated in a muffle furnace at six set temperatures that cover the range of major fire intensity classes (150, 250, 350, 450, 550 and 650 °C). We determined the effects of fire heating temperature on soil aggregate strength, aggregate size distribution, specific surface area (SSA), mineralogy, pH, cation exchange capacity (CEC), and carbon (C) and nitrogen (N) concentrations. With increase of temperature, we found significant reduction of total C, N and CEC. Aggregate strength also decreased with further implications for loss of C protected inside aggregates. Soil pH and SSA increased with increase in temperature. Most of the statistically significant changes (p < 0.05) occurred at temperature ranges of 350 to 450 °C. We observed relatively smaller changes at typical temperature ranges of prescribed fires (i.e. less than 250 °C). This study identifies critical combustion temperature thresholds for significant physico-chemical changes in soils that developed under different climate regimes, allowing inferences for how soils are likely to respond to different fire intensities under anticipated climate change scenarios.

scholarly journals Armillaria Root Disease-Caused Tree Mortality following Silvicultural Treatments (Shelterwood or Group Selection) in an Oregon Mixed-Conifer Forest: Insights from a 10-Year Case Study

2010 ◽  
Vol 25 (3) ◽  
pp. 136-143 ◽  
Author(s):  
Gregory M. Filip ◽  
Helen M. Maffei ◽  
Kristen L. Chadwick ◽  
Timothy A. Max
Keyword(s):  
Ponderosa Pine ◽  
Group Selection ◽  
Tree Mortality ◽  
Douglas Fir ◽  
Conifer Forest ◽  
Mixed Conifer ◽  
Silvicultural Treatments ◽  
Mixed Conifer Forest ◽  
Armillaria Root Disease

Abstract In 2005, the 10-year effects of two silvicultural treatments (group-selection and shelterwood) on tree-growth loss and mortality caused by Armillaria ostoyae were compared with no treatment in a mixed-conifer forest in south-central Oregon. Ten years after treatment, Armillaria-caused mortality varied by species and was greatest in Shasta red fir (38% of trees per acre) and white fir (31%) and much less in Douglas-fir (3%) and ponderosa pine (0%). Ten years after harvesting, leave-tree mortality caused by Armillaria root disease was not significantly different in treated than in the unharvested units, nor was there significant diameter-growth response to the harvesting even in large ponderosa pine and Douglas-fir. The silvicultural treatments did have some benefits: (1) leave-tree mortality appeared, at least, not to be exacerbated by harvesting; (2) more disease-resistant pine, cedar, and larch seedlings and saplings survived in the shelterwood-harvest stands and group-selection openings than in comparable areas that were not harvested; and (3) living wood fiber was recovered from the treated stands, as well as dying and dead fuels that could exacerbate wildfire losses. Insights into host-pathogen interactions and recommendations for silvicultural options are presented. This is a case study from a single site and should be interpreted as such.

Using light to predict fuels-reduction and group-selection effects on succession in Sierran mixed-conifer forest

2011 ◽  
Vol 41 (10) ◽  
pp. 2051-2063 ◽  
Author(s):  
Seth W. Bigelow ◽  
Malcolm P. North ◽  
Carl F. Salk
Keyword(s):  
Sierra Nevada ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Group Selection ◽  
Wildlife Habitat ◽  
Conifer Forest ◽  
Mixed Conifer ◽  
Fuels Reduction ◽  
Mixed Conifer Forest ◽  
Large Trees

Many semi-arid coniferous forests in western North America have reached historically unprecedented densities over the past 150 years and are dominated by shade-tolerant trees. Silvicultural treatments generally open the canopy but may not restore shade-intolerant species. We determined crossover-point irradiance (CPI) (light at which the height growth rank of pairs of species changes) for seedlings in Sierra Nevada mixed-conifer forest and used these to interpret light environments produced by fuels-reduction thinning and group selection with reserved large trees. Nine of 21 species pairs had well-defined CPIs. The CPI of the most common shade-tolerant and intolerant species (white fir ( Abies concolor (Gordon & Glendl.) Lindl. ex Hildebr.) and ponderosa pine ( Pinus ponderosa Douglas ex P. Lawson & C. Lawson)) was 22.5 mol·m–2·day–1 or 41% of full sun. Median understory irradiance increased from 9.2 mol·m–2·day–1 (17% full sun) in pretreatment forest to 13 mol·m–2·day–1 (24% full sun) in lightly and 15.5 mol·m–2·day–1 (28% full sun) in moderately thinned stands and 37 mol·m–2·day–1 (67% full sun) in group-selection openings. We estimate that 5%–20% of ground area in lightly to moderately thinned stands would have enough light to favor shade-intolerant over shade-tolerant growth compared with 89% of ground area in group-selection openings. The CPI provides a tool to assess regeneration implications of treatment modification such as increasing heterogeneity of thinning to enhance regeneration or reserving large trees in group-selection openings to maintain wildlife habitat.

scholarly journals Cross-scale interaction of host tree size and climatic water deficit governs bark beetle-induced tree mortality

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Michael J. Koontz ◽  
Andrew M. Latimer ◽  
Leif A. Mortenson ◽  
Christopher J. Fettig ◽  
Malcolm P. North
Keyword(s):  
Water Deficit ◽  
Sierra Nevada ◽  
Bark Beetle ◽  
Ponderosa Pine ◽  
Tree Mortality ◽  
Mortality Rates ◽  
Dendroctonus Brevicomis ◽  
Scale Interactions ◽  
Climatic Water Deficit ◽  
Host Mortality

AbstractThe recent Californian hot drought (2012–2016) precipitated unprecedented ponderosa pine (Pinus ponderosa) mortality, largely attributable to the western pine beetle (Dendroctonus brevicomis; WPB). Broad-scale climate conditions can directly shape tree mortality patterns, but mortality rates respond non-linearly to climate when local-scale forest characteristics influence the behavior of tree-killing bark beetles (e.g., WPB). To test for these cross-scale interactions, we conduct aerial drone surveys at 32 sites along a gradient of climatic water deficit (CWD) spanning 350 km of latitude and 1000 m of elevation in WPB-impacted Sierra Nevada forests. We map, measure, and classify over 450,000 trees within 9 km2, validating measurements with coincident field plots. We find greater size, proportion, and density of ponderosa pine (the WPB host) increase host mortality rates, as does greater CWD. Critically, we find a CWD/host size interaction such that larger trees amplify host mortality rates in hot/dry sites. Management strategies for climate change adaptation should consider how bark beetle disturbances can depend on cross-scale interactions, which challenge our ability to predict and understand patterns of tree mortality.

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