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

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.

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Thermal alteration of soil physico-chemical properties: a systematic study to infer response of Sierra Nevada climosequence soils to forest fires

SOIL ◽

10.5194/soil-2-351-2016 ◽

2016 ◽

Vol 2 (3) ◽

pp. 351-366 ◽

Cited By ~ 14

Author(s):

Samuel N. Araya ◽

Mercer Meding ◽

Asmeret Asefaw Berhe

Keyword(s):

Climate Change ◽

Sierra Nevada ◽

Heating Temperature ◽

Chemical Properties ◽

Fire Intensity ◽

Western Slope ◽

Climate Change Scenarios ◽

Thermal Alteration ◽

Physico Chemical ◽

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 thermal alteration of soils' physical and chemical properties after they are exposed to a range of temperatures that are expected during prescribed and wildland fires. For this study, we used topsoils collected from 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 had significant differences in soil organic matter (SOM) concentration and mineralogy owing to the effects of climate on soil development. 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 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 increasing 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 temperature. Most of the statistically significant changes (p  <  0.05) occurred between 350 and 450 °C. We observed relatively smaller changes at temperature ranges below 250 °C. This study identifies critical temperature thresholds for significant physico-chemical changes in soils that developed under different climate regimes. Our findings will be of interest to studies of inferences for how soils are likely to respond to different fire intensities under anticipated climate change scenarios.

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Climate change impacts on forest growth and tree mortality: a data-driven modeling study in the mixed-conifer forest of the Sierra Nevada, California

Climatic Change ◽

10.1007/s10584-007-9358-9 ◽

2007 ◽

Vol 87 (S1) ◽

pp. 193-213 ◽

Cited By ~ 43

Author(s):

John J. Battles ◽

Timothy Robards ◽

Adrian Das ◽

Kristen Waring ◽

J. Keith Gilless ◽

...

Keyword(s):

Climate Change ◽

Sierra Nevada ◽

Tree Mortality ◽

Climate Change Impacts ◽

Forest Growth ◽

Data Driven ◽

Conifer Forest ◽

Mixed Conifer ◽

Mixed Conifer Forest ◽

Data Driven Modeling

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Tree mortality patterns following prescribed fires in a mixed conifer forest

Canadian Journal of Forest Research ◽

10.1139/x06-183 ◽

2006 ◽

Vol 36 (12) ◽

pp. 3222-3238 ◽

Cited By ~ 54

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.

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