The influence of pre-fire growth patterns on post-fire tree mortality for common conifers in western US parks

2020 ◽  
Vol 29 (6) ◽  
pp. 513 ◽  
Author(s):  
Phillip J. van Mantgem ◽  
Donald A. Falk ◽  
Emma C. Williams ◽  
Adrian J. Das ◽  
Nathan L. Stephenson
Keyword(s):  
National Parks ◽  
Tree Mortality ◽  
Fire Severity ◽  
Moisture Stress ◽  
Growth Patterns ◽  
Fire Intensity ◽  
Fire Growth ◽  
Average Growth ◽  
Crown Scorch ◽  
Western Us

Fire severity in forests is often defined in terms of post-fire tree mortality, yet the influences on tree mortality following fire are not fully understood. Pre-fire growth may serve as an index of vigour, indicating resource availability and the capacity to recover from injury and defend against pests. For trees that are not killed immediately by severe fire injury, tree growth patterns could therefore partially predict post-fire mortality probabilities. Here, we consider the influence of multiple growth patterns on post-fire tree mortality for three common conifer species in the western USA. Using observations from 1 to 9 years following prescribed fires in USA national parks across five western states, we show that post-fire conifer mortality was related not only to fire-caused injuries (crown scorch and bole char), but also to average growth rate and long-term (25 years) growth patterns (counts of abrupt growth declines and possibly growth trends). Our results suggest that pre-fire conditions affecting tree vigour may influence post-fire tree mortality probabilities. Environmental conditions (such as rising temperatures and moisture stress), independent of fire intensity, may thus cause expressed fire severity to increase in western forests.

Fuel treatments alter the effects of wildfire in a mixed-evergreen forest, Oregon, USA

2005 ◽  
Vol 35 (12) ◽  
pp. 2981-2995 ◽  
Author(s):  
Crystal L Raymond ◽  
David L Peterson
Keyword(s):  
Tree Mortality ◽  
Fire Regime ◽  
Fire Severity ◽  
Fire Behavior ◽  
Evergreen Forest ◽  
Fire Intensity ◽  
Crown Fire ◽  
Fuel Loading ◽  
Fuel Treatments ◽  
Surface Fire

We had the rare opportunity to quantify the relationship between fuels and fire severity using prefire surface and canopy fuel data and fire severity data after a wildfire. The study area is a mixed-evergreen forest of southwestern Oregon with a mixed-severity fire regime. Modeled fire behavior showed that thinning reduced canopy fuels, thereby decreasing the potential for crown fire spread. The potential for crown fire initiation remained fairly constant despite reductions in ladder fuels, because thinning increased surface fuels, which contributed to greater surface fire intensity. Thinning followed by underburning reduced canopy, ladder, and surface fuels, thereby decreasing surface fire intensity and crown fire potential. However, crown fire is not a prerequisite for high fire severity; damage to and mortality of overstory trees in the wildfire were extensive despite the absence of crown fire. Mortality was most severe in thinned treatments (80%–100%), moderate in untreated stands (53%–54%), and least severe in the thinned and underburned treatment (5%). Thinned treatments had higher fine-fuel loading and more extensive crown scorch, suggesting that greater consumption of fine fuels contributed to higher tree mortality. Fuel treatments intended to minimize tree mortality will be most effective if both ladder and surface fuels are treated.

scholarly journals Long-term changes in masticated woody fuelbeds in northern California and southern Oregon, USA

2020 ◽  
Vol 29 (9) ◽  
pp. 807
Author(s):  
Warren P. Reed ◽  
J. Morgan Varner ◽  
Eric E. Knapp ◽  
Jesse K. Kreye
Keyword(s):  
Tree Mortality ◽  
Fire Hazard ◽  
Fire Intensity ◽  
Fuel Loading ◽  
Fire Hazards ◽  
Fuels Treatment ◽  
Fuel Layer ◽  
Long Duration ◽  
Western Us ◽  
Residual Tree

Mechanical mastication is a fuels treatment that shreds midstorey trees and shrubs into a compacted woody fuel layer to abate fire hazards in fire-prone ecosystems. Increased surface fuel loading from mastication may, however, lead to undesirable fire intensity, long-duration flaming or smouldering, and undesirable residual tree mortality. Two major questions facing fuels managers are: how long do masticated fuels persist, and how does the composition of masticated fuelbeds change over time? To evaluate these changes, we measured 25 masticated sites with a range of vegetation, species masticated and time since treatment (1–16 years) in the western US. Seven of the 25 sites were sampled nearly a decade earlier, providing a unique opportunity to document fuelbed changes. Woody fuel loading ranged from 12.1 to 91.9Mg ha−1 across sites and was negatively related to time since treatment. At remeasured sites, woody fuel loads declined by 20%, with the greatest losses in 1- and 10-h woody fuels (69 and 33% reductions in mass respectively). Reductions were due to declines in number of particles and reduced specific gravity. Mastication treatments that generate greater proportions of smaller-diameter fuels may result in faster decomposition and potentially be more effective at mitigating fire hazard.

Post-fire survival and flushing in three Sierra Nevada conifers with high initial crown scorch

2009 ◽  
Vol 18 (7) ◽  
pp. 857 ◽  
Author(s):  
Chad T. Hanson ◽  
Malcolm P. North
Keyword(s):  
Sierra Nevada ◽  
Pinus Ponderosa ◽  
Fire Severity ◽  
Conifer Species ◽  
Mature Trees ◽  
Salvage Logging ◽  
Abies Magnifica ◽  
Crown Scorch ◽  
Tree Survival ◽  
Large Trees

With growing debate over the impacts of post-fire salvage logging in conifer forests of the western USA, managers need accurate assessments of tree survival when significant proportions of the crown have been scorched. The accuracy of fire severity measurements will be affected if trees that initially appear to be fire-killed prove to be viable after longer observation. Our goal was to quantify the extent to which three common Sierra Nevada conifer species may ‘flush’ (produce new foliage in the year following a fire from scorched portions of the crown) and survive after fire, and to identify tree or burn characteristics associated with survival. We found that, among ponderosa pines (Pinus ponderosa Dougl. ex. Laws) and Jeffrey pines (Pinus jeffreyi Grev. & Balf) with 100% initial crown scorch (no green foliage following the fire), the majority of mature trees flushed, and survived. Red fir (Abies magnifica A. Murr.) with high crown scorch (mean = 90%) also flushed, and most large trees survived. Our results indicate that, if flushing is not taken into account, fire severity assessments will tend to overestimate mortality and post-fire salvage could remove many large trees that appear dead but are not.

Fire regime impacts on post-fire diurnal land surface temperature change over North American boreal forest

2021 ◽  
Author(s):  
Jie Zhao ◽  
Chao Yue ◽  
Philippe Ciais ◽  
Xin Hou ◽  
Qi Tian
Keyword(s):  
Climate Change ◽  
Regression Analysis ◽  
Land Surface ◽  
Fire Regime ◽  
Fire Severity ◽  
Linear Regression Analysis ◽  
Fire Regimes ◽  
Fire Intensity ◽  
Surface Temperature Change ◽  
One Year

<p>Wildfire is the most prevalent natural disturbance in the North American boreal (BNA) forest and can cause post-fire land surface temperature change (ΔLST<sub>fire</sub>) through biophysical processes. Fire regimes, such as fire severity, fire intensity and percentage of burned area (PBA), might affect ΔLST<sub>fire</sub> through their impacts on post-fire vegetation damage. However, the difference of the influence of different fire regimes on the ΔLST<sub>fire</sub> has not been quantified in previous studies, despite ongoing and projected changes in fire regimes in BNA in association with climate change. Here we employed satellite observations and a space-and-time approach to investigate diurnal ΔLST<sub>fire</sub> one year after fire across BNA. We further examined potential impacts of three fire regimes (i.e., fire intensity, fire severity and PBA) and latitude on ΔLST<sub>fire</sub> by simple linear regression analysis and multiple linear regression analysis in a stepwise manner. Our results demonstrated pronounced asymmetry in diurnal ΔLST<sub>fire</sub>, characterized by daytime warming in contrast to nighttime cooling over most BNA. Such diurnal ΔLST<sub>fire</sub> also exhibits a clear latitudinal pattern, with stronger daytime warming and nighttime cooling one year after fire in lower latitudes, whereas in high latitudes fire effects are almost neutral. Among the fire regimes, fire severity accounted for the most (43.65%) of the variation of daytime ΔLST<sub>fire</sub>, followed by PBA (11.6%) and fire intensity (8.5%). The latitude is an important factor affecting the influence of fire regimes on daytime ΔLST<sub>fire</sub>. The sensitivity of fire intensity and PBA impact on daytime ΔLST<sub>fire</sub> decreases with latitude. But only fire severity had a significant effect on nighttime ΔLST<sub>fire</sub> among three fire regimes. Our results highlight important fire regime impacts on daytime ΔLST<sub>fire</sub>, which might play a critical role in catalyzing future boreal climate change through positive feedbacks between fire regime and post-fire surface warming.</p>

scholarly journals Interactive effects of ambient ozone and climate measured on growth of mature loblolly pine trees

1996 ◽  
Vol 26 (4) ◽  
pp. 670-681 ◽  
Author(s):  
S.B. McLaughlin ◽  
D.J. Downing
Keyword(s):  
Soil Moisture ◽  
Loblolly Pine ◽  
Moisture Stress ◽  
Growth Patterns ◽  
Forest Growth ◽  
Interactive Effects ◽  
Forest Trees ◽  
Short Term ◽  
Data Set ◽  
Ambient Ozone

Seasonal growth patterns of mature loblolly pine (Pinustaeda L.) trees over the interval 1988–1993 have been analyzed to evaluate the effects of ambient ozone on growth of large forest trees. Patterns of stem expansion and contraction of 34 trees were examined using serial measurements with sensitive dendrometer band systems. Study sites, located in eastern Tennessee, varied significantly in soil moisture, soil fertility, and stand density. Levels of ozone, rainfall, and temperature varied widely over the 6-year study interval. Regression analysis identified statistically significant influences of ozone on stem growth patterns, with responses differing widely among trees and across years. Ozone interacted with both soil moisture stress and high temperatures, explaining 63% of the high frequency, climatic variance in stem expansion identified by stepwise regression of the 5-year data set. Observed responses to ozone were rapid, typically occurring within 1–3 days of exposure to ozone at ≥40 ppb and were significantly amplified by low soil moisture and high air temperatures. Both short-term responses, apparently tied to ozone-induced increases in whole-tree water stress, and longer term cumulative responses were identified. These data indicate that relatively low levels of ambient ozone can significantly reduce growth of mature forest trees and that interactions between ambient ozone and climate are likely to be important modifiers of future forest growth and function. Additional studies of mechanisms of short-term response and interspecies comparisons are clearly needed.

scholarly journals A synthesis of radial growth patterns preceding tree mortality

2016 ◽  
Vol 23 (4) ◽  
pp. 1675-1690 ◽  
Author(s):  
Maxime Cailleret ◽  
Steven Jansen ◽  
Elisabeth M. R. Robert ◽  
Lucía Desoto ◽  
Tuomas Aakala ◽  
...  
Keyword(s):  
Radial Growth ◽  
Tree Mortality ◽  
Growth Patterns

scholarly journals Fire intensity impacts on post-fire temperate coniferous forest net primary productivity

2018 ◽  
Vol 15 (4) ◽  
pp. 1173-1183 ◽  
Author(s):  
Aaron M. Sparks ◽  
Crystal A. Kolden ◽  
Alistair M. S. Smith ◽  
Luigi Boschetti ◽  
Daniel M. Johnson ◽  
...  
Keyword(s):  
Primary Productivity ◽  
Tree Mortality ◽  
Net Primary Productivity ◽  
Coniferous Forest ◽  
Radiative Energy ◽  
Fire Intensity ◽  
Wildland Fires ◽  
Resistant Species ◽  
Legacy Effect ◽  
C Cycle

Abstract. Fire is a dynamic ecological process in forests and impacts the carbon (C) cycle through direct combustion emissions, tree mortality, and by impairing the ability of surviving trees to sequester carbon. While studies on young trees have demonstrated that fire intensity is a determinant of post-fire net primary productivity, wildland fires on landscape to regional scales have largely been assumed to either cause tree mortality, or conversely, cause no physiological impact, ignoring the impacted but surviving trees. Our objective was to understand how fire intensity affects post-fire net primary productivity in conifer-dominated forested ecosystems on the spatial scale of large wildland fires. We examined the relationships between fire radiative power (FRP), its temporal integral (fire radiative energy – FRE), and net primary productivity (NPP) using 16 years of data from the MOderate Resolution Imaging Spectrometer (MODIS) for 15 large fires in western United States coniferous forests. The greatest NPP post-fire loss occurred 1 year post-fire and ranged from −67 to −312 g C m−2 yr−1 (−13 to −54 %) across all fires. Forests dominated by fire-resistant species (species that typically survive low-intensity fires) experienced the lowest relative NPP reductions compared to forests with less resistant species. Post-fire NPP in forests that were dominated by fire-susceptible species were not as sensitive to FRP or FRE, indicating that NPP in these forests may be reduced to similar levels regardless of fire intensity. Conversely, post-fire NPP in forests dominated by fire-resistant and mixed species decreased with increasing FRP or FRE. In some cases, this dose–response relationship persisted for more than a decade post-fire, highlighting a legacy effect of fire intensity on post-fire C dynamics in these forests.

Health, growth and development of pre-school children in Newcastle upon Tyne

1979 ◽  
Vol 11 (4) ◽  
pp. 411-424
Author(s):  
H. Mary Fellowes ◽  
Catherine A. Hytten ◽  
W.Z. Billewicz ◽  
A.M. Thomson
Keyword(s):  
Growth Rates ◽  
Seasonal Changes ◽  
Growth Patterns ◽  
Transient Effect ◽  
Normal Children ◽  
Average Growth ◽  
Respiratory Illnesses ◽  
Developmental Test ◽  
One Year ◽  
Newcastle Upon Tyne

SummaryOne hunderd and forty 'normal' children aged 0—5 years, selected from three large general medical practices to represent a wide socioeconomic range, were seen monthly for periods of at least one year. Average growth patterns, previously shown to be related to the energy value of diets, conformed to British standards. Height and weight were not significantly related to socioeconomic status, maternal 'efficiency', number of sibs nor place in family. About half the children aged 0.5 years or less changed growht 'channels', falling to 0.4% in children aged 2 years or more. Respiratory illnesses showed seasonal changes, but growth rates did not, and there was no evidence that illness of any kind or severity had more than a transient effect on growth rates. Developmental test scores were not found to be related to growth rates. Girls tended to have higher scores than boys. Children from non-manual families and those with sїbs at least 5 years older scored more highly in tests of language than those in other types of family.

Fire and stand history in two limber pine (Pinus flexilis) and Rocky Mountain bristlecone pine (Pinus aristata) stands in Colorado

2008 ◽  
Vol 17 (3) ◽  
pp. 339 ◽  
Author(s):  
Peter M. Brown ◽  
Anna W. Schoettle
Keyword(s):  
Tree Mortality ◽  
Fire Severity ◽  
Rocky Mountain ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Ice Age ◽  
Tree Recruitment ◽  
Fire Scar ◽  
Limber Pine ◽  
Bristlecone Pine

We developed fire-scar and tree-recruitment chronologies from two stands dominated by limber pine and Rocky Mountain bristlecone pine in central and northern Colorado. Population structures in both sites exhibit reverse-J patterns common in uneven-aged forests. Bristlecone pine trees were older than any other at the site or in the limber pine stand, with the oldest tree dating to 780 AD and several dating to the 1000s and 1100s. The oldest trees in the limber pine stand date to the 1400s, with a majority of recruitment after an apparent bark beetle outbreak in the early 1800s. Spatial patterning in the limber pine suggests that the oldest trees established from seed caches left by corvid birds. Fire scars present in the early part of each chronology document that surface fire regimes dominated during certain periods. Decreased fire frequency, increased tree recruitment, and changes in species composition from the 1600s to1800s in the bristlecone pine may be reflective of cooler and wetter conditions during the Little Ice Age. Results suggest that a recent (1978) severe fire in the bristlecone pine stand that caused complete tree mortality was outside the historical range of variability in fire severity for at least the past ~1000 years.

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