scholarly journals Sierra Nevada fire severity conclusions are robust to further analysis: a reply to Safford et al.

2015 ◽  
Vol 24 (2) ◽  
pp. 294 ◽  
Author(s):  
Chad T. Hanson ◽  
Dennis C. Odion
Keyword(s):  
Sierra Nevada ◽  
Wildland Fire ◽  
Fire Severity ◽  
Forest Service ◽  
Conifer Forests ◽  
Forest Types ◽  
Increasing Trend ◽  
Us Forest Service

Safford et al. (this issue) question our earlier findings that fire severity has not increased in Sierra Nevada conifer forests 1984–2010, hypothesising that an increasing trend might have appeared had we restricted our analysis to wildland fire in frequent-fire forest types on US Forest Service lands. Here, we tested that hypothesis and again found no trend of increasing severity.

scholarly journals Black-Backed Woodpecker Nest Density in the Sierra Nevada, California

Diversity ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 364
Author(s):  
Chad T. Hanson ◽  
Tonja Y. Chi
Keyword(s):  
Sierra Nevada ◽  
Bark Beetles ◽  
Wildland Fire ◽  
Fire Suppression ◽  
Small Population ◽  
Nest Density ◽  
Conifer Forests ◽  
Forest Habitat ◽  
High Severity ◽  
Selection Of

In the western U.S., the black-backed woodpecker has been found to be associated with dense montane conifer forests with high snag densities, typically resulting from moderate- to high-severity wildland fires. However, black-backed woodpeckers are occasionally also detected nesting in unburned forests, raising questions about the type of habitat in which they nest and the potential abundance of such habitat. We conducted intensive black-backed woodpecker nest density surveys in large plots within the middle/upper-montane conifer forests of the Sierra Nevada, California, within general (undisturbed) forests, snag forest habitat from moderate/high-severity wildland fire, and unburned snag forest habitat from drought and native bark beetles. We found black-backed woodpeckers nesting only in the two snag forest conditions, mostly in burned snag forest, and their preferential selection of burned snag forest was statistically significant. No nest was found in general forests. Our spatial analysis indicates that snag forest is rare in the forests of the Sierra Nevada due to fire suppression and logging, raising concerns regarding small population size, which we estimate to be only 461 to 772 pairs in the Sierra Nevada.

Fire Severity in Conifer Forests of the Sierra Nevada, California

Ecosystems ◽  
2006 ◽  
Vol 9 (7) ◽  
pp. 1177-1189 ◽  
Author(s):  
Dennis C. Odion ◽  
Chad T. Hanson
Keyword(s):  
Sierra Nevada ◽  
Fire Severity ◽  
Conifer Forests

A multi-century history of fire regimes along a transect of mixed-conifer forests in central Oregon, U.S.A.

2019 ◽  
Vol 49 (1) ◽  
pp. 76-86 ◽  
Author(s):  
Emily K. Heyerdahl ◽  
Rachel A. Loehman ◽  
Donald A. Falk
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Fire Severity ◽  
Fire Regimes ◽  
Conifer Forests ◽  
Forest Types ◽  
Mixed Conifer ◽  
High Severity ◽  
Mixed Conifer Forests ◽  
History Of

Dry mixed-conifer forests are widespread in the interior Pacific Northwest, but their historical fire regimes are poorly characterized, in particular the relative mix of low- and high-severity fire. We reconstructed a multi-century history of fire from tree rings in dry mixed-conifer forests in central Oregon. These forests are dominated by ponderosa pine (Pinus ponderosa Lawson & C. Lawson), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and grand fir (Abies grandis (Douglas ex D. Don) Lindl.). Across four, 30-plot grids of ∼800 ha covering a mosaic of dry mixed-conifer forest types, we sampled 4065 trees for evidence of both high- and low-severity fire. From 1650 to ∼1900, all four sites sustained frequent, often extensive, low-severity fires that sometimes included small patches of severe fire (50–150 ha during 18%–28% of fire years). Fire intervals were similar among sites and also among forest types within sites (mean intervals of 14–32 years). To characterize the continuous nature of the variation in fire severity, we computed a plot-based index that captures the relative occurrence of low- and high-severity fire. Our work contributes to the growing understanding of variation in past fire regimes in the complex and dynamic forests of North America’s Interior West.

scholarly journals Differences in land ownership, fire management objectives and source data matter: a reply to Hanson and Odion (2014)

2015 ◽  
Vol 24 (2) ◽  
pp. 286 ◽  
Author(s):  
Hugh D. Safford ◽  
Jay D. Miller ◽  
Brandon M. Collins
Keyword(s):  
Sierra Nevada ◽  
Fire Management ◽  
Fire Severity ◽  
Fire Regimes ◽  
Forest Types ◽  
Coarse Scale ◽  
Vegetation Map ◽  
Management Objectives ◽  
Source Data ◽  
In Fire

We respond to Hanson and Odion (2014), who claim in this journal (vol. 23, no. 1, pp. 1–8) that their reanalysis of fire severity patterns in and around the Sierra Nevada refutes earlier work showing increases in fire severity in certain forest types over the last 3 decades. Hanson and Odion base their reanalysis on a highly inaccurate, very coarse-scale, and geographically misregistered vegetation map. Also, in contrast to the previous work, which was restricted to wildfires on Forest Service lands in forest types differentiated by their fire regimes, Hanson and Odion combine all types of fires on lands of all jurisdictions and stratify by very broad, unorthodox vegetation types that conjoin very different fire regimes. As such, their work does not constitute a test of the previous work. We present analyses that demonstrate sources of error associated with Hanson and Odion’s data and the analyses they perform, and explore how that error might confound their results. Fundamental and compounded problems in Hanson and Odion (2014) cast strong doubt on their conclusions.

scholarly journals Fire and Mechanical Forest Management Treatments Support Different Portions of the Bird Community in Fire-Suppressed Forests

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 150
Author(s):  
Lance Jay Roberts ◽  
Ryan Burnett ◽  
Alissa Fogg
Keyword(s):  
Sierra Nevada ◽  
Fire Severity ◽  
Bird Species ◽  
Bird Community ◽  
Fire Disturbance ◽  
Long Term Effects ◽  
High Severity ◽  
Commercial Thinning ◽  
Silvicultural Management ◽  
Total Community

Silvicultural treatments, fire, and insect outbreaks are the primary disturbance events currently affecting forests in the Sierra Nevada Mountains of California, a region where plants and wildlife are highly adapted to a frequent-fire disturbance regime that has been suppressed for decades. Although the effects of both fire and silviculture on wildlife have been studied by many, there are few studies that directly compare their long-term effects on wildlife communities. We conducted avian point counts from 2010 to 2019 at 1987 in situ field survey locations across eight national forests and collected fire and silvicultural treatment data from 1987 to 2016, resulting in a 20-year post-disturbance chronosequence. We evaluated two categories of fire severity in comparison to silvicultural management (largely pre-commercial and commercial thinning treatments) as well as undisturbed locations to model their influences on abundances of 71 breeding bird species. More species (48% of the community) reached peak abundance at moderate-high-severity-fire locations than at low-severity fire (8%), silvicultural management (16%), or undisturbed (13%) locations. Total community abundance was highest in undisturbed dense forests as well as in the first few years after silvicultural management and lowest in the first few years after moderate-high-severity fire, then abundance in all types of disturbed habitats was similar by 10 years after disturbance. Even though the total community abundance was relatively low in moderate-high-severity-fire habitats, species diversity was the highest. Moderate-high-severity fire supported a unique portion of the avian community, while low-severity fire and silvicultural management were relatively similar. We conclude that a significant portion of the bird community in the Sierra Nevada region is dependent on moderate-high-severity fire and thus recommend that a prescribed and managed wildfire program that incorporates a variety of fire effects will best maintain biodiversity in this region.

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.

Stratified forest inventory estimation with mapped plots

2005 ◽  
Vol 35 (10) ◽  
pp. 2382-2386 ◽  
Author(s):  
Paul C Van Deusen
Keyword(s):  
Forest Inventory ◽  
Forest Service ◽  
Forest Types ◽  
Inventory Data ◽  
Expansion Factor ◽  
Usda Forest Service ◽  
Weighted Estimation ◽  
Forest Conditions

Weighted estimation formulas are developed for producing stratified estimates of means and variances where data come from plots that can contain multiple forest conditions. Each plot is mapped to allow the analyst to focus on specific forest types or conditions. The weights required to accommodate mapped plots are somewhat more complicated than the weights for unmapped plots. In particular, these weights depend on the mapped condition of interest. The implication is that a single plot weight or expansion factor will not suffice for all analyses as it does for unmapped plots. The methods are demonstrated using USDA Forest Service inventory data.

Characterizing the light environment in Sierra Nevada mixed-conifer forests using a spatially explicit light model

2004 ◽  
Vol 34 (6) ◽  
pp. 1332-1342 ◽  
Author(s):  
Rolf Gersonde ◽  
John J Battles ◽  
Kevin L O'Hara
Keyword(s):  
Leaf Area ◽  
Sierra Nevada ◽  
Forest Type ◽  
Individual Species ◽  
Spatially Explicit ◽  
Conifer Forests ◽  
Prediction Equations ◽  
Mixed Conifer ◽  
Sapwood Area ◽  
Mixed Conifer Forests

The spatially explicit light model tRAYci was calibrated to conditions in multi-aged Sierra Nevada mixed-conifer forests. To reflect conditions that are important to growth and regeneration of this forest type, we sampled a variety of managed mature stands with multiple canopy layers and cohorts. Calibration of the light model included determining leaf area density for individual species with the use of leaf area – sapwood area prediction equations. Prediction equations differed between species and could be improved using site index. The light model predicted point measurements from hemispherical photographs well over a range of 27%–63% light. Simplifying the crown representation in the tRAYci model to average values for species and canopy strata resulted in little reduction in model performance and makes the model more useful to applications with lower sampling intensity. Vertical light profiles in managed mixed-conifer stands could be divided into homogeneous, sigmiodal, and continuous gradients, depending on stand structure and foliage distribution. Concentration of leaf area in the upper canopy concentrates light resources on dominant trees in continuous canopies. Irregular canopies of multiaged stands, however, provide more light resources to mid-size trees and could support growth of shade-intolerant species. Knowledge of the vertical distribution of light intensity in connection with stand structural information can guide regulation of irregular stand structures to meet forest management objectives.

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