scholarly journals High‐severity wildfire leads to multi‐decadal impacts on soil biogeochemistry in mixed‐conifer forests

2020 ◽  
Vol 30 (4) ◽  
Author(s):  
Nicholas C. Dove ◽  
Hugh D. Safford ◽  
Gabrielle N. Bohlman ◽  
Becky L. Estes ◽  
Stephen C. Hart
2015 ◽  
Vol 341 ◽  
pp. 45-58 ◽  
Author(s):  
Hélène M. Marcoux ◽  
Lori D. Daniels ◽  
Sarah E. Gergel ◽  
Eric Da Silva ◽  
Ze’ev Gedalof ◽  
...  

2019 ◽  
Vol 49 (1) ◽  
pp. 76-86 ◽  
Author(s):  
Emily K. Heyerdahl ◽  
Rachel A. Loehman ◽  
Donald A. Falk

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.


2015 ◽  
Vol 24 (4) ◽  
pp. 470 ◽  
Author(s):  
Christopher J. Dunn ◽  
John D. Bailey

Fire-resilient landscapes require the recurrent use of fire, but successful use of fire in previously burned areas must account for temporal fuel dynamics. We analysed factors influencing temporal fuel dynamics across a 24-year spatial chronosequence of unmanipulated dry mixed conifer forests following high-severity fire. Duff and litter accumulated as bark sloughed from snags and leaves senesced from recovering vegetation, averaging 14.6 Mg ha–1 and 22.1 Mg ha–1 at our 24-year post-fire site, respectively. 1-h fuels increased linearly, averaging 1.1 Mg ha–1 at our 24-year post-fire site, with additions occurring from recovering vegetation. 10-h and 100-h fuels exhibited non-linear temporal trends, with maximum loadings occurring 14 years (3.9 Mg ha–1) and 18 years (10.5 Mg ha–1) post-fire, respectively. 1000-h fuel accumulation slowed after 20 years post-fire (reached 124.6 Mg ha–1), concurrently with ~90% snag fall and fragmentation. Maximum herbaceous fuel loading averaged 0.73 Mg ha–1 at our 5-year post-fire sites, but only averaged 0.02 Mg ha–1 at all sites thereafter. Live shrub biomass accumulation slowed after 21 years post-fire, averaging 14.3 Mg ha–1 at our 24-year post-fire site. Managers can use post-fire temporal fuel dynamics to help facilitate the restoration of fire regimes while mitigating undesirable fire effects.


2020 ◽  
Author(s):  
Justin P. Ziegler ◽  
Chad M. Hoffman ◽  
Brandon M. Collins ◽  
Eric E. Knapp ◽  
William (Ruddy) Mell

2004 ◽  
Vol 34 (6) ◽  
pp. 1332-1342 ◽  
Author(s):  
Rolf Gersonde ◽  
John J Battles ◽  
Kevin L O'Hara

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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