scholarly journals Biophysical Settings that Influenced Plantation Survival During the 2015 Wildfires in Northern Rocky Mountain Moist Mixed-Conifer Forests

2021 ◽  
Author(s):  
Theresa B Jain ◽  
Andrew S Nelson ◽  
Benjamin C Bright ◽  
John C Byrne ◽  
Andrew T Hudak
Keyword(s):  
Snow Water Equivalent ◽  
Fire Suppression ◽  
Fire Severity ◽  
Rocky Mountain ◽  
Conifer Forests ◽  
Mixed Conifer ◽  
White Pine ◽  
Mixed Conifer Forests ◽  
Western White Pine ◽  
Sapling Survival

Abstract Fire suppression and the loss of western white pine (WWP) have made northern Rocky Mountain moist mixed-conifer forests less disturbance resilient. Although managers are installing hundreds of plantations, most of these plantations have not experienced wildfire since establishment. In 2015, wildfires burned through one hundred WWP plantations in this region, providing an opportunity to evaluate the effects of wildfires on sapling survival. A Weibull distribution approach was used to characterize the variation of fire severity pixels, as indicated by the differenced normalized burn ratio. The distribution parameters provided a method to identify the biophysical setting and plantation characteristics influencing fire severity and sapling survival. Plantations located on lower slope positions were more resistant to wildfires than plantations located midslope or close to the ridges. Snow water equivalent was positively correlated with wildfire resistance and resilience. Results will help focus reforestation efforts and identify locations where future plantations can potentially survive wildfires. Study Implications This study examined wildfire effects on western white pine plantations, with the intention to inform managers where to locate plantations that will be more resistant to wildfires and determine which plantations may require postfire reforestation. Plantations were more resilient and resistant to wildfires when they occurred on lower slopes, even when steep, indicating these places may be better suited for future plantations. Plantations located on upper slopes and ridges are vulnerable to wildfire even when located on moist habitat types and will likely need reforestation.

scholarly journals Susceptibility of Conifers to Three Dwarf Mistletoes in the Klamath-Siskiyou Mountains

2011 ◽  
Vol 26 (1) ◽  
pp. 13-18 ◽  
Author(s):  
Robert Mathiasen
Keyword(s):  
Host Susceptibility ◽  
Mixed Conifer ◽  
White Pine ◽  
Dwarf Mistletoe ◽  
Susceptibility Data ◽  
Mixed Conifer Forests ◽  
Western White Pine ◽  
Siskiyou Mountains ◽  
Study Sites ◽  
Live Tree

Abstract Dwarf mistletoes (Arceuthobium spp., Viscaceae) are parasitic flowering plants that infect members of the Pinaceae family in the western United States. This article reports additional host susceptibility data for three dwarf mistletoes found in the Klamath-Siskiyou Mountains of southwestern Oregon and northwestern California. Three mixed conifer stands, each infested with either mountain hemlock dwarf mistletoe, western white pine dwarf mistletoe, or Wiens' dwarf mistletoe (nine stands total) were sampled to evaluate the susceptibility of conifers to these parasites. At each of the study sites, 10–20 temporary circular plots with a 6-m radius (0.012 ha) were established around large, severely infected trees. Within plots, species, dbh, and dwarf mistletoe rating (six-class system) were determined for each live tree. On the basis of the incidence of infection, conifers were assigned to host susceptibility classes. Western white pine and mountain hemlock were principal hosts of western white pine and mountain hemlock dwarf mistletoes, respectively. Brewer spruce and red fir were principal hosts of Wiens' dwarf mistletoe. Other conifers sampled were less susceptible to these mistletoes. This information can be used by forest managers to mitigate the damage associated with infestations of these dwarf mistletoes in mixed conifer forests of the Klamath-Siskiyou Mountains.

scholarly journals The species diversity × fire severity relationship is hump‐shaped in semiarid yellow pine and mixed conifer forests

Ecosphere ◽  
2019 ◽  
Vol 10 (10) ◽  
Author(s):  
Clark Richter ◽  
Marcel Rejmánek ◽  
Jesse E. D. Miller ◽  
Kevin R. Welch ◽  
JonahMaria Weeks ◽  
...  
Keyword(s):  
Species Diversity ◽  
Fire Severity ◽  
Conifer Forests ◽  
Mixed Conifer ◽  
Mixed Conifer Forests ◽  
Yellow Pine

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 Pyric tree spatial patterning interactions in historical and contemporary mixed conifer forests, California, USA

2020 ◽  
Author(s):  
Justin P. Ziegler ◽  
Chad M. Hoffman ◽  
Brandon M. Collins ◽  
Eric E. Knapp ◽  
William (Ruddy) Mell
Keyword(s):  
Spatial Patterning ◽  
Conifer Forests ◽  
Mixed Conifer ◽  
Mixed Conifer Forests

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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