scholarly journals Effectiveness of Restoration Treatments for Reducing Fuels and Increasing Understory Diversity in Shrubby Mixed-Conifer Forests of the Southern Rocky Mountains, USA

Forests ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 508 ◽  
Author(s):  
Julie E. Korb ◽  
Michael T. Stoddard ◽  
David W. Huffman
Keyword(s):  
Prescribed Fire ◽  
Forest Restoration ◽  
Treatment Effectiveness ◽  
Conifer Forests ◽  
Mixed Conifer ◽  
Burn Treatment ◽  
Attack Tree ◽  
Natural Fire ◽  
Mixed Conifer Forests ◽  
And Control

Exclusion of natural surface fires in warm/dry mixed-conifer forests of the western U.S. has increased potential for stand-replacing crown fires and reduced resilience of these systems to other disturbances, such as drought and insect attack. Tree thinning and the application of prescribed fire are commonly used to restore more resilient ecological conditions, but currently, there is a lack of long-term data with which to evaluate restoration treatment effectiveness in forest types where resprouting shrubs dominate understory communities. At a mixed-conifer site in southwestern Colorado, we compared forest structure and understory vegetation responses to three restoration treatments (thin/burn, burn, and control) over 10 years in a completely randomized and replicated experiment. Forest density, canopy cover, and crown fuel loads were consistently lower, and crown base height was higher, in thin/burn than burn or controls, but the effects diminished over time. Ten years following treatment, >99% of all plant species within both treatments and the control were native in origin. There were no differences between treatments in understory richness, diversity, cover, or surface fuels, but graminoid cover more than doubled in all treatments over the 15-year monitoring period. Similarly, there was more than a 250% increase post-treatment in shrub density, with the greatest increases in the thin/burn treatment. In addition, we saw an increase in the average shrub height for both treatments and the control, with shrub stems >80 cm becoming the dominant size class in the thin/burn treatment. Conifer seedling density was significantly lower in thin/burn compared with burn and control treatments after 10 years. Taken together, these conditions create challenges for managers aiming to reestablish natural fire patterns and sustain mixed-conifer forests. To limit the dominance of resprouting shrubs and facilitate conifer regeneration after overstory thinning and prescribed fire, managers may need to consider new or more intensive approaches to forest restoration, particularly given current and projected climate change.

Fuel treatment effectiveness in California yellow pine and mixed conifer forests

2012 ◽  
Vol 274 ◽  
pp. 17-28 ◽  
Author(s):  
H.D. Safford ◽  
J.T. Stevens ◽  
K. Merriam ◽  
M.D. Meyer ◽  
A.M. Latimer
Keyword(s):  
Treatment Effectiveness ◽  
Conifer Forests ◽  
Mixed Conifer ◽  
Fuel Treatment ◽  
Mixed Conifer Forests ◽  
Yellow Pine

scholarly journals A comprehensive guide to fuel management practices for dry mixed conifer forests in the northwestern United States: Prescribed fire

2014 ◽  
Author(s):  
Theresa B. Jain ◽  
Mike A. Battaglia ◽  
Han-Sup Han ◽  
Russell T. Graham ◽  
Christopher R. Keyes ◽  
...  
Keyword(s):  
United States ◽  
Prescribed Fire ◽  
Management Practices ◽  
Conifer Forests ◽  
Fuel Management ◽  
Mixed Conifer ◽  
Mixed Conifer Forests

Pyrosilviculture: Combining prescribed fire with gap-based silviculture in mixed-conifer forests of the Sierra Nevada

2020 ◽  
Author(s):  
Robert A. York ◽  
Hunter Noble ◽  
Lenya Quinn-Davidson ◽  
John J. Battles
Keyword(s):  
Sierra Nevada ◽  
Prescribed Fire ◽  
Fire Hazard ◽  
Stand Age ◽  
Conifer Forests ◽  
Mixed Conifer ◽  
Commercial Thinning ◽  
Crown Scorch ◽  
Mixed Conifer Forests ◽  
Giant Sequoia

We used a prescribed fire study to demonstrate the concept of pyrosilviculture, defined here as a) using prescribed fire to meet management objectives or b) altering non-fire silvicultural treatments explicitly so that they can optimize the incorporation of prescribed fire in the future. The study included implementation of relatively hot prescribed burns in mixed-conifer forests that have been managed with gap-based silviculture. The fires burned through 12-, 22-, 32- and, 100-year old cohorts, thus enabling an analysis of stand age influences on fire effects. Mastication and pre-commercial thinning were assessed as pre-fire treatments in the 12-year-old stands. Post-burn mortality and crown scorch declined with stand age. There was a clear tradeoff between fuel consumption and high rates of tree damage and mortality in the 12-year-old stands. Masticated stands had higher levels of average crown scorch (78%) compared with pre-commercially thinned stands (52%). Mortality for all 12-year-old stands was high, as nearly half of the trees were dead one year after the fires. Giant sequoia and ponderosa pine had relatively high resistance to prescribed fire-related mortality. When applying the concept of pyrosilviculture, there could be opportunities to combine prescribed fire with regeneration harvests that create a variety of gap sizes in order to sustain both low fire hazard and to promote structural heterogeneity and sustainable age structures that may not be achieved with prescribed fires alone.

scholarly journals Drivers of understory plant communities in Sierra Nevada mixed conifer forests with pyrodiversity

Fire Ecology ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Kate Wilkin ◽  
Lauren Ponisio ◽  
Danny L. Fry ◽  
Brandon M. Collins ◽  
Tadashi Moody ◽  
...  
Keyword(s):  
Sierra Nevada ◽  
Plant Communities ◽  
Canopy Cover ◽  
Conifer Forests ◽  
Mixed Conifer ◽  
Natural Fire ◽  
Mixed Conifer Forests ◽  
Tree Canopy Cover ◽  
Understory Plant ◽  
Understory Plant Communities

Abstract Background Fire suppression in western North America increased and homogenized overstory cover in conifer forests, which likely affected understory plant communities. We sought to characterize understory plant communities and their drivers using plot-based observations from two contemporary reference sites in the Sierra Nevada, USA. These sites had long-established natural fire programs, which have resulted in restored natural fire regimes. In this study, we investigated how pyrodiversity—the diversity of fire size, severity, season, and frequency—and other environment factors influenced species composition and cover of forest understory plant communities. Results Understory plant communities were influenced by a combination of environmental, plot-scale recent fire history, and plot-neighborhood pyrodiversity within 50 m. Canopy cover was inversely proportional to understory plant cover, Simpson’s diversity, and evenness. Species richness was strongly influenced by the interaction of plot-based fire experience and plot-neighborhood pyrodiversity within 50 m. Conclusions Pyrodiversity appears to contribute both directly and indirectly to diverse understory plant communities in Sierra Nevada mixed conifer forests. The indirect influence is mediated through variability in tree canopy cover, which is partially related to variation in fire severity, while direct influence is an interaction between local and neighborhood fire activity.

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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