scholarly journals Efficacy of Chemical and Biological Stump Treatments for the Control of Heterobasidion occidentale Infection of California Abies concolor

Pathogens ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1390
Author(s):  
Adrian L. Poloni ◽  
Matteo Garbelotto ◽  
Christopher A. Lee ◽  
Richard C. Cobb
Keyword(s):  
Laboratory Test ◽  
Experimental Evaluation ◽  
Positive Control ◽  
Abies Concolor ◽  
Mixed Conifer ◽  
White Fir ◽  
Mixed Conifer Forests ◽  
Phlebiopsis Gigantea ◽  
The World ◽  
Pathogen Colonization

We conducted an experimental evaluation of treatments to limit Heterobasidion occidentale infection of white fir (Abies concolor) stumps and wounds in California mixed conifer forests. We tested the efficacy of urea, borate, and a mixture of two locally collected Phlebiopsis gigantea strains in preventing pathogen colonization of fir stumps and separately, urea and borate as infection controls on experimental stem wounds. These were paired with a laboratory test on ~100 g wood blocks with and without a one-week delay between inoculation and treatment. Urea, borates, and Phlebiopsis treatments all significantly reduced the stump surface area that was colonized by H. occidentale at 84%, 91%, and 68%, respectively, relative to the controls. However, only the borate treatments significantly lowered the number of stumps that were infected by the pathogen. The laboratory study matched the patterns that were found in the stump experiment with a reduced area of colonization for urea, borates, or P. gigantea treatments relative to the controls; delaying the treatment did not affect efficacy. The field wound experiment did not result in any Heterobasidion colonization, even in positive control treatments, rendering the experiment uninformative. Our study suggests treatments that are known to limit Heterobasidion establishment on pine or spruce stumps elsewhere in the world may also be effective on true firs in California.

The effects of burn entry and burn severity on ponderosa pine and mixed conifer forests in Grand Canyon National Park

2015 ◽  
Vol 24 (4) ◽  
pp. 495 ◽  
Author(s):  
Anna M. Higgins ◽  
Kristen M. Waring ◽  
Andrea E. Thode
Keyword(s):  
Ponderosa Pine ◽  
National Park ◽  
Forest Type ◽  
Grand Canyon ◽  
Burn Severity ◽  
Conifer Forests ◽  
Mixed Conifer ◽  
Grand Canyon National Park ◽  
White Fir ◽  
Mixed Conifer Forests

Over a century of fire exclusion in frequent-fire ponderosa pine and dry mixed conifer forests has resulted in increased tree densities, heavy surface fuel accumulations and an increase in late successional, fire-intolerant trees. Grand Canyon National Park uses prescribed fires and wildfires to reduce fire hazard and restore ecosystem processes. Research is needed to determine post-fire vegetation response thus enabling future forest succession predictions. Our study focussed on the effects of burn entry and burn severity on species composition and regeneration in two forest types: ponderosa pine with white fir encroachment and dry mixed conifer. We found no difference in tree composition and structure in a single, low-severity burn compared with unburned areas in the white fir encroachment forest type. We found no white fir seedlings or saplings in a second-entry, low-severity burn in the white fir encroachment forest type. Second-entry burns were effective in reducing white fir densities in the white fir encroachment forest type. There was significant aspen regeneration following high-severity fire in the dry mixed conifer forest type. This research suggests that repeated entries and an increase in burn severity may be necessary for prescribed fire or wildfire to be effective in meeting management objectives.

Litter dynamics in two Sierran mixed conifer forests. II. Nutrient release in decomposing leaf litter

1988 ◽  
Vol 18 (9) ◽  
pp. 1136-1144 ◽  
Author(s):  
Thomas J. Stohlgren
Keyword(s):  
Leaf Litter ◽  
Sierra Nevada ◽  
Nutrient Release ◽  
Conifer Forests ◽  
Mixed Conifer ◽  
Acid Detergent Fiber ◽  
White Fir ◽  
Mixed Conifer Forests ◽  
Sugar Pine ◽  
Giant Sequoia

The factors influencing leaf litter decomposition and nutrient release patterns were investigated for 3.6 years in two mixed conifer forests in the southern Sierra Nevada of California. The giant sequoia–fir forest was dominated by giant sequoia (Sequoiadendrongiganteum (Lindl.) Buchh.), white fir (Abiesconcolor Lindl. & Gord.), and sugar pine (Pinuslambertiana Dougl.). The fir–pine forest was dominated by white fir, sugar pine, and incense cedar (Calocedrusdecurrens (Torr.) Florin). Initial concentrations of nutrients and percent lignin, cellulose, and acid detergent fiber vary considerably in freshly abscised leaf litter of the studied species. Giant sequoia had the highest concentration of lignin (20.3%) and the lowest concentration of nitrogen (0.52%), while incense cedar had the lowest concentration of lignin (9.6%) and second lowest concentration of nitrogen (0.63%). Long-term (3.6 years) foliage decomposition rates were best correlated with initial lignin/N (r2 = 0.94, p < 0.05), lignin concentration (r2 = 0.92, p < 0.05), and acid detergent fiber concentration (r2 = 0.80, p < 0.05). Patterns of nutrient release were highly variable. Giant sequoia immobilized N and P, incense cedar immobilized N and to a lesser extent P, while sugar pine immobilized Ca. Strong linear or negative exponential relationships existed between initial concentrations of N, P, K, and Ca and percent original mass remaining of those nutrients after 3.6 years. This suggests efficient retention of these nutrients in the litter layer of these ecosystems. Nitrogen concentrations steadily increase in decomposing leaf litter, effectively reducing the C/N ratios from an initial range of 68–96 to 27–45 after 3.6 years.

Post-fire epicormic branching in Sierra Nevada Abies concolor (white fir)

2006 ◽  
Vol 15 (1) ◽  
pp. 31 ◽  
Author(s):  
Chad T. Hanson ◽  
Malcolm P. North
Keyword(s):  
Sierra Nevada ◽  
Fire Suppression ◽  
Large Diameter ◽  
Abies Concolor ◽  
Conifer Forest ◽  
Mixed Conifer ◽  
Diameter Class ◽  
Mixed Conifer Forest ◽  
White Fir ◽  
Epicormic Branching

In California’s mixed-conifer forest, which historically had a regime of frequent fires, two conifers, Sequoiadendron giganteum and Pseudotsuga menziesii, were previously known to produce epicormic sprouts from branches. We found epicormic branching in a third mixed-conifer species, Abies concolor, 3 and 4 years after a wildfire in the central Sierra Nevada Mountains of California. Sprouting occurred only from the boles. We investigated (1) whether the degree of crown loss and the extent of epicormic branching were independent; and (2) whether epicormic branching differed by tree size. The vertical extent of epicormic foliage increased with increasing severity of crown loss. There was a significantly greater proportion of large diameter-class (>50 cm diameter at breast height [dbh]) trees with epicormic branching than small/medium diameter-class (25–50 cm dbh) trees. These results suggest large diameter Abies concolor may survive high levels of crown loss, aided by crown replacement through epicormic branching, but that reiterative green foliage may not appear for up to 3 years after fire damage. If this response is widespread, it would suggest some ‘dying’ trees logged under current salvage guidelines could survive, and that higher-intensity fire may substantially reduce the density of small post-fire suppression white fir, while retaining many larger overstory trees.

Short- and long-term growth characteristics associated with tree mortality in southwestern mixed-conifer forests

2014 ◽  
Vol 44 (10) ◽  
pp. 1227-1235 ◽  
Author(s):  
Jeffrey M. Kane ◽  
Thomas E. Kolb
Keyword(s):  
Tree Mortality ◽  
Douglas Fir ◽  
Growth Characteristics ◽  
Conifer Forests ◽  
Mixed Conifer ◽  
Dead Trees ◽  
White Fir ◽  
Mixed Conifer Forests ◽  
Short And Long Term

Continued increases in global temperatures and incidences of drought have been implicated in elevated tree mortality in many regions, prompting interest in better understanding tree mortality processes. A recent extreme drought in the southwestern U.S. (1996–2003) contributed to elevated tree mortality throughout the region. We used this event to investigate the relationship of short- and long-term tree growth characteristics to recent (1996–2008) tree mortality in the mixed-conifer forests in northern Arizona. We compared radial growth characteristics over a 50-year period between paired live and recently dead white fir (Abies concolor (Gordon & Glend.) Lindl. ex Hildebr.), limber pine (Pinus flexilis E. James), trembling aspen (Populus tremuloides Michx.), and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). We found that (i) dead trees of all species typically had lower mean growth rates than live trees, (ii) dead trees of most species had a greater coefficient of variation in growth over long time periods (>20 years) than live trees, (iii) dead aspen and dead Douglas-fir trees had larger negative growth trends than live trees for some time periods, (iv) dead trees of most species had larger numbers of abrupt growth declines than live trees, and (v) a combination of short- and long-term growth characteristics distinguished live and dead trees, with greater importance of short-term growth for aspen, long-term growth for limber pine, and a mix of short- and long-term growth for white fir and Douglas-fir. These results strongly suggest that recent tree mortality in southwestern mixed-conifer forests is caused by a mixture of short- and long-term processes.

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

Pathogens and insects in a pristine forest ecosystem: the Sierra San Pedro Martir, Baja, Mexico

2002 ◽  
Vol 32 (3) ◽  
pp. 448-457 ◽  
Author(s):  
Patricia E Maloney ◽  
David M Rizzo
Keyword(s):  
Forest Ecosystem ◽  
Bark Beetles ◽  
Stand Structure ◽  
Linear Regression Analysis ◽  
Mixed Conifer ◽  
San Pedro ◽  
White Fir ◽  
Sugar Pine ◽  
Sierra San Pedro Martir ◽  
Pristine Forest

We determined the incidence of pathogens and insects across mixed-conifer stands in the Sierra San Pedro Martir (SSPM) of northern Baja, Mexico, to assess the role of pests in a pristine forest ecosystem. We also determined the spatial distribution of the two most common pests, mistletoe, Phoradendron pauciflorum Torrey, and the fir engraver, Scolytus ventralis LeConte, of white fir (Abies concolor (Gord. & Glend.) Lindl.) across a 25-ha grid to assess spread and what host and pest variables were related. In these open parklike stands the mean tree density was 160 trees/ha, of which 58% were trees >20 cm diameter at breast height (DBH). In these low-density, mixed-aged stands we found that mixed-conifer species were well represented with no one species being completely dominant. Percent cumulative mortality for the SSPM was 12.7%, ranging from 2 to 24%, with the greatest amount of mortality occurring in the larger size classes, trees [Formula: see text]50 cm DBH. Multiple linear regression analysis showed that 78% of the mortality we observed was explained by pathogens and bark beetles (r2 = 0.78, P = 0.0001, F = 84). Mean pest incidence for Jeffrey pine (Pinus jeffreyi Grev. & Balf. in A. Murray), white fir, and sugar pine (Pinus lambertiana Dougl.) was 21, 88, and 2%, respectively. We found a number of relationships among host and pest variables, as well as a pathogen– insect interaction, and across the SSPM we found that nonhost species may be interfering in certain host–pest interactions. Spatial patterns from the 25-ha grid survey revealed that both P. pauciflorum and S. ventralis incidence were widespread. Phoradendron pauciflorum showed no spatial structure across the 25 ha but S. ventralis showed some degree of spatial structuring across the survey area. We also found that mistletoe severity was negatively correlated with regeneration of white fir. In pristine forests, pathogens and insects influence mortality and regeneration success, affecting stand structure and composition.

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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