Initial tree mortality and insect and pathogen response to fire and thinning restoration treatments in an old-growth mixed-conifer forest of the Sierra Nevada, California

Fire and thinning restoration treatments in fire-suppressed forests often damage or stress leave trees, altering pathogen and insect affects. We compared types of insect- and pathogen-mediated mortality on mixed-conifer trees 3 years after treatment. The number of bark beetle attacked trees was greater in burn treatments compared with no-burn treatments, and in some cases, larger pine trees were preferentially attacked. Restoration treatments are not expected to change the trajectory of spread and intensification of dwarf mistletoe. Thinning treatments may have provided a sanitation effect in which large leave trees have lower levels of dwarf mistletoe. Although thinning treatments are known to exacerbate root disease, <12% of cut stumps were infected with root pathogens ( Armillaria gallica and Heterobasidion annosum ). Treatments increased Ribes (alternate host for white pine blister rust) frequency and abundance, which may have very localized impacts on white pine blister rust dynamics. In some instances, fire, insects, and pathogens appear to conflict with forest restoration goals by reducing the percentage of pine and producing proportionally higher rates of tree mortality in large-diameter size classes. To better understand the long-term effects of restoration treatments on pathogens and insects, continued monitoring over the course of varying climatic conditions will be needed.

Download Full-text

Implementation constraints limit benefits of restoration treatments in mixed-conifer forests

International Journal of Wildland Fire ◽

10.1071/wf18141 ◽

2019 ◽

Vol 28 (7) ◽

pp. 495 ◽

Cited By ~ 6

Author(s):

Jamie M. Lydersen ◽

Brandon M. Collins ◽

Carolyn T. Hunsaker

Keyword(s):

Sierra Nevada ◽

Forest Structure ◽

Forest Restoration ◽

Tree Mortality ◽

Canopy Cover ◽

Basal Area ◽

Severe Drought ◽

Conifer Forest ◽

Mixed Conifer ◽

Trade Offs

Forest restoration treatments seek to increase resilience to wildfire and a changing climate while avoiding negative impacts to the ecosystem. The extent and intensity of treatments are often constrained by operational considerations and concerns over uncertainty in the trade-offs of addressing different management goals. The recent (2012–15) extreme drought in California, USA, resulted in widespread tree mortality, particularly in the southern Sierra Nevada, and provided an opportunity to assess the effects of restoration treatments on forest resilience to drought. We assessed changes in mixed-conifer forest structure following thinning and understorey burning at the Kings River Experimental Watersheds in the southern Sierra Nevada, and how treatments, topography and forest structure related to tree mortality in the recent drought. Treatments had negligible effect on basal area, tree density and canopy cover. Following the recent drought, average basal area mortality within the watersheds ranged from 5 to 26% across riparian areas and 12 to 44% across upland areas, with a range of 0 to 95% across all plots. Tree mortality was not significantly influenced by restoration treatments or topography. Our results suggest that the constraints common to many restoration treatments may limit their ability to mitigate the impacts of severe drought.

Download Full-text

Whitebark pine and white pine blister rust in British Columbia, Canada

Canadian Journal of Forest Research ◽

10.1139/x02-049 ◽

2002 ◽

Vol 32 (7) ◽

pp. 1265-1274 ◽

Cited By ~ 36

Author(s):

Stefan Zeglen

Keyword(s):

British Columbia ◽

Mountain Pine Beetle ◽

Tree Mortality ◽

Abies Lasiocarpa ◽

Whitebark Pine ◽

White Pine Blister Rust ◽

White Pine ◽

Blister Rust ◽

Dead Trees ◽

Mortality Incidence

A survey of the health of whitebark pine (Pinus albicaulis Engelm.) was conducted throughout its range in British Columbia, Canada. Over 3 years, 24 070 trees were examined for mortality, incidence of white pine blister rust (Cronartium ribicola J.C. Fisch.), or other damage. About 19% of whitebark pine (>1.3 m in height) were dead, and another 31% had active blister rust infections. Tests of relationships between the proportion of healthy, infected, or dead trees and elevation, latitude, and longitude produced mixed results. The ratio of healthy to infected whitebark pine varies considerably across the province, with a trend of increasing incidence from west to east. Losses to mountain pine beetle (Dendroctonus ponderosae Hopkins) proved minor, but bark stripping by mammals was common. Whitebark pine seedlings (<1.3 m in height) revealed lower rates of mortality (11%) and rust infection (4%) than larger trees. However, the pioneer species whitebark pine was found in less than half the regeneration plots and was usually outnumbered by subalpine fir (Abies lasiocarpa (Hook.) Nutt.). The combination of mature tree mortality, lack of suitable substrate for regeneration, and the incursion of climax species indicates a continued decline in whitebark pine populations in British Columbia.

Download Full-text

Whitebark and Foxtail Pine in Yosemite, Sequoia, and Kings Canyon National Parks: Initial Assessment of Stand Structure and Condition

Forests ◽

10.3390/f10010035 ◽

2019 ◽

Vol 10 (1) ◽

pp. 35 ◽

Cited By ~ 7

Author(s):

Jonathan C.B. Nesmith ◽

Micah Wright ◽

Erik S. Jules ◽

Shawn T. McKinney

Keyword(s):

Sierra Nevada ◽

National Parks ◽

Mountain Pine Beetle ◽

Whitebark Pine ◽

White Pine Blister Rust ◽

White Pine ◽

Blister Rust ◽

Mountain Pine ◽

Pine Beetle ◽

Foxtail Pine

The Inventory & Monitoring Division of the U.S. National Park Service conducts long-term monitoring to provide park managers information on the status and trends in biological and environmental attributes including white pines. White pines are foundational species in many subalpine ecosystems and are currently experiencing population declines. Here we present results on the status of whitebark and foxtail pine in the southern Sierra Nevada of California, an area understudied relative to other parts of their ranges. We selected random plot locations in Yosemite, Sequoia, and Kings Canyon national parks using an equal probability spatially-balanced approach. Tree- and plot-level data were collected on forest structure, composition, demography, cone production, crown mortality, and incidence of white pine blister rust and mountain pine beetle. We measured 7899 whitebark pine, 1112 foxtail pine, and 6085 other trees from 2012–2017. All factors for both species were spatially highly variable. Whitebark pine occurred in nearly-pure krummholz stands at or near treeline and as a minor component of mixed species forests. Ovulate cones were observed on 25% of whitebark pine and 69% of foxtail pine. Whitebark pine seedlings were recorded in 58% of plots, and foxtail pine seedlings in only 21% of plots. Crown mortality (8% in whitebark, 6% in foxtail) was low and significantly higher in 2017 compared to previous years. Less than 1% of whitebark and zero foxtail pine were infected with white pine blister rust and <1% of whitebark and foxtail pine displayed symptoms of mountain pine beetle attack. High elevation white pines in the southern Sierra Nevada are healthy compared to other portions of their range where population declines are significant and well documented. However, increasing white pine blister rust and mountain pine beetle occurrence, coupled with climate change projections, portend future declines for these species, underscoring the need for broad-scale collaborative monitoring.

Download Full-text

The influence of white pine blister rust on seed dispersal in whitebark pine

Canadian Journal of Forest Research ◽

10.1139/x06-305 ◽

2007 ◽

Vol 37 (6) ◽

pp. 1044-1057 ◽

Cited By ~ 31

Author(s):

Shawn T. McKinney ◽

Diana F. Tomback

Keyword(s):

Seed Dispersal ◽

Tree Mortality ◽

Whitebark Pine ◽

White Pine Blister Rust ◽

White Pine ◽

Infection Level ◽

Successional Stage ◽

Seed Predator ◽

Seed Survival ◽

Blister Rust

We tested the hypotheses that white pine blister rust ( Cronartium ribicola J.C. Fisch.) damage in whitebark pine ( Pinus albicaulis Engelm.) stands leads to reduced (1) seed cone density, (2) predispersal seed survival, and (3) likelihood of Clark’s Nutcracker ( Nucifraga columbiana (Wilson, 1811)) seed dispersal. We gathered data from two sets of paired forest sites in the Bitterroot Mountains of eastern Idaho and western Montana that were similar in topography, canopy structure, tree species composition, and successional stage, but differed in rust infection level, crown kill, and tree mortality. We counted initial (mid-July) and final (late August) seed cones, observed vertebrate seed predator activity, and documented nutcracker seed dispersal in study sites in 2001 and 2002. High-rust sites had higher rates of seed predation relative to cone abundance, lower predispersal seed survival, and fewer observations of nutcracker seed dispersal than paired low-rust sites. These findings suggest that as blister-rust-induced damage increases within stands in the Bitterroot Mountains, the likelihood of nutcracker seed dispersal decreases. We propose that whitebark pine in heavily rust-damaged forests may not self-regenerate and would therefore require planting of seeds or seedlings from genetically rust-resistant trees.

Download Full-text

First Report of White Pine Blister Rust in Nevada

Plant Disease ◽

10.1094/pdis.2000.84.5.594a ◽

2000 ◽

Vol 84 (5) ◽

pp. 594-594 ◽

Cited By ~ 4

Author(s):

J. P. Smith ◽

J. T. Hoffman ◽

K. F. Sullivan ◽

E. P. Van Arsdel ◽

D. Vogler

Keyword(s):

Sierra Nevada ◽

Great Basin ◽

Lake Tahoe ◽

White Pine Blister Rust ◽

White Pine ◽

Infection Age ◽

Blister Rust ◽

Infection Dynamics ◽

Stem Cankers ◽

Region Ii

White pine blister rust, caused by Cronartium ribicola Fisch., was found in 1997 infecting white pines (genus Pinus, subgenus Strobus) at two locations in the Carson Range of western Nevada. Rust incidence, infection age, damage to trees, rust phenology, and host distribution were evaluated at one of these locations and a nearby location in California in 1998. At the first location (39.3°N, 119.9°W), C. ribicola was found infecting 24 of 49 whitebark pines (P. albicaulis Engelm.) near Mt. Rose Summit on Highway 27 at 2,710 m elevation, ≈6 km northeast of Incline Village, Washoe County, NV. Among infected trees, 33% had only branch cankers, 54% had live stem cankers, and 12% had stem cankers that had killed portions of trees distal to cankers. No trees had died from infection. At the second location (39.1°N, 119.9°W), we found only 6 of 50 (12%) infected western white pines (P. monticola Dougl.) near Genoa Peak (≈2,750 m elevation), 3 km east of Lake Tahoe, Douglas County, NV; however, stem cankers occurred on 4 of the 6 infected trees. In September 1998, whitebark pines at Mt. Rose and Tahoe Meadows (2,550 m elevation, 1.5 km southwest of Mt. Rose Summit) were examined, and the following was observed: (i) aeciospore production was at its peak, indicating that sporulation can occur exceptionally late in the season in this region; (ii) signs of blister rust infection were absent on the telial hosts of C. ribicola (Ribes cereum, R. montigenum, and R. nevadense) at both locations; (iii) ≈80% of the cankers occurred on host wood produced in 1978 and 1979; and (iv) the oldest cankers originated on wood produced in 1968 and the youngest on wood produced in 1980. In October 1998, infected western white pines were examined at a location (2,650 m elevation) ≈30 km north of Lake Tahoe on Babbitt Peak, Sierra County, CA (39.6°N, 120.1°W). At this location, no trees had died from infection, fresh aeciospores were abundant on live cankers, R. montigenum and R. cereum were present but did not show signs of infection, and 19 of 20 cankers examined were on wood produced between 1978 and 1980. White pine blister rust was not found at any of 10 other locations examined throughout Nevada from 1995 to 1997. This is believed to be the first documented report of C. ribicola infecting white pines in Nevada and the easternmost extension of blister rust in the Sierra Nevada Region. These observations suggest that our understanding of blister rust spread and infection dynamics east of the Sierra Nevada crest is incomplete and that future surveys and research in this region must address, among other issues, timing of aeciospore production on pine, and the possibility of blister rust spread into the Great Basin.

Download Full-text

Distribution and frequency of a gene for resistance to white pine blister rust in natural populations of sugar pine

Canadian Journal of Botany ◽

10.1139/b92-165 ◽

1992 ◽

Vol 70 (7) ◽

pp. 1319-1323 ◽

Cited By ~ 34

Author(s):

Bohun B. Kinloch Jr.

Keyword(s):

Sierra Nevada ◽

Genetic Resistance ◽

Natural Populations ◽

Close Relative ◽

Cronartium Ribicola ◽

White Pine Blister Rust ◽

White Pine ◽

Blister Rust ◽

Single Leaf ◽

Sugar Pine

The gametic frequency of a dominant allele (R) for resistance to white pine blister rust, a disease caused by an introduced pathogen (Cronartium ribicola), in natural populations of sugar pine was estimated by the kind of leaf symptom expressed after artificial inoculation of wind-pollinated seedlings from susceptible seed–parent genotypes (rr). Gene frequency increased clinally from near 0 in the southern Cascade Range to 0.08 in the southern Sierra Nevada, but it was not correlated with any major climatic gradient. Because R expresses a typical hypersensitivity response to pathogenesis, it has probably always functioned in disease resistance. A candidate pathogen for this function is C. occidentale, cause of pinyon blister rust, and a close relative of C. ribicola. Increase in allele frequency was positively associated with the proximity of sugar pine to single-leaf pinyon pine populations. Although sugar pine is not presently a natural host of pinyon rust, R may be a relict gene that protected sugar pine from this endemic pathogen in recent geologic epochs, when both pines are known to have been more intimately associated. Key words: Cronartium ribicola, genetic resistance, Pinus lambertiana, population genetics.

Download Full-text

Origin and Distribution of Cr2, a Gene for Resistance to White Pine Blister Rust in Natural Populations of Western White Pine

Phytopathology ◽

10.1094/phyto.2003.93.6.691 ◽

2003 ◽

Vol 93 (6) ◽

pp. 691-694 ◽

Cited By ~ 27

Author(s):

Bohun B. Kinloch ◽

Richard A. Sniezko ◽

Gayle E. Dupper

Keyword(s):

Sierra Nevada ◽

Natural Populations ◽

The United States ◽

Hypersensitive Reaction ◽

White Pine Blister Rust ◽

Pinus Monticola ◽

White Pine ◽

Blister Rust ◽

Sugar Pine ◽

Western White Pine

The distribution and frequency of the Cr2 gene for resistance to white pine blister rust (Cronartium ribicola) in western white pine (Pinus monticola) was surveyed in natural populations of the host by inoculation of open-pollinated seedlings from 687 individual seed parents from throughout most of the species' range. Because Cr2 is dominant and results in a conspicuous hypersensitive reaction (HR) in pine needles, the phenotype can readily be detected in offspring of susceptible seed parents fertilized by unknown Cr2 donors in the ambient pollen cloud. Gametic frequencies of Cr2 were thus determined as the proportion of total challenged seedlings that were pollen receptors exhibiting the Cr2 phenotype. Zygotic frequencies, the proportion of seed parents with progeny that segregated in Mendelian ratios for the Cr2 phenotype to the total number of parents, were a complementary, though less precise, measure. Cr2 frequency was rare overall, ranging from 0.004 to 0.008 in the Sierra Nevada to about 0.001 in the central Cascade Range; it was undetectable further north in the Cascades, as well as in the Rocky Mountains and Coast Mountains of the United States and Canada. The diminishing frequency of Cr2 from the southern and central Sierra Nevada northward mirrors that of Cr1 in sugar pine (P. lambertiana) and points to this region as the origin of both genes. We rationalize that this coincidence may have resulted from protection that these genes may have conferred on both species to an endemic pine stem rust congeneric with C. ribicola (C. occidentale) in recent geologic epochs.

Download Full-text