Grey Trees Research Articles

Climate Change-Driven Cumulative Mountain Pine Beetle-Caused Whitebark Pine Mortality in the Greater Yellowstone Ecosystem

An aerial survey method called the Landscape Assessment System (LAS) was used to assess mountain pine beetle (Dendroctonus ponderosae)-caused mortality of whitebark pine (Pinus albicaulis) across the Greater Yellowstone Ecosystem (59,000 km2; GYE). This consisted of 11,942 km of flightlines, along which 4434 geo-tagged, oblique aerial photos were captured and processed. A mortality rating of none to severe (0–4.0 recent attack or 5.0–5.4 old attack) was assigned to each photo based on the amount of red (recent attack) and gray (old attack) trees visible. The method produced a photo inventory of 74 percent of the GYE whitebark pine distribution. For the remaining 26 percent of the distribution, mortality levels were estimated based on an interpolated mortality surface. Catchment-level results combining the photo-inventoried and interpolated mortality indicated that 44 percent of the GYE whitebark pine distribution showed severe old attack mortality (5.3–5.4 rating), 37 percent showed moderate old attack mortality (5.2–5.29 rating), 19 percent showed low old attack mortality (5.1–5.19 rating) and less than 1 percent showed trace levels of old attack mortality (5.0–5.09). No catchments were classified as recent attacks indicating that the outbreak of the early 2000’s has ended. However, mortality continues to occur as chronic sub-outbreak-level mortality. Ground verification using field plots indicates that higher LAS mortality values are moderately correlated with a higher percentage of mortality on the ground.

Shoulder Season

Shoulder Season

Spatial and temporal fuels changes in whitebark pine (Pinus albicaulis) from mountain pine beetle (Dendroctonus ponderosae)

Mountain pine beetle (MPB; Dendroctonus ponderosae Hopkins) causes extensive tree mortality in whitebark pine (Pinus albicaulis Engelm) forests. Previous studies conducted in lodgepole pine (Pinus contorta Douglas), Douglas-fir (Pseudotsuga menziesii (mirb.) Franco), and Engelmann spruce (Picea engelmanni Parry ex. Engelm) have shown that litter, duff, and 1-h (<0.64 cm) and 10-h (0.64–2.54 cm) time lag fuels are altered significantly from MPB outbreaks, while coarse woody fuels are affected over a longer time frame. MPB activity in conifer stands also alters foliar fuel moisture content over the course of the bark beetle rotation. This study evaluated changes to fine surface fuels and foliar fuel moisture in and under whitebark pine trees infested by MPB at two sites in Montana and Wyoming, USA. Fuel loads and foliar moisture were measured for crown condition classes of green trees (healthy), red trees (within two years since initial MPB attack with at least 50% of needles remaining), and gray trees (more than two years since attack with approximately 15% to 45% needles remaining). Tree locations and condition class were mapped using 2011, 2013, and 2015 NAIP imagery, and spatial point patterns were identified. Duff depths were significantly shallower beneath green trees (10.7–11.9 mm) than red (16.7–17.7 mm) and gray (13.9–16.1 mm) trees. Foliar fuel moisture content was altered dramatically across crown condition classes. Red needled trees had the lowest fuel moisture content, which was less than 18%. Point pattern hot spot analysis revealed increased (hot-spots) fuel hazard in trees 2–3 years post MPB attack, and decreased fuel hazard (cold-spots) in trees more than 3 years after MPB attack because foliage fell from trees and left larger diameter aerial fuels which were less likely to ignite. MPB-attacked trees were often clustered, and thus fuels hazard was not uniform across the landscape following MPB attack.

Effects of regulated deficit irrigation on soil salinity, physiological processes and fruit quality of gray jujube under desert conditions.

Regulated deficit irrigation (RDI) was applied to gray jujube trees in an oasis region, to determine the effects of this irrigation system on soil salinity, gray jujube physiological processes, fruit yield, and fruit quality. Treatments consisted of severe, moderate and low deficit irrigation (irrigated with 85%, 70% and 55% of CK, respectively) at the flowering stage to fruit set stage. During the other growth stages, all treatments were irrigated with 80% of pan evaporation, which was the same as that in control. The results indicated that soil salinity was enhanced during the periods of water stress, but the high value of soil salinity declined by 3.48%-37.27%, at each depth, after irrigation was resumed. RDI caused a decline in the photosynthetic rate, transpiration rate, and stomatal conductance, but enhanced the water use efficiency of the leaves. However, the leaf photosynthetic rate was effectively enhanced after the recovery of irrigation, especially in the moderate deficit irrigation treatment, which exceeded the control. This led to an improved fruit yield, which was 9.57% higher than that of the control. The deficit treatments caused a significant increase in the soluble solid content, soluble sugar content, single fruit weight and sugar/acid ratio. Enhanced vitamin C content, resulting from deficit treatments, has also been observed in the gray jujube. Therefore, this research shows that RDI provides some benefits in the production of gray jujube trees in desert conditions. Keywords: regulated deficit irrigation, soil salinity, gray jujube, water use efficiency, photosynthetic rate, transpiration rate, stomatal conductance, soluble solid content, sugar/acid ratio DOI: 10.25165/j.ijabe.20191203.4262 Citation: Liu Z P, Zhu C L, Wu S Y, Guo W H, Abudushalamu Y, Jiao X Y, et al. Effects of regulated deficit irrigation on soil salinity, physiological processes and fruit quality of gray jujube under desert conditions. Int J Agric & Biol Eng, 2019; 12(3): 52–59.

Extent of localized tree mortality influences soil biogeochemical response in a beetle-infested coniferous forest

Recent increases in the magnitude and occurrence of insect-induced tree mortality are disrupting evergreen forests globally. To resolve potentially conflicting ecosystem responses, we investigated whether surrounding trees exert compensatory effects on biogeochemical signatures following beetle infestation. To this end, plots were surveyed within a Colorado Rocky Mountain watershed that experienced beetle infestation almost a decade prior and contained a range of surrounding tree mortality (from 9 to 91% of standing trees). Near-surface soil horizons under plot-centered live (green) and beetle-killed (grey) lodgepole pines were sampled over two consecutive summers with variable moisture conditions. Results revealed that soil respiration was 18–28% lower beneath beetle-infested trees and correlated to elevated dissolved organic carbon aromaticity. While certain edaphic parameters including pH and water content were elevated below grey compared to green trees regardless of the mortality extent within plots, other biogeochemical responses required a higher severity of surrounding mortality to overcome compensatory effects of neighboring live trees. For instance, C:N ratios under grey trees declined with increased severity of surrounding tree mortality, and the proportion of ammonium displayed a threshold effect with pronounced increases after surrounding tree mortality exceeded ∼40%. Overall, the biogeochemical response to tree death was most prominent in the mineral soil horizon where tree mortality had the largest affect on carbon recalcitrance and the enrichment of nitrogen species. These results can aid in determining when and where nutrient cycles and biogeochemical feedbacks to the atmosphere and hydrosphere will be observed in association with this type of ecological disturbance.

Changes in metal mobility associated with bark beetle-induced tree mortality

Recent large-scale beetle infestations have caused extensive mortality to conifer forests resulting in alterations to dissolved organic carbon (DOC) cycling, which in turn can impact metal mobility through complexation. This study analyzed soil-water samples beneath impacted trees in concert with laboratory flow-through soil column experiments to explore possible impacts of the bark beetle infestation on metal release and transport. The columns mimicked field conditions by introducing pine needle leachate and artificial rainwater through duplicate homogenized soil columns and measuring effluent metal (focusing on Al, Cu, and Zn) and DOC concentrations. All three metals were consistently found in higher concentrations in the effluent of columns receiving pine needle leachate. In both the field and laboratory, aluminum mobility was largely correlated with the hydrophobic fraction of the DOC, while copper had the largest correlation with total DOC concentrations. Geochemical speciation modeling supported the presence of DOC-metal complexes in column experiments. Copper soil water concentrations in field samples supported laboratory column results, as they were almost twice as high under grey phase trees than under red phase trees further signifying the importance of needle drop. Pine needle leachate contained high concentrations of Zn (0.1 mg l(-1)), which led to high effluent zinc concentrations and sorption of zinc to the soil matrix representing a future potential source for release. In support, field soil-water samples underneath beetle-impacted trees where the needles had recently fallen contained approximately 50% more zinc as samples from under beetle-impacted trees that still held their needles. The high concentrations of carbon in the pine needle leachate also led to increased sorption in the soil matrix creating the potential for subsequent carbon release. While unclear if manifested in adjacent surface waters, these results demonstrate an increased potential for Zn, Cu, and Al mobility, along with increased deposition of metals and carbon beneath beetle-impacted trees.

An innovative aerial assessment of Greater Yellowstone Ecosystem mountain pine beetle‐caused whitebark pine mortality

An innovative aerial survey method called the Landscape Assessment System (LAS) was used to assess mountain pine beetle (MPB; Dendroctonus ponderosae)-caused mortality of whitebark pine (Pinus albicaulis) across the species distribution in the Greater Yellowstone Ecosystem (GYE; 894 774 ha). This large-scale implementation of the LAS method consisted of 8673 km of flight lines, along which 4653 geo-tagged, oblique aerial photos were captured at the catchment level (a subset of 12-digit USGS hydrologic units) and geographic information system (GIS) processed. The Mountain Pine Beetle-caused Mortality Rating System, a landscape-scale classification system designed specifically to measure the cumulative effects of recent and older MPB attacks on whitebark pine, was used to classify mortality with a rating from 0 to 6 based on the amount of red (recent attack) and gray (old attack) trees visible. The approach achieved a photo inventory of 79% of the GYE whitebark pine distribution. For the remaining 21%, mortality levels were estimated based on an interpolated surface. Results that combine the photo-inventoried and interpolated mortality indicate that nearly half (46%) of the GYE whitebark pine distribution showed severe mortality (3-4 or 5.3-5.4 rating), 36% showed moderate mortality (2-2.9 rating), 13% showed low mortality (1-1.9 rating), and 5% showed trace levels of mortality (0-0.9). These results reveal that the proliferation of MPB in the subalpine zone of the GYE due to climate warming has led to whitebark pine mortality that is more severe and widespread than indicated from either previous modeling research or USDA Forest Service Aerial Detection surveys. Sixteen of the 22 major mountain ranges of the GYE have experienced widespread moderate-to-severe mortality. The majority of catchments in the other six mountain ranges show low-to-moderate mortality. Refugia from MPB outbreaks, at least for now, also exist and correspond to locations that have colder microclimates. The spatially explicit mortality information produced by this project has helped forest managers develop and implement conservation strategies that include both preservation and restoration efforts. Future research aimed at documenting and quantifying the ecological impacts of widespread decline and collapse of this foundation and keystone species is warranted.

Landscape-scale analysis of aboveground tree carbon stocks affected by mountain pine beetles in Idaho

Bark beetle outbreaks kill billions of trees in western North America, and the resulting tree mortality can significantly impact local and regional carbon cycling. However, substantial variability in mortality occurs within outbreak areas. Our objective was to quantify landscape-scale effects of beetle infestations on aboveground carbon (AGC) stocks using field observations and remotely sensed data across a 5054 ha study area that had experienced a mountain pine beetle outbreak. Tree mortality was classified using multispectral imagery that separated green, red, and gray trees, and models relating field observations of AGC to LiDAR data were used to map AGC. We combined mortality and AGC maps to quantify AGC in beetle-killed trees. Thirty-nine per cent of the forested area was killed by beetles, with large spatial variability in mortality severity. For the entire study area, 40–50% of AGC was contained in beetle-killed trees. When considered on a per-hectare basis, 75–89% of the study area had >25% AGC in killed trees and 3–6% of the study area had >75% of the AGC in killed trees. Our results show that despite high variability in tree mortality within an outbreak area, bark beetle epidemics can have a large impact on AGC stocks at the landscape scale.

Half Life in the Half Light, and: After Infection

118 JASON LABBE HALF LIFE IN THE HALF LIGHT In spring snow it’s difficult to imagine, a bone broken for each year alive instantly maxing out wallets of credit cards. I couldn’t tell you the colors of emergency surgery, I can’t recall signing next to the X—because I never— and so promise to mispronounce pre-certification. I still pause before my name as though asked by a stranger in a dream to approach a black band of water at dusk. The day I glimpsed my X-ray of eighteen broken ribs I plotted to walk the thawing canal, to repeat that trail—it’s absurd—where a sign warns of hostile swans nesting. Today I hike through a squall, and without a hood, my head open to the buds and blossoms in shock. I receive a sky more static than gray, white noise of wind and vapor. I count eighteen sticks snap under my left steps, and I’m home. My fingers numb, I fumble with the light dimmer, then the stereo volume, and with eyes half-closed up my dosage of low frequencies, bass in the chest. Check below the ache in my sternum: I slept through the stitches and woke to a foot-long scar no one can tell me how I’ll pay for. What could I do but steal the scalpel. Now no traffic light halo, no rise in barometric pressure, and no path of black ice can strand me. This improvised power ballad whose words the world must misunderstand loops in my head, around my apartment, around the building, rides off the whitening curb, and laps 119 the block before skidding into a parked delivery truck. But the instrumental version blows straight out of the city and spreads into a colder fringe where my future house glows behind rows of gray trees. 120 JASON LABBE AFTER INFECTION To forget the year of fevers. To enter warm air, endless pathogens. Nothing sterile. The skin not so much a barrier as a membrane the mild breeze blows through. A decasecond of dusk is enough. Swollen sun coming down, the turkey vulture’s swoop behind the pines on the outskirts, all above moving closer to some out-of-view point of ground. To watch. To forget the Era of Lost Sleep after the promised guest never showed. A thin sweat is enough. ...

Balanced vertices in trees and a simpler algorithm to compute the genomic distance

This paper provides a short and transparent solution for the covering cost of white–grey trees which play a crucial role in the algorithm of Bergeron et al. to compute the rearrangement distance between two multichromosomal genomes in linear time (A. Bergeron, J. Mixtacki, J. Stoye, A new linear time algorithm to compute the genomic distance via the double cut and join distance, Theor. Comput. Sci. 410 (2009) 5300–5316). In the process it introduces a new center notion for trees, which seems to be interesting on its own.

Nest Site Selection by Western Gray Squirrels at Their Northern Range Terminus

The western gray squirrel (Sciurus griseus) in Washington, USA, is limited to 3 disjunct areas and is a state threatened species. Information is lacking for the North Cascades population, which is the northernmost population for the species. Squirrels in this population exist without oaks (Quercus spp.) that provide forage and cavities for maternal nests elsewhere in their range. During May 2003 to August 2005, we studied selection of nest sites and nest trees by 18 radiocollared squirrels in Okanogan County, Washington. Without oak cavities, females reared their young in dreys. General nest-tree characteristics were similar to characteristics of western gray squirrel nest trees in Southeastern Cascades: relatively tall ponderosa pines (Pinus ponderosa) ≥40 cm diameter at breast height. Results from conditional logistic models determined that the odds of a squirrel selecting a tree for nesting increased with greater diameter at breast height and with infection by dwarf mistletoe (Arceuthobium spp.). Nest sites with high selection probability by squirrels had greater basal area and number of tree species than available unselected sites. Retention of forest patches that include a mix of conifer species or conifer and deciduous trees and moderate to high basal area could promote nesting opportunities, connectivity for arboreal travel, as well as abundance and diversity of hypogeous fungi. Experiments to test the efficacy of retaining untreated patches of varying size (including trees infected with mistletoe) on nesting by western gray squirrels within stands managed for fire suppression and forest health would provide important information about the effects of forest fuel management on arboreal wildlife.

Ophiostomatoid and basidiomycetous fungi associated with green, red, and grey lodgepole pines after mountain pine beetle (Dendroctonus ponderosae) infestation

The mountain pine beetle (MPB) is a major concern for lodgepole pine (Pinus contorta var. latifolia Engelm.) forests in British Columbia, Canada. MPB and the ophiostomatoid staining fungi for which they serve as vector have a close, mutualistic relationship. In this work, we determined which fungi colonized MPB-killed standing trees with green, red, and grey crowns and quantified how rapidly the fungi stained and reduced the moisture content of sapwood. Green trees were mainly colonized by Ophiostoma clavigerum (Robinson-Jeffrey &amp; Davidson) Harrington, Ophiostoma montium (Rumbold) von Arx, Ophiostoma nigrocarpum (Davidson) De Hoog, Ophiostoma minutum (Olchow. &amp; Reid) Hausner, and unknown Leptographium species. In red and grey pines (2 and 3 years after the original MPB attack, respectively), the frequency of the original fungal colonizers decreased, and other sapstaining fungal species were encountered. Among basidiomycetous fungi, decay fungi were rarely present in green trees but were isolated more frequently in red and grey trees. The frequency and the type of decay fungi isolated varied between harvesting sites.

Tolerance of salinized floodplain conditions in a naturally occurring Eucalyptus hybrid related to lowered plant water potential.

Rising saline groundwater and reduced flooding frequency are causing dieback of Eucalyptus largiflorens F. Muell. along the Murray River in Australia. A green-leaved variant of E. largiflorens, which is probably a hybrid with a local mallee species (E. gracilis F. Muell.), tolerates saline conditions better than the more common grey-leaved variant. The green variant exhibited more negative water potentials than the grey variant, and comparison with soil water potential profiles indicated that the green variant extracted water from slightly higher up the soil profile where the salt content was lower but the soil was drier. However, the stable isotopes of water (2H and 18O) in the xylem did not differ significantly between paired green and grey trees, suggesting that both variants used the same water source. The green variant may be able to extract water for a longer period from a given point in the soil profile and tolerate a higher salt concentration around its roots than the grey variant. Predawn leaf water potentials of both variants decreased with increasing salinity of groundwater and decreasing depth to the groundwater, probably because the roots were being progressively confined to soil with lower matric potential as groundwater discharge through transpiration progressively salinized soil up the profile. The green variant had a lower assimilation rate and stomatal conductance than the grey variant, although the differences were not statistically significant during most of the year. Discrimination of 13C indicated that the green variant had a higher leaf internal CO2 concentration than the grey variant, indicative of a greater biochemical limitation on photosynthesis, perhaps resulting from the effects of operating at lower water potentials. The green variant had significantly lower stem hydraulic conductivity than the grey variant, probably because of its smaller xylem vessel diameter and higher degree of embolism. The more conservative water use of the green variant and its ability to operate at lower water potential than the grey variant appear to underlie its ability to tolerate conditions of reduced useable water above the saline groundwater. This advantage appears to outweigh the costs of increased xylem embolism and reduced assimilation.

Population Ecology of the Kamehameha Butterfly (Lepidoptera: Nymphalidae)

Mark-recapture studies of the endemic Hawaiian Kamehameha butterfly, Vanessa tameamea Eschscholtz, were conducted at five sites on Tantalus Mountain, Oahu, where adults fed on sap oozing from injured Acacia koa Gray (Mimosaceae) trees. Males outnumbered females at the sap fluxes by 4.5 to 1, but females accounted for 58% of 137 specimens collected at diverse sites during the last century. Thus, we infer that the proportion of time spent at sap fluxes was greater for males than females. Males showed high site fidelity; none of 51 recaptures of males were transfers between sites. Males' expected residence time was 16 d. The estimated number of males at the most intensively studied site varied from 13 to 36 during a 35-d period. On the island of Hawaii, a search of 16,360 leaves of Pipturus albidus (Hooker & Arnott) Gray (Urticaceae), the primary larval host plant, yielded one larva of V. tameamea . Although habitat destruction may have reduced the distribution of V. tameamea , results suggest that food for larvae is not a limiting resource for extant populations.

The Play

.,vvvv.,,,v.,..vv.,.,l ............................s ^ The Play 2,>¿¿¿- by Ron Willoughby ->, J . She was nearly home now. Jean turned the VW onto a hump-backed road that twisted through a tunnel of winter-bare trees as it followed Wolf Creek up the narrow hollow. As the familiar landscape flowed by she began , in spite of herself, to think of her father. She saw his long angular face, set on a spare body kept lean by a lifetime of work in the mines. His stern, impassive face, lined with years. He had been cool and aloof, she remembered seldom smiling or showing emotion of any kind. And now he was dead. "Well," she thought, "at least 111 only miss two or three rehearsals. Two weeks later and I'd have missed performances." Jean thought of herself as a professional actress, though in three years in New York she had failed to land a speaking part. Finally she had taken a job at a small Virginia college, teaching English and drama and acting in¦campus productions and little theatre. She didn't particularly like teaching, but it supported her acting habit. She was driving the winding road 34 by memory, wheeling the VW expertly through the turns. Suddenly a squirrel darted across the road in front of her. "Get the hell out of the way!" she muttered , yanking the steering wheel hard, and the car veered into the next turn. Near its head the hollow was wide enough for a single row of thirty-two drab frame houses along the base of the ridge to the left. Right in front of the houses ran a railroad track, with the rocky creek beside it. The road ran along the base of the other mountain, perhaps one hundred feet from the creek. This was Kenro, the mining camp where Jean had grown up and where her parents had lived their adult lives. Jean parked by the run-down little schoolhouse she had attended as a child, got out of the car and stretched. She pulled her coat tightly about her thin shoulders, tugged the hood over her short brown hair, and crossed the creek on the wooden footbridge, footsteps echoing hollowly. The mountains loomed over her, covered with skeletal gray trees and blotched with patches of dirty snow. The indifferent winter sunlight did not warm her as she walked along the railroad tracks to her parents' house. Jean went straight to the kitchen. Her mother burst into tears and ran to embrace her, while two neighbors clucked sympathetically and patted both women on the shoulder. When her mother had composed herself, Jean turned to greet the neighbors , Mrs. Bell and Mrs. Thane, and they passed a minute in small talk. Then Mrs. Bell suggested that they go into the living room to see her father's body. "Is he here?" Jean asked, surprised. "Yes," said her mother, brushing her hands across her cheeks to wipe away the tears. "Your father wanted it that way." "Oh my God," thought Jean, "that sort of thing went out of style twenty years ago, even here. 1 don't believe this." But she was trapped, so she walked through the house toward the living room, which opened off the hall at the front of the house. Entering the room, Jean saw the gray metal casket, lid open, surrounded by flowers. A funeral home phonograph played organ music. The heavy odor of flowers took her breath as she stood by the casket and looked dutifully down at her father. He lay there, diminished in death, and she was surprised to realize that she was not sad, but angry. Thinking that Jean wouldn't hear her over the music, Mrs. Bell whispered, "Not a tear. Isn't that something?" Not caring whether she was overheard or not, Mrs. Thane tilted her head back and sniffed. "She's just like her father," she whispered loudly. "Cold as ice." Jean turned and left the room, pretending that she had not heard. On the morning óf the funeral Jean came downstairs early. She had been wrestling with her feelings for the past two nights and hadn't slept much. 35 It was still...