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RUSSIAN JOURNAL OF FOREST SCIENCE, 2021, No. 4, P. 406–414 MORPHOMETRIC PARAMETERS OF THE SCOTS PINE ASSIMILATION APPARATUS IN THE MOUNTAINS OF THE CENTRAL CAUCASUS M. Z. Mollaeva Institute of Ecology of Mountain Territories I. Armand st. 37-a, Nal’chik 360000, Kabardino-Balkaria republic, Russia E-mail: monika.011@yandex.ru Received 09 June 2020 In this work, for the first time for the Caucasus, Central in particular, the data on the Scots pine Pinus sylvestris L. assimilation apparatus morphological variability (length, width, lifespan, and weight of needles, length of annual growth and needle packing) are presented in cenopopulations growing on different altitudes. According to the results of the study, the longest needles were observed in the Baksan Gorge, where, in the high altitude conditions (>1900 m), there is a clear trend towards decreasing the length of needles with the inceasing altitudes; the shortest being found in the gorge of the river Malka. The needle mass in the studied samples of Scots pines from different altitudes varies significantly; there was no connection found between this parameter and the height of the growing areas. The length of the annual shoot in the studied Pinus sylvestris cenopopulations ranges from 59 mm at an altitude of 1200 m and up to 30 mm at an altitude of 2500 m, i.e. with an altitude increase it decreases in length by almost 2 times. With an increase in the altitude gradient in the study area, a decrease in the length of pine needles (r = -0.50 with p = 0.005) and shoot (r = -0.54 with p = 0.005) was observed, which is consistent with the literature data. The needle packing index in the studied pine samples varied from 0.65 ± 0.04 (Verkhniy Baksan) to 0.91 ± 0.04 (Khabaz); no correlation was found between the needle packing and the height gradient (r = 0.21). The lifespan of needles in pine populations growing on different altitudes in the Central Caucasus is on average 3-4 years, with the exception of the Cheget sample, where needles up to 6 years old have been observed. Key words: Pinus sylvestris L., length and width of needles, lifespan and mass of needles, length of the shoot and needle packing, populations from different altitudes, Central Caucasus. DOI: 10.31857/S0024114821040082 REFERENCES Abramova L.P., Zalesov S.V., Kharakteristika assimilyatsionnogo apparata predvaritel'nykh kul'tur sosny obyknovennoi v zavisimosti ot polnoty berezovogo drevostoya (Characteristics of the assimilation apparatus of preliminary crops of Scots pine, depending on the completeness of the birch stand), In: Lesa Urala i khozyaistvo v nikh (Forests of Urals and the management), Ekaterinburg: Ural. gos. lesotekhn. un-t, 2002, Vol. 22, pp. 149–151. 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To examine the potential mechanistic predictors of germination and first-year survival in two species of Great Basin sub-alpine trees along an elevation gradient on three soil types. Using a network of experimental gardens, we sowed limber pine and Great Basin bristlecone pine along elevational gradients at three sites on three different soil types. We collected germination and first-year survival data of each species while measuring temperature, soil water content, and other environmental variables to examine the potential predictors of first-year survival in these two species. Thanks to consecutive anomalously wet and dry years, we found germination and first-year survival to be largely limited by soil type, soil water content, and precipitation timing. Limber pine germination and survival showed weak negative responses while bristlecone pine germination and survival showed stronger negative responses to temperature. Young trees are more sensitive to water limitation than to temperature and soil type has a strong moderating effect on water availability. Precipitation timing affected this availability with winter snowpack being less important in establishment than summer monsoonal rain. These results point to the importance of substrate and understanding limitations on all life stages when attempting to predict species range shifts.

Great Basin bristlecone pine (Pinus longaeva D.K. Bailey) is an important and long-lived tree species found at high elevations in the interior southwest of the United States, but little is known about its regeneration requirements and response to disturbance. We conducted extensive surveys of seedling regeneration and environmental attributes of regeneration sites in undisturbed forest dominated by this species in the Spring Mountains of southern Nevada. Additional surveys tallied new seedling densities and site attributes 4 years after a wildfire in the same area. Seedlings, saplings, and juvenile trees were less abundant than adult trees in the unburned forest, and soils had lower bulk density and greater depth, moisture, and soil organic matter under adult trees than in open areas. Seedling distributions in both unburned and burned forest showed a negative relationship to a heat load index governed by aspect. The density of new seedlings after the fire was negatively related to distance from unburned forest edges. Seedlings were found in clusters and were associated with adult trees (live or dead) in both unburned and burned stands. Seedling emergence from animal-dispersed caches was more frequent in burned habitats than in unburned habitats. These natural regeneration dynamics provide potential guidance for restoration efforts in this ecosystem.

In 2018 Pearson et al. published a new sequence of annual radiocarbon (14C) data derived from oak (Quercus sp.) trees from Northern Ireland and bristlecone pine (Pinus longaeva) from North America across the period 1700–1500 BC. The study indicated that the more highly resolved shape of an annually based calibration dataset could improve the accuracy of 14C calibration during this period. This finding had implications for the controversial dating of the eruption of Thera in the Eastern Mediterranean. To test for interlaboratory variation and improve the robustness of the annual dataset for calibration purposes, we have generated a replicate sequence from the same Irish oaks at ETH Zürich. These data are compatible with the Irish oak 14C dataset previously produced at the University of Arizona and are used (along with additional data) to examine inter-tree and interlaboratory variation in multiyear annual 14C time-series. The results raise questions about regional 14C offsets at different scales and demonstrate the potential of annually resolved 14C for refining subdecadal and larger scale features for calibration, solar reconstruction, and multiproxy synchronization., Radiocarbon, 62 (4), ISSN:0033-8222, IntCal20: Calibration Issue

1. In response to contemporary changes in climate, many tree species are shifting upslope to find favorable habitat. In the case of obligate ectomycorrhizal species, seedling growth above upper treeline depends on fungal spore availability. In the mountain ranges of the Great Basin, a recent shift in tree species stratification has been recorded, with limber pine (LP, Pinus flexilis) leapfrogging above the ancient bristlecone pine (BCP, Pinus longaeva) forest and establishing above current treeline. 2. We compared the ability of LP and BCP to interact with soil spore banks collected at different microhabitats (next to dead trees, young live trees or in a treeless control) above current treeline in the White Mountains of California. 3. We found an ectomycorrhizal fungal spore bank community composed of 15 species that was dominated by an undescribed and a hitherto unsequenced species of Geopora and Rhizopogon, respectively. This represents a much richer community than was found previously in this system. While both LP and BCP were able to establish ectomycorrhiza, LP was twice as likely to do so, and when comparing only seedlings that were colonized, its root system was colonized to a three‐fold greater extent. BCP seedlings grown on soils collected under young live trees were much more likely to be colonized compared to soils from the other two microhabitats. 4. Synthesis. These differences in ectomycorrhizal receptivity might help to explain why LP is currently establishing at higher rates above the BCP treeline. Furthermore, it is possible that LP saplings above treeline can provide ectomycorrhizal facilitation for BCP seedlings, enabling the subsequent shift of BCP above treeline.

The article presents the first direct evidence of the influence of supernova flashes on the biosphere. Geochemistry and paleontology have not yet provided convincing data on the life response to disasters in the Milky Way Galaxy. This gap was eliminated through tree ring analysis of bristlecone pine from the Cordilleras responded to seven supernova outbursts in 185-1604 AD. The author used the superposed epoch method to process data at the 11 longest dendrochronologies, based on the results of measurement of annual growth of about 300 trees. The main finding is the growth depression in high-mountain population caused by supernova outbursts lasted for 20 - 30 years after the event. Moreover, in most cases, drastic growth reduction occurred one year prior to the event. In some cases, the annual tree ring increment exceeded the normal range many years after the event, and, consequently, it could be concluded that plant response was associated with the ozone layer depletion.

The annual 14C data in tree rings is an outstanding proxy for uncovering extreme solar energetic particle (SEP) events in the past. Signatures of extreme SEP events have been reported in 774/775 CE, 992/993 CE, and ∼660 BCE. Here, we report another rapid increase of 14C concentration in tree rings from California, Switzerland, and Finland around 5410 BCE. These 14C data series show a significant increase of ∼6‰ in 5411–5410 BCE. The signature of 14C variation is very similar to the confirmed three SEP events and points to an extreme short‐term flux of cosmic ray radiation into the atmosphere. The rapid 14C increase in 5411/5410 BCE rings occurred during a period of high solar activity and 60 years after a grand 14C excursion during 5481–5471 BCE. The similarity of our 14C data to previous events suggests that the origin of the 5410 BCE event is an extreme SEP event., Key Points Rapid 14C increase of ∼6‰ with significant level was found in tree rings from California, Switzerland, and Finland around 5410 BCEFive thousand, four hundred ten BCE event occurred during a period of high solar activity and 60 years after a grand 14C excursion of ∼20‰ from 5481 to 5471 BCEThe similarity of this 14C signature to already known solar events suggests that the origin of this new 5410 BCE event is an extreme SEP

Mountain pine beetle (MPB) (Dendroctonus ponderosae Hopkins) is a native bark beetle that reproduces in pine (Pinus) species across western North America. High population levels can result in widespread host tree mortality. Over the past 2 decades, MPB has been responsible for pine mortality across millions of forested hectares in the western United States. Although a majority of the pine species found in the western United States are considered hosts to MPB, the host status of Rocky Mountain (RM) bristlecone pine (Pinus aristata) is unclear. We surveyed stands across the range of RM bristlecone pine in Colorado, USA, and quantified MPB-caused mortality within the past 10 years in stands where RM bristlecone and at least one other pine species co-occurred. We also evaluated in the field whether successful MPB brood production occurred in RM bristlecone pine. Our results confirm that RM bristlecone pine is susceptible to MPB attack and suitable for MPB reproduction. In mixed-species stands, pine species availability influenced MPB attack occurrence. The proportion of trees experiencing fatal beetle attack within a particular Pinus species was best predicted by the basal area proportion of that species in the stand prior to the most recent 10 years of mortality. These results indicate that RM bristlecone pine is vulnerable to ongoing climate change–induced contact with MPB.

Edmund Schulman is rightly honored for quantifying the age of bristlecone pines and discovering individuals significantly older than giant sequoias (Sequoiadendron gigantea), previously thought to be the oldest living things. However, George Engelmann inferred the potential for great age in his description of bristlecone pine (Pinus aristata) almost a century before, in 1863. Staff from Inyo National Forest re-made Engelmann's inference, and publically asserted that White Mountain bristlecones might outlive giant sequoias before Schulman had published any results of his bristlecone research.Schulman sampled White Mountains pines after seeing a photograph and caption associated with an article by founders of the University of California White Mountain Research Station. Although Schulman's correspondence and publications make this clear, incorrect theories regarding his decision to come to the White Mountains have been published and are promulgated at the Schulman Grove Visitor Center in the White Mountains. This paper places Schulman's work in its historic context by recovering forgotten information about attempts by Inyo National Forest staff and White Mountain Research Station to call attention to the trees. It also recovers details of Schulman's and C. Wesley Ferguson's activities in the White Mountains range as documented in field notes and Thomas Harlan's Bristlecone Pine Project database.

Great Basin Bristlecone pine (Pinus longaeva) is known for its longevity. The longest continuous tree-ring width chronology covers more than 9000 years. Tree-ring width of upper treeline bristlecone pine trees is influenced by summer temperature variability at decadal to centennial scales, but to infer a temperature signal on interannual scales, Maximum Latewood Density (MXD) is a better proxy. Here, we present a preliminary MXD chronology to investigate the temperature signal in upper treeline and lower elevation bristlecone pines. MXD was measured with an X-ray Computed Tomography toolchain in 24 dated cores, with the oldest sample dating back to 776 CE. Ring and fibre angles were corrected and two MXD chronologies for different elevations were developed, which will be used to study climate-growth relationships and the effect of elevation on them. Future scanning will allow constructing a 5000+ year-long MXD chronology from upper treeline sites, which will provide an annual-resolution North American temperature record covering the mid-to-late Holocene.

As part of the ongoing effort to improve the Northern Hemisphere radiocarbon (14C) calibration curve, this study investigates the period of 856 BC to 626 BC (2805–2575 yr BP) with a total of 403 single-year 14C measurements. In this age range, IntCal13 was constructed largely from German and Irish oak as well as Californian bristlecone pine 14C dates, with most samples measured with a 10-yr resolution. The new data presented here is the first atmospheric 14C single-year record of the older end of the Hallstatt plateau based on an absolutely dated tree-ring chronology. The data helped reveal a major solar proton event (SPE) which caused a spike in the production rate of cosmogenic radionuclides around 2610/2609 BP. This production event is thought to have reached a magnitude similar to the 774/775 AD production event but has remained undetected due to averaging effects in the decadal calibration data. The record leading up to the 2610/2609 BP event reveals a 11-yr solar cycle with varying cyclicity. Features of the new data and the benefits of higher resolution calibration are discussed.

Great Basin Bristlecone pine (Pinus longaeva) is known for its trees that attain old age. The longest chronology is more than 9000 years long, and the temperature-sensitive upper treeline chronology extends back to 5000 years. The ring width pattern of upper treeline bristlecone pine trees are strongly influenced by temperature variability at decadal to centennial scales. To infer a climate signal on annual scales, MXD is shown to be a better temperature proxy. Here, we present a preliminary Maximum Latewood Density (MXD) chronology of bristlecone pine to investigate the temperature signal in upper treeline and below. Maximum latewood density (MXD) from 24 dated cores (from various sites ranging from the upper treeline and below, oldest sample dates back to 776 AD) was determined with an X-ray CT toolchain. Ring and fibre angles were corrected and a MXD chronology was constructed. The resulting MXD chronology will be correlated to summer temperature. Future scanning will allow constructing a + 5000 year MXD chronology and could reveal the cooling effect of volcanic eruptions through this period.

Calendar-dated tree-ring sequences offer an unparalleled resource for high-resolution paleoenvironmental reconstruction. Where such records exist for a few limited geographic regions over the last 8,000 to 12,000 years, they have proved invaluable for creating precise and accurate timelines for past human and environmental interactions. To expand such records across new geographic territory or extend data for certain regions further backward in time, new applications must be developed to secure “floating” (not yet absolutely dated) tree-ring sequences, which cannot be assigned single-calendar year dates by standard dendrochronological techniques. This study develops two approaches to this problem for a critical floating tree-ring chronology from the East Mediterranean Bronze–Iron Age. The chronology is more closely fixed in time using annually resolved patterns of 14C, modulated by cosmic radiation, between 1700 and 1480 BC. This placement is then tested using an anticorrelation between calendar-dated tree-ring growth responses to climatically effective volcanism in North American bristlecone pine and the Mediterranean trees. Examination of the newly dated Mediterranean tree-ring sequence between 1630 and 1500 BC using X-ray fluorescence revealed an unusual calcium anomaly around 1560 BC. While requiring further replication and analysis, this anomaly merits exploration as a potential marker for the eruption of Thera., Proceedings of the National Academy of Sciences of the United States of America, 117 (15), ISSN:0027-8424, ISSN:1091-6490

Flowering, the beginning of the reproductive growth, is a significant stage in the growth and development of plants. Conifers are economically and ecologically important, characterized by straight trunks and a good wood quality and, thus, conifer plantations are widely distributed around the world. In addition, conifer species have a good tolerance to biotic and abiotic stress, and a stronger survival ability. Seeds of some conifer species, such as Pinus koraiensis, are rich in vitamins, amino acids, mineral elements and other nutrients, which are used for food and medicine. Although conifers are the largest (giant sequoia) and oldest living plants (bristlecone pine), their growth cycle is relatively long, and the seed yield is unstable. In the present work, we reviewed selected literature and provide a comprehensive overview on the most influential factors and on the methods and techniques that can be adopted in order to improve flowering and seed production in conifers species. The review revealed that flowering and seed yields in conifers are affected by a variety of factors, such as pollen, temperature, light, water availability, nutrients, etc., and a number of management techniques, including topping off, pruning, fertilization, hormone treatment, supplementary pollination, etc. has been developed for improving cone yields. Furthermore, several flowering-related genes (FT, Flowering locus T and MADS-box, MCMI, AGAMOUS, DEFICIENCES and SRF) that play a crucial role in flowering in coniferous trees were identified. The results of this study can be useful for forest managers and for enhancing seed yields in conifer plantations for commercial use.

Recent increases in temperature over the semi-arid western United States have been shown to exacerbate drought, reducing streamflow, and increasing stress on ecosystems. Our understanding of the role temperature played during drought in the more distant past is far from complete. While numerous tree-ring proxy records of moisture provide evidence for past extreme droughts in this region, few contemporaneous tree-ring proxy records of temperatures exist. This limits our ability to evaluate the variable influence of temperature on drought over past centuries and to contextualize the present interplay of moisture and temperature during more recent drought events. It is also important to understand the complexity of climatic interactions that produced drought under natural variability prior to evaluating the potential impacts of future climate change. In response to this knowledge gap, we undertook the first extensive evaluation of climate sensitivity in Rocky Mountain bristlecone pine (Pinus aristata Engelm.), focusing on the potential for developing new multi-century proxy records of both temperature and precipitation. We isolated dominant patterns of growth variability among trees from ten ring-width datasets across the Southern Rocky Mountains of Colorado and New Mexico and assessed their response to climate. We utilized both an empirical orthogonal function (EOF) analysis and a modified form of hierarchical cluster analysis to produce time series representing growth patterns in P. aristata. The results indicate a widespread June drought stress signal with a high potential for multi-millennial reconstruction. We also found a positive minimum temperature response during late summer, evident only at lower frequency and co-occurring at locations with the June drought stress signal. The potential for temperature reconstruction will require further investigation into the physiological linkages between P. aristata and climate variability. The presence of multiple climate responses within P. aristata sampling sites highlights the need for particular care when including P. aristata in regional climate reconstructions.

The long-lived five-needle pines, Pinus flexilis (limber pine) and Pinus longaeva (Great Basin bristlecone pine) can co-occur and may form symbiotic partnerships with the same species of ectomycorrhizal fungi. These shared symbiotic relationships may facilitate the persistence of these pine species. Throughout their lives, P. flexilis and P. longaeva may also assemble unique belowground fungal communities, adding to the conservation value of ancient trees. We used MiSeq sequencing of fungal rDNA to compare fungal community similarity for co-occurring P. flexilis and P. longaeva roots and soils in an old-growth forest at the Utah Forest Dynamics Plot, Utah, USA. We cored trees to measure their age and determine whether fungal communities change with advanced tree age. We found 720 amplicon sequence variants associated with P. flexilis roots, 736 with P. longaeva roots, and 199 that were shared between the two pines. Root-associated fungal communities were significantly different between P. flexilis and P. longaeva despite similar soil communities. The fungal community composition on P. flexilis roots and around P. longaeva soil was associated with advanced tree age up to 1340 years. The root-associated fungal community of P. flexilis and the soil community of P. longaeva increased in dissimilarity with tree age, indicating that age heterogeneity within old-growth stands promotes fungal diversity. The significant differences in root-associated fungal communities between the two pine species highlights that they are likely engaged in different bi-directional selection with fungal communities.

As a result of climatic warming, tree species ranges are generally expected to move upslope in elevation. Although this upward range migration is likely determined principally by temperature, other factors such as habitat and soil moisture availability contribute to a species’ ability to establish in new areas. Throughout the montane ecosystems of the western US, effective drying is predicted, resulting from increasing temperatures and potentially reduced precipitation. The tree species that can better establish in these future high-elevation forests will likely expand their ranges while potentially excluding other species. Using a greenhouse experiment, we compared the response of limber pine and Great Basin bristlecone pine, the two dominant Great Basin sub-alpine species, to various levels of drought at different stages during their establishment. We found that during the first year of establishment, limber pine had greater diameter growth but lower height growth than bristlecone pine, while during the second year of establishment, limber pine had greater diameter and height growth rates across all treatments. During the post-germination period and in the second year of establishment, bristlecone pine seedlings had a higher survival rate than limber pine. During the first year of establishment there was no determinable difference in survival between the species. Limber pine displayed earlier mortality and lower survival under nearly all treatments across both first-and second-year periods. In general, an increase in drought severity corresponded to an overall earlier mortality onset as well as decreased survival in both species. However, in the first year of establishment under the no water treatment, both species showed later mortality than all other treatments, even having longer survival durations than a treatment with slightly more water. Limber pine seedlings effectively grew at higher rates than bristlecone pine seedlings, while dying younger. The different response of each species to drought stress during the establishment phase suggests an asymmetric competition under two possible climate change scenarios: a warmer, wetter future may favor limber pine, while a warmer, drier future may favor GB bristlecone pine. For the Great Basin’s sub-alpine forest community, this foreshadows a more complex future change in tree demographics than simple upslope migration.

Over the last two decades, mountain pine beetle ( Dendroctonus ponderosae ) populations reached epidemic levels across much of western North America, including high elevations where cool temperatures previously limited mountain pine beetle persistence. Many high-elevation pine species are susceptible hosts and experienced high levels of mortality in recent outbreaks, but co-occurring Great Basin bristlecone pines ( Pinus longaeva ) were not attacked. Using no-choice attack box experiments, we compared Great Basin bristlecone pine resistance to mountain pine beetle with that of limber pine ( P. flexilis ), a well-documented mountain pine beetle host. We confined sets of mountain pine beetles onto 36 pairs of living Great Basin bristlecone and limber pines and recorded beetle status after 48 h. To test the role of induced defenses in Great Basin bristlecone pine resistance, we then repeated the tests on 20 paired sections of Great Basin bristlecone and limber pines that had been recently cut, thereby removing their capacity for induced defensive reactions to an attack. In tests on cut trees, we also investigated the potential for population-level differences in mountain pine beetle host selection behavior by testing beetles from two separate geographic regions. Beetles placed on Great Basin bristlecone pine rarely initiated attacks relative to those placed on limber pine in both studies, regardless of the beetle population source. Our results indicate that Great Basin bristlecone pine has a high level of resistance to mountain pine beetle due at least in part to stimuli that repel pioneering attackers from initiating attacks, even when induced defenses are compromised.

In response to climate warming, subalpine treelines are expected to move up in elevation since treelines are generally controlled by growing season temperature. Where treeline is advancing, dispersal differences and early life stage environmental tolerances are likely to affect how species expand their ranges. Species with an establishment advantage will colonize newly available habitat first, potentially excluding species that have slower establishment rates. Using a network of plots across five mountain ranges, we described patterns of upslope elevational range shift for the two dominant Great Basin subalpine species, limber pine and Great Basin bristlecone pine. We found that the Great Basin treeline for these species is expanding upslope with a mean vertical elevation shift of 19.1 m since 1950, which is lower than what we might expect based on temperature increases alone. The largest advances were on limber pine-dominated granitic soils, on west aspects, and at lower latitudes. Bristlecone pine juveniles establishing above treeline share some environmental associations with bristlecone adults. Limber pine above-treeline juveniles, in contrast, are prevalent across environmental conditions and share few environmental associations with limber pine adults. Strikingly, limber pine is establishing above treeline throughout the region without regard to site characteristic such as soil type, slope, aspect, or soil texture. Although limber pine is often rare at treeline where it coexists with bristlecone pine, limber pine juveniles dominate above treeline even on calcareous soils that are core bristlecone pine habitat. Limber pine is successfully "leap-frogging" over bristlecone pine, probably because of its strong dispersal advantage and broader tolerances for establishment. This early-stage dominance indicates the potential for the species composition of treeline to change in response to climate change. More broadly, it shows how species differences in dispersal and establishment may result in future communities with very different specific composition.

Little is known about fuel characteristics and dynamics in GBBP communities, and current monitoring programs inadequately quantify the surface and canopy fuels of this system. Using the Forest Inventory Analysis (FIA) plot variables of tree species, height, diameter at breast height (DBH), canopy base height (CBH), coarse (CWD) and fine (FWD) woody debris counts, and canopy fuels measurements, this paper examines the effects of climate-induced changes to fuel loading, fire hazard and risk on predicted changes in fire behavior and severity. Field transects were installed using FIA protocols along environmental gradients. Plots were located every 22 chains or ∼440 m along random transects on Mt. Washington in the Great Basin National Park (GBNP) and in the nearby Mt. Moriah Wilderness, NV. Additional plots were installed at Notch Peak (UT), Cave Mountain (NV), and Wheeler Peak (GBNP, NV). Linear regression showed that all classes of FWD decreased with elevation, and only 1000-h fuels remained constant across elevational transects. This, combined with lower CBH and foliar moisture and increasing temperatures due to climate change, increases fire potential at the Great Basin bristlecone pine treeline, threatening the oldest individuals of this iconic species. New information about discontinuous fuels will aid in management of high elevation alpine treeline forests.

In this paper, we provide the first documented evidence of Pinus longaeva from the Tushar Mountain range in central Utah. The P. longaeva trees, initially noticed at the end of September, and further surveyed during the first week of October 2016 are present on 6 small sites on the north-facing slopes of the North Fork of North Creek in the Tushar Mountains of the Fishlake National Forest. We estimate that there are currently up to 179 live individuals that range in age from seedlings to approximately 1400 years. Our data indicate these are particularly slow-growing specimens on very steep sites, in soil of igneous origin. Though many of the trees are infested with dwarf mistletoe, there is little indication that the population is currently at risk from fire, bark beetle attack, or many other common pathogens characteristic of other Pinus species. Nonetheless, there may be reasons for concern associated with future changes to the climate of southern Utah, as well as the impact of invasive specie...

Tree species are highly vulnerable to anthropogenic environmental change, and are increasingly being challenged by non-native pests and climate change. Rocky Mountain bristlecone pines are long-lived, exhibit delayed maturation, have low genetic diversity, and inhabit cold, high-elevation environments. They are threatened by the non-native disease white pine blister rust, warming temperatures, changing precipitation patterns, and altered disturbance regimes. The goal of this work was to (1) sample the range-wide genetic diversity of bristlecone pine for ex situ seed and tissue collections and research before the populations are impacted, (2) assess the health and ecological conditions of the species across its geographic range (61 stands) to provide a baseline by which to evaluate future changes, and (3) assess relationships between stand and regeneration characteristics and topographic, geographic, and climatic factors to identify vulnerabilities and proactive management interventions to increase population resilience. Local variation in topoclimate was strongly related to stand structure, composition, health, and regeneration. Bristlecone pine currently showed only minor impacts from insects and pathogens, but relationships between cone production and regeneration with climate variables suggest vulnerabilities to projected climate change. Both cone production and seedling regeneration were also linked to stand structure and ground cover that provide opportunities for proactive in situ management to increase population size to mitigate potential future climate- and pathogen-driven declines. These efforts represent the first proactive coordinated range-wide genetic collection design and forest health assessment for a threatened, but not yet impacted, tree species and offers a model for other species at risk.

This paper documents a pilot study investigating the potential use of pinyon pine (Pinus monophylla Torr. & Frem) growing in the White Mountains of eastern California for climate reconstructions. The single-leaf pinyon pine from this study exhibit a significant and stable relationship with annual (August–July) precipitation over the instrumental record (r = 0.69). This relationship is stronger than that of the lower forest border bristlecone pine (Pinus longaeva) growing nearby. Spatially, the climate-growth relationship remains strong beyond this localized region, extending over Southern California. Although pinyon pine is not as long lived as the bristlecone pine, these results indicate that the strength of the climate-growth relationship makes this species valuable in developing climate reconstructions in the future. Additionally, the presence of persistent remnant wood at all sampling sites offers an opportunity to extend pinyon records further back in time. Furthermore, the close proximity o...

Alpine treeline species, like Great Basin bristlecone pine (GBBP) (Pinus longaeva Bailey), have received attention for their potential as indicators of climate change. Most studies have focused on climate-induced changes to treeline position, but climate effects on the physiology and stress of treeline plants remain poorly understood. Volatile organic compounds (VOCs) could provide insights into plant responses to climate change since the quantity and blends of VOCs released by plants exhibit variation in response to the environment, and can convey detailed information about the status of the emitting plant. We collected and analyzed GBBP VOCs and within-needle chemistry along elevational gradients (lower treeline, upper treeline, and midway in between) near the northern and southern geographic limits of GBBP. Random Forest analysis distinguished elevation classes using VOCs with 83% accuracy and identified the compounds most important for classification. Ordination revealed that elevation, temperature, heat load index, and relative humidity were significantly correlated with VOCs. Within-needle chemistry provided less predictive value in classifying elevation class (73% accuracy) and was correlated only with elevation and heat load index. These findings suggest that GBBP VOCs are highly sensitive to the environment and could be used to assess and predict tree status and responses to environmental change. The potential effects of climate- and elevation-induced changes in GBBP chemistry on abiotic and biotic interactions are discussed.

Frost rings can provide direct evidence of anomalously cold summertime conditions on hemispheric scales. Here we report frost rings in subfossil pinewood from Finnish Lapland dated dendrochronologically to AD 536 and 1627 BC. These exact calendar dates have been vividly discussed in the literature in the respective contexts of a cold climate anomaly/dust veil/crop failure/famine/Justinianic Plague and the Minoan eruption of Thera (Santorini). Coinciding anomalies in growth and carbon isotope ratios (delta C-13) indicate cold and overcast conditions in these years in Finnish Lapland, typical to conditions induced by volcanic dust veils. This evidence reinforces the view of multiple climatic drivers strongly effecting contemporary societies around AD 536 and provides important new evidence regarding the 1627 BC event. We report a frost ring for this year, and also consider evidence from Lapland for other Thera candidate eruptions in the 16th century BC. The marker years 1560 BC and 1546 BC in bristlecone pine tree rings in North America are positioned within negative departures in our delta C-13 data. Most likely, the frosts occurred somewhere in July and were driven by dust veils from Northern Hemisphere. Although not indicative of volcanic provenance, frost rings and other dendroclimatic proxies dated to exact calendar years offer important time markers for chronological frameworks which can synchronize archaeological, historical and environmental data to further our understanding of environmental changes at scales that matter to human societies. (C) 2018 Elsevier Ltd. All rights reserved.

Two radiocarbon excursions (AD 774–775 and AD 993–994) occurred due to an increase of incoming cosmic rays on a short timescale. The most plausible cause of these events is considered to be extreme solar proton events (SPE). It is possible that there are other annual 14C excursions in the past that have yet to be confirmed. In order to detect more of these events, we measured the 14C contents in bristlecone pine tree-ring samples during the periods when the rate of 14C increase in the IntCal data is large. We analyzed four periods every other year (2479–2455 BC, 4055–4031 BC, 4465–4441 BC, and 4689–4681 BC), and found no anomalous 14C excursions during these periods. This study confirms that it is important to do continuous measurements to find annual cosmic-ray events at other locations in the tree-ring record.

We investigated the interaction between soil water supply and atmospheric evaporative demand for driving the seasonal pattern of transpiration in sky-island high-elevation forest ecosystems. Sap flow measurements were collected at 10-minute intervals for five consecutive years (2013-2017) on two co-occurring subalpine conifers, i.e. limber pine (Pinus flexilis) and bristlecone pine (Pinus longaeva). Our study site is part of the Nevada Climate-ecohydrological Assessment Network (NevCAN), and is located at 3355 m a.s.l. within an undisturbed mixed-conifer stand. We found that seasonal changes in soil moisture regulated transpiration sensitivity to atmospheric conditions. Sap flow density was mainly limited by evaporative demands under non-water limiting conditions, but was influenced only by soil moisture when water availability decreased. Daily sap flow density increased with radiation and soil moisture in June and July when soil moisture was generally above 10%, but correlated only with soil moisture in August and September when soil drought occurred. Sap flow sensitivity to vapor pressure deficit and solar radiation was therefore reduced under decreasing soil moisture conditions. Transpiration peaked in mid-to-late June during both dry and wet years, with a lower peak in late summer during wet years. Normalized mean daily canopy conductance of both species declined with decreasing soil moisture (i.e., increasing soil drought). Severe soil drying (i.e., soil moisture7% at 20 cm depth), which was rarely detected in wet summers (2013-2014) but occurred more frequently in dry summers (2015-2017), induced a minimum in crown conductance with unchanged low-level sap flow, which might potentially trigger hydraulic failure. The minimum sap flow level under severe soil drought was higher for limber pine than bristlecone pine, possibly because of wider tracheids in limber compared to bristlecone pine. Our findings provide insights into physiological mechanisms of drought-induced stress for iconic sky-island five-needle pines located at high elevation in xeric environments.

The study of anatomical irregularities in tree rings has recently gained momentum as a complement to traditional tree-ring measurements as they may provide information on extreme climatic events. Two anomalies, blue rings (BR) and frost rings (FR), were analyzed in bristlecone pine (Pinus longaeva D.K. Bailey) trees located along an elevation gradient in northeastern Nevada. These two subannual ring anomalies were systematically compiled for two periods; one centered on 536 CE (well-known for a volcanically-induced period of climatic cooling) and the other on 1965 CE (useful due to the availability of instrumental climate data). During the period 523–545 CE (n ≥ 10 trees), both BR and latewood FR (LWFR) were recorded abundantly in 532 and 536, as well as a BR cluster from 539 to 542 CE. Years when trees solely recorded a BR (without an accompanying LWFR) were more frequent in the earlier period than in the modern period (1954–2006 CE; n ≥ 10 trees) when both anomalies tended to co-occur. These results suggest a shorter growing season in the 536 period than in the 20th century. Modern BR/LWFR were most abundant in 1965 and 1978 CE. Both anomalies were mainly observed in the highest elevation trees and both were produced in years characterized by cooler than average temperatures throughout the growing season. Anatomically, BR and LWFR did not differ significantly in tracheid dimensions except that LWFR clearly showed damages associated with sub-freezing temperatures. The main feature distinguishing BR and LWFR from “normal” tree rings was a significant reduction in latewood secondary wall thickness. In P. longaeva, BR like pale latewood (light) rings, result from short and cool growing seasons which leads to reduced (or interrupted) lignification of tracheids. In species producing extremely narrow latewood like P. longaeva it may be difficult to macroscopically identify pale latewood years, thus rendering microscopic investigation of BR as a climate proxy useful in paleoclimatic research.

Like many other high elevation alpine tree species, Rocky Mountain bristlecone pine (Pinus aristata Engelm.) may be particularly vulnerable to climate change. To evaluate its potential vulnerability to shifts in climate, we defined the suitable climate space for each of four genetic lineages of bristlecone pine and for other subalpine tree species in close proximity to bristlecone pine forests. Measuring changes in the suitable climate space for lineage groups is an important step beyond models that assume species are genetically homogenous. The suitable climate space for bristlecone pine in the year 2090 is projected to decline by 74% and the proportional distribution of suitable climate space for genetic lineages shifts toward those associated with warmer and wetter conditions. The 2090 climate space for bristlecone pine exhibits a bimodal distribution along an elevation gradient, presumably due to the persistence of the climate space in the Southern Rocky Mountains and exclusion at mid-elevations by conditions that favor the climate space of other species. These shifts have implications for changes in fire regimes, vulnerability to pest and pathogens, and altered carbon dynamics across the southern Rockies, which may reduce the likelihood of bristlecone pine trees achieving exceptional longevity in the future. The persistence and expansion of climate space for southern bristlecone pine genetic lineage groups in 2090 suggests that these sources may be the least vulnerable in the future. While these lineages may be more likely to persist and therefore present opportunities for proactive management (e.g., assisted migration) to maintain subalpine forest ecosystem services in a warmer world, our findings also imply heighted conservation concern for vulnerable northern lineages facing range contractions.

Over the period 1883–2013, recruitment of subalpine limber pine (Pinus flexilis E. James) and Great Basin bristlecone pine (Pinus longaeva D.K. Bailey) above the upper tree line, below the lower tree line, and across middle-elevation forest borders occurred at localized sites across four mountain ranges in the western Great Basin. A synchronous pulse at all ecotones occurred between 1963 and 2000 (limber pine) and between 1955 and 1978 (bristlecone pine) when pines expanded 225 m beyond forest borders. Little recruitment occurred before this interval or in the 21st century. No obvious environmental factors distinguished recruitment locations from nonrecruitment locations. Where their ranges overlap, limber pine has leapfrogged above bristlecone pine by 300 m. Limber pine tree-ring chronologies, developed to compare radial-growth responses with recruitment, showed dominant pulses of increased growth during the same interval as recruitment. Significant climate correlations of growth and recruitment indicated lead and lag effects as much as 6 years and complex relationships with climate variables, corroborating the importance of cumulative climate effects relative to any single year. Water relations were the most important drivers of growth and recruitment and interacted with growing-season minimum and maximum temperatures. These results underscore the importance of studying ecotones at all margins when evaluating conifer response to climate change.

Using a combination of 23 radiocarbon ages and annual ring counts from 18 Rocky Mountain bristlecone pine ( Pinus aristata) remnants above the local present-day limits, a period of higher treeline has been determined for two sites near the Continental Divide in central Colorado. The highest remnants were found about 30 m above live bristlecone pines of similar size. The majority of the remnants, consisting of standing snags, large logs, and smaller remains, are highly eroded, such that the innermost annual rings of all but one are missing. The radiocarbon ages obtained from the oldest wood recovered from each remnant indicate that the majority were established above the present-day limit of bristlecone pine from prior to 2700 cal. yr BP to no later than about 1200 cal. yr BP. These radiocarbon ages combined with the annual ring count from the corresponding remnant indicate that the majority of the sampled remnants grew above the present-day limit of bristlecone pine from sometime before 2700 cal. yr BP to about 800 cal. yr BP. Evidence of recent climatic warming is demonstrated at one of the sites by young bristlecone pine saplings growing next to the highest remnants; the saplings were established after AD 1965 and represent the highest advance of treeline in at least 1200 years.

Microsites created by live plants and non-living structures can be important for plant establishment where abiotic stress is high. The activity of herbivores and resulting pattern of seedling survival also affects plant distributions. We investigated factors thought to influence survival of bristlecone pine (Pinus longaeva Bailey) seedlings in the White Mountains, California, USA, with two field experiments in which microsite and exposure to herbivory were manipulated. In the microsite experiment, we planted seedlings underneath wooden shade structures, underneath sagebrush plants, and in exposed locations. In the herbivory experiment, we tested the effects of herbivore exclusion in three different habitat types. We planted seedlings in full wire cages (herbivores excluded), in half cages (herbivores allowed while enabling assessment of possible non-herbivore effects of cages on seedling survival), or with no cage (herbivores allowed), and repeated these treatments in three habitats: below, within, and above a bristlecone woodland. Over three growing seasons, seedlings planted under wooden shade structures had higher survival (28.9%) than seedlings growing under sagebrush (10%) or in exposed areas (3.3%). We found a significant treatment by habitat interaction in the herbivory experiment (χ2 = 12.056, P = 0.017), driven by a clear pattern of high herbivory inside the bristlecone woodland, but not above or below it. Our results suggest that biologically-derived microsites (shelter from dead wood and live shrubs), as well as herbivore-mediated density-dependent mortality, are important determinants of bristlecone pine seedling survival.

Article, The largest global source of volatile organic compounds (VOCs) in the atmosphere is from biogenic emissions. Plant stressors associated with a changing environment can alter both the quantity and composition of the compounds that are emitted. This study investigated the effects of one global change stressor, increased herbivory, on plant emissions from five different coniferous species: bristlecone pine (Pinus aristata), blue spruce (Picea pungens), western redcedar (Thuja plicata), grand fir (Abies grandis), and Douglas-fir (Pseudotsuga menziesii). Herbivory was simulated in the laboratory via exogenous application of methyl jasmonate (MeJA), a herbivory proxy. Gas-phase species were measured continuously with a gas chromatograph coupled to a mass spectrometer and flame ionization detector (GC–MS–FID). Stress responses varied between the different plant types and even between experiments using the same set of saplings. The compounds most frequently impacted by the stress treatment were alpha-pinene, beta-pinene, 1,8-cineol, beta-myrcene, terpinolene, limonene, and the cymene isomers. Individual compounds within a single experiment often exhibited a different response to the treatment from one another., published version, http://purl.org/eprint/status/PeerReviewed

This collaboration of ink drawings and texts examines the high altitude landscape and forests of the White Mountains, in Eastern California, in particular the bristlecone pine, and a neighboring species, the limber pine and western juniper, and their environs. It is the premise of the writer and artist that drawing and writing about these species and this place fosters a valuable kind of local knowledge, while producing striking works of art and craft.

Natural variations and responses to climate change can be identified within climatically sensitive ecosystems by monitoring growing season events. In 1962–1964, Fritts conducted a phenologic study on Pinus longaeva in the White Mountains of California. He monitored growing season events, environmental data, and dendrometer readings. In this study morphological and physiological phenophases, dendrometer traces, and environmental data were collected throughout the summers of 2007 and 2008 in the White Mountains of California to better understand variability in Pinus longaeva phenology and identify any shifts in the growing season since the 1962–1964 study (Fritts 1969). As a result of a late-season snow storm, observable phenophases in 2008 were 12 days later than in 2007. Pollination onset was slightly earlier than in the 1962–1964, which may indicate that accumulated heat or a combination of environmental factors influence these phenophases. Duration and timing of cambial activity in the present ...

Radiocarbon content in tree rings can be an excellent proxy of the past incoming cosmic ray intensities to Earth. Although such past cosmic ray variations have been studied by measurements of 14C contents in tree rings with ≥10-y time resolution for the Holocene, there are few annual 14C data. There is a little understanding about annual 14C variations in the past, with the exception of a few periods including the AD 774−775 14C excursion where annual measurements have been performed. Here, we report the result of 14C measurements using the bristlecone pine tree rings for the period from 5490 BC to 5411 BC with 1- to 2-y resolution, and a finding of an extraordinarily large 14C increase (20‰) from 5481 BC to 5471 BC (the 5480 BC event). The 14C increase rate of this event is much larger than that of the normal grand solar minima. We propose the possible causes of this event are an unknown phase of grand solar minimum, or a combination of successive solar proton events and a normal grand solar minimum.

The correlation of the distribution of five subalpine and montane tree species with precipitation and temperature were modeled using GIS. The results were compared with data presented by Thompson et al. (2000). Distributions of subalpine fir (Abies concolor), Engelmann spruce (Picea engelmannii), lodgepole pine (Pinus contorta), limber pine (Pinus flexilis) and bristlecone pine (Pinus aristata) were compared to estimated precipitation and temperature fields that had been constructed from the Parameter-elevation Regressions on Independent Slopes Model (PRISM), National Climatic Data Center (NCDC) station data, and Snowpack Telemetry (SNOTEL) system data. Plant distribution maps from Little (1971) and CoGAP (2001) were used to determine the temperature and precipitation associated with the selected tree species. The estimates from this study were compared to those of Thompson, Anderson & Bartlein (2000). In many cases precipitation and temperatures values were higher than those of Thompson, Anderson & Bartlein (2000). Suggestions are made to improve the predictive power of GIS analysis for mapping climate and plant variability.

A 1343-year tree-ring chronology was developed from Qilian junipers in the central Qilian Mountains of the northeastern Tibetan Plateau (TP), China. The climatic implications of this chronology were investigated using simple correlation, partial correlation and response function analyses. The chronology was significantly positively correlated with temperature variables prior to and during the growing season, especially with monthly minimum temperature. Minimum temperature anomalies from January to August since AD 670 were then reconstructed based on the tree-ring chronology. The reconstruction explained 58% of the variance in the instrumental temperature records during the calibration period (1960–2012) and captured the variation patterns in minimum temperature at the annual to centennial timescales over the past millennium. The most recent 50 years were the warmest period, while 1690–1880 was the coldest period since AD 670. Comparisons with other temperature series from neighbouring regions and for the Northern Hemisphere as a whole supported the validity of our reconstruction and suggested that it provided a good regional representation of temperature change in the northeastern Tibetan Plateau. The results of wavelet analysis showed the occurrence of significant quasi-periodic patterns at a number of recurring periods (2–4, 40–50, and 90–170 years), which were consistent with those associated with El Niño–Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO) and solar activity. The comparison between the reconstructed temperature and the index of tropical volcanic radiative forcing indicated that some cold events recorded by tree rings may be due to the impact of tropical volcanic eruptions.

The calibration of radiocarbon dates by means of a master calibration curve has been invaluable to Earth, environmental and archeological sciences, but the fundamental reason for calibration is that atmospheric radiocarbon content varies because of changes in upper atmosphere production and global carbon cycling. Improved instrumentation has contributed to high-resolution (interannual) radiocarbon activity measurements, which have revealed sudden and anomalous activity shifts previously not observed at the common resolution of 5–10 years of most of the calibration scale. One such spike has been recently reported from tree rings from Japan and then again in Europe at A.D. 774–775, for which we report here our efforts to both replicate its existence and determine its spatial extent using tree rings from larch at high latitude (northern Siberia) and bristlecone pine from lower latitude (the White Mountains of California). Our results confirm an abrupt ~ 15‰ 14C activity increase from A.D. 774 to 776, the size and now the hemispheric extent of which suggest that an extraterrestrial influence on radiocarbon production is most likely responsible.

Lake-level changes since ca. 3.6 kilo-annum (ka) at Emerald Lake in the Upper Arkansas River Basin of west-central Colorado coincide in time with changes of the opposite direction at Lake of the Woods in northwestern Wyoming. The contrast provides evidence of a multi-centennial moisture dipole across the Southern and Central Rocky Mountains' region similar to one associated with the effects of the El Nino Southern Oscillation (ENSO) on annual to decadal time scales today. Cores and ground penetrating radar (GPR) profiles from Emerald Lake show that deep-water muds accumulated as extensively across the lake basin as today at ca. 3.6–3.0 and 1.4–0.8 ka, and nearly as extensively at 2.5–1.9 ka. The extensive muds indicate episodes of high water at Emerald Lake and date to times when Lake of the Woods was low. Nearshore sand layers at Emerald Lake indicate that water levels fell during the intervening centuries, including when bristlecone pine chronologies have documented repeated multi-decadal droughts in the Upper Arkansas River Basin. Water levels were also low, based on the absence of nearshore mud accumulation, before ca. 3.6 ka, and dramatically lower (>2 m in the currently 4.5-m deep lake) before a sharp rise in water levels by ca. 5.7 ka. A basin-wide change in sediment accumulation patterns, consistent with an expansion and deepening of the lake at ca. 5.7 ka, correlates with regional cooling and similar evidence of increased effective moisture at Lake of the Woods and other sites throughout central North America. The step increase in moisture availability may relate to a global-scale reorganization of climatic patterns, which developed as the mid- and high-latitudes cooled in response to a decline in summer insolation.

Mountain conifers in the Great Basin of North America have provided some of the longest, continuous, and annually resolved paleoclimate records. Climate-growth relationships at the cellular level, which help understand wood formation processes that underlie dendroclimatic reconstructions, are at present largely unexplored in the Great Basin. We analyzed 42 trees located in the Snake Range (eastern Nevada, USA) at three sites along an elevation gradient. Sampled species included white fir (Abies concolor), Douglas fir (Pseudotsuga menziesii), limber pine (Pinus flexilis), bristlecone pine (Pinus longaeva), and Engelmann spruce (Picea engelmannii). Wood anatomical features were quantified for two consecutive years, 2011 and 2012. Lumen area, cell wall thickness, lumen diameter, and wall-to-cell ratio were measured for the total ring as well as for earlywood and latewood. Mean standardized tracheidograms highlighted differences between 2011 and 2012, in particular concerning lumen area and wall-to-cell ratio. Most annual variation was due to earlywood, rather than latewood. Anatomical parameters of limber pine, the only species that could be tested at both the montane and subalpine sites, varied with elevation. Principal component analysis showed that the main axis of variability was related to dimensional parameters (e.g. lumen area), which reflected differences in water availability.

The meteorological factors involved in the formation of earlywood frost rings in Rocky Mountain bristlecone pine (Pinus aristata) have not been described in detail. This study used 51 tree-ring dated Rocky Mountain bristlecone pine trees growing at ca. 3500 m a.s.l. on Mt. Goliath, Colorado, to develop earlywood and latewood frost ring chronologies dating from 1930 to 2010 for investigation of the regional and large-scale weather anomalies responsible for these unusual growing season freeze events. The high-elevation meteorological station at Niwot Ridge, Colorado, was used to document the daily temperature anomalies most likely associated with these frost-damaged rings. NCEP-NCAR Reanalysis data were used to examine the synoptic meteorological conditions that tend to prevail during these unusual growing season temperature conditions. Earlywood frost rings occur during anomalous late-May and June freeze events in the Colorado Rockies associated with unseasonal mid-latitude circulation, including the penetration of a deep upper-level low pressure system and cold surface air temperatures into the west-central United States. The three latewood frost rings all occurred during September freeze events also associated with unseasonal and highly amplified mid-latitude circulation. The chronology of these early and late growing season freeze events may provide a useful independent check on daily temperature minima estimated with reanalysis techniques, and they can be extended into the pre-instrumental era thanks to the great age of Rocky Mountain bristlecone pine. Frost damage in Mt. Goliath bristlecone pine appears to be most frequent and severe in young trees found in the depressed tree line below a large cirque subject to intense cold air drainage. The development of the most detailed tree-ring records of past freeze events may therefore benefit from site selection in these cold air drainages, along with age-stratified tree sampling to ensure that the young and most frost susceptible age classes are well represented throughout the chronology.

Two floating, ring-width chronologies predate the long bristlecone pine (Pinus longaeva) absolutely-dated, ring-width chronology from the Methuselah Walk (MWK) site in the White Mountains of California. The two non-overlapping floating chronologies were derived from samples that crossdate internally but are temporally unconnected to each other and to the nearly 9000-year, ring-width sequence that is crossdated to the calendar year. We used radiocarbon wiggle-matching and crossdating to place the two floating sequences more accurately in time and to better understand the temporal relationships between the three time series. The trees from the oldest floating sequence were alive near the beginning of the Pleistocene/Holocene boundary and they do not overlap with the other chronologies because of a gap of two-to-three centuries between the two floating series. However, the trees from the younger floating sequence likely do overlap with the long, calendar-dated MWK chronology. We find a possible 57-year overlap that connects these two. If confirmed with additional work, the resulting tree-ring dated annual record from this single location will span 10,359 years, a unique accomplishment in dendrochronology.

Biogenic volatile organic compound (BVOC) emissions from six coniferous tree species, i.e. Pinus ponderosa (Ponderosa Pine), Picea pungens (Blue Spruce), Pseudotsuga menziesii (Rocky Mountain Douglas Fir) and Pinus longaeva (Bristlecone Pine), as well as from two deciduous species, Quercus gambelii (Gamble Oak) and Betula occidentalis (Western River Birch) were studied over a full annual growing cycle. Monoterpene (MT) and sesquiterpene (SQT) emissions rates were quantified in a total of 1236 individual branch enclosure samples. MT dominated coniferous emissions, producing greater than 95% of BVOC emissions. MT and SQT demonstrated short-term emission dependence with temperature. Two oxygenated MT, 1,8-cineol and piperitone, were both light and temperature dependent. Basal emission rates (BER, normalized to 1000μmolm(-2)s(-1) and 30°C) were generally higher in spring and summer than in winter; MT seasonal BER from the coniferous trees maximized between 1.5 and 6.0μgg(-1)h(-1), while seasonal lows were near 0.1μgg(-1)h(-1). The fractional contribution of individual MT to total emissions was found to fluctuate with season. SQT BER measured from the coniferous trees ranged from

The instrumental temperature record is of insufficient length to fully express the natural variability of past temperature. High elevation tree-ring widths from Great Basin bristlecone pine (Pinus longaeva) are a par- ticularly useful proxy to infer temperatures prior to the instrumental record in that the tree-rings are annually dated and extend for millennia. From ring-width measurements integrated with past treeline elevation data we infer dec- adal- to millennial-scale temperature variability over the past 4,500 years for the Great Basin, USA. We find that twentieth century treeline advances are greater than in at least 4,000 years. There is also evidence for substantial volcanic forcing of climate in the preindustrial record and considerable covariation between high elevation tree-ring widths and temperature estimates from an atmosphere- ocean general circulation model over much of the last millennium. A long-term temperature decline of *-1.1 C since the mid-Holocene underlies substantial volcanic forcing of climate in the preindustrial record.

Background: Forests in subarctic regions inhabit the transitional zone between the temperate region and the Arctic, where plant survival depends on the capability of individuals to adjust to changing environments. This transitional zone, generally falling between 50° N and 70° N, is becoming increasingly vulnerable under a changing climate, with treelines moving further north and also higher up slopes. Aims: The current study was carried out at 68° N, the most sensitive zone of the subarctic and northern limit of tree growth in Finnish Lapland. The physiology of trees in these conditions is still not fully understood, and an attempt is made here to contribute to a better understanding of the functionality of leaves by studying the spectral characteristics of needles of Pinus sylvestris along an altitudinal transect. Methods: A variety of spectral indices derived from high-resolution reflectance spectra were measured on freshly excised pine needles. The specific hypothesis is that spectral reflectance data...

AMS-based 14 C measurements have been obtained on 53 dendrochronologically-dated Bristlecone pine ( Pinus longaeva ) wood samples in decadal increments spanning 2300–2750 cal BP with particular interest focused on the decades centered on 2405 cal BP and 2625 cal BP. In general, there is overall agreement with the current IntCal04/09 consensus calibration curve for this period. For the 2400–2410 cal BP interval, our Bristlecone-based 14 C value is consistent with the 14 C value obtained by Belfast on Irish oak for that decade but not on German oak values obtained by Seattle. Our 14 C value for the 2620–2630 cal BP interval is consistent with the German oak (Heidelberg)-based 14 C decadal value. The 10 Be-based reconstruction of 14 C variations over the 2620–2630 cal BP interval also supports the Heidelberg data although clearly additional clarifications are required before the current tree ring-based 14 C and ice core-based 10 Be data for this interval can be accurately interpreted and valid inferences obtained.