Western Sites Research Articles

Development and validation of a phenological model for the univoltine European corn borer

AbstractBiological control of a univoltine race of European corn borer, Ostrinia nubilalis Hübner (Lepidoptera: Crambidae), by Trichogramma in Switzerland is currently timed according to repeated, semi‐field observations of the post‐diapause development of the pest at one site. We developed a phenology model with the aims of replacing this costly labour practice and by considering the Swiss landscape. Observations collected over 29 years were used for model calibration and validation. We parameterized a time‐varying distributed delay model based on published laboratory observations of development durations at constant temperatures. The model was driven with hourly temperature recordings beginning on January 1. The calibration of the mean development rates and their variations was based on semi‐field data of larval and pupal development. The model, with its calibrated parameters and their variations, allowed the simulation of mean predictions and prediction intervals. We validated the model predictions of emergence with flight data (obtained via light traps) from several sites in western and northern Switzerland. The simulated mean emergence was 6.9 degree‐days earlier than the observed flight at the calibration sites and only 0.5 degree‐days earlier than the observed flight at other sites. Our simulation of pupation explained half of the variation in emergence time, whereas semi‐field observations of pupation explained three‐quarters of this variation. Our model simulations are not subjected to the local potential biases. Simulation errors from a year with an extremely dry spring were explained by the lack of consideration of humidity by the model. Our simulations provide a valid and less labour‐intensive alternative to observations for timing biological control in the maize‐growing areas of Switzerland and likely other areas of Europe.

Sandals as Icons: Representations in Ancestral Pueblo Rock Art and Effigies in Stone and Wood

Dating the late 1000s to the mid-1200s CE, petroglyphs of sandal images are among others that distinguish ancient Pueblo rock art in the San Juan and Little Colorado River drainages on the Colorado Plateau from Ancestral Pueblo rock art elsewhere across the Southwest. The sandal “track” also has counterparts as effigies in stone and wood often found in ceremonial contexts in Pueblo sites. These representations reflect the sandal styles of the times, both plain in contour and the jog-toed variety, the latter characterized by a projection where the little toe is positioned. These representations are both plain and patterned, as are their material sandal counterparts. Their significance as symbolic icons is their dominant aspect, and a ritual meaning is implicit. As a component of a symbol system that was radically altered after 1300 CE, however, there is no ethnographic information that provides clues as to the sandal icon’s meaning. While there is no significant pattern of its associations with other symbolic content in the petroglyph panels, in some western San Juan sites cases a relationship to the hunt can be inferred. It is suggested that the track itself could refer to a deity, a mythological hero, or the carver ’s social identity. In conclusion, however, no clear meaning of the images themselves is forthcoming, and further research beckons.

Can seed caching enhance seedling survival of Indian ricegrass (Achnatherum hymenoides) through intraspecific facilitation?

Positive interactions among individual plants (facilitation) may often enhance seedling survival in stressful environments. Many granivorous small mammal species cache groups of seeds for future consumption in shallowly buried scatterhoards, and seeds of many plant species germinate and establish aggregated clusters of seedlings from such caches. Scatterhoards made by desert heteromyid rodents provide a major source of seedling recruitment for Indian ricegrass (Achnatherum hymenoides), a perennial bunchgrass species occurring widely across arid southwestern deserts of North America. However, effects of the resulting clumping of seedlings on subsequent survival have not been quantified under field conditions, which include extended periods of excessive summer heat and little precipitation. We monitored Indian ricegrass seedlings transplanted into field exclosures at two western Nevada study sites as either single seedlings or clumps of 25 or 35 seedlings and compared their survival. Survival was positively correlated with the number of seedlings growing together, and survival of whole clumps of 25 or 35 seedlings was significantly greater than that of seedlings growing singly. Moreover, individual seedlings within clumps of 35 seedlings had significantly higher survival than seedlings growing singly. No single seedlings survived through the hot and very dry summer following their planting, but a small proportion (1.8–2.8 %) of individual seedlings within clumps survived. Results of this field experiment suggest that facilitative benefits accruing to Indian ricegrass due to seed-caching desert rodents can extend past seedling establishment and into the long-term survival of the plant.

An aeropalynological survey in the city of Van, a high altitudinal region, East Anatolia-Turkey

Pollen concentrations in the atmosphere of Van city has been monitored for two consecutive years (2010–2011). This was the first detailed aeropalynological study for the elevated East Anatolia Region of Turkey. The sampling was performed by Hirst-type volumetric sampler, and pollen grains of 35 taxa were identified. The main pollen producers of the pollen flora were recorded as: Poaceae (20.94 %), Cupressaceae (10.53 %), Fraxinus (8.56 %), Chenopodiaceae/Amaranthaceae (7.77 %), Populus (7.75 %), Quercus (6.70 %), Platanus (6.68 %), Morus (5.57 %), Plantago (3.03 %). The pollen spectrum reflected the floristic diversity of the region, and the highest pollen concentration was recorded in April. There were a great percentage of allergenic taxa found in the city atmosphere, otherwise many of them scored under threshold values for risk of pollinosis. Statistical analyses were performed for correlating daily pollen concentrations of dominated pollen types concurrent with the data of meteorological parameters in MPS periods and number of significant correlations found. In addition, comparing 2-year data in terms of pollen concentrations and meteorological factors in MPS durations, many variables were found explanatory and concordant with the data. MPS starting dates of many plant taxa were found nearly a month later compared with western sites and lower altitudes of the country as well as Mediterranean countries; this case is mostly thought the ecological factors of the study area which directly affects the plant growth about the timing.

Harmonious communitarianism or a rational public sphere: a content analysis of the differences between comments on news stories on Weibo and Facebook

ABSTRACTIn studying online political communication in China, many researchers apply theories generated in the West (particularly that of the public sphere) without questioning their applicability in the Chinese context. Others argue that new theories must be generated from the ground up, often basing these theories on traditional Chinese philosophies. However, the applicability of these approaches remains unproven. This research uses a content analysis to compare comments on news stories on Chinese and Western social media sites. It finds that there is little evidence to support either the use of public sphere theory in China or the use of traditional conceptions of Eastern styles of communication. Chinese netizens were no more subtle or harmonious (if anything, they were more divisive) and were less likely to talk with others, attempt to understand others’ opinions or attempt to work towards consensus or resolution. Based on these findings, I propose that future research should attempt to build more appropriate theories based on an understanding of how political ideas are actually produced, transmitted and received in society, rather than continuing to apply foreign or ancient theoretical frameworks without a critical interrogation of their applicability in their context of application.

An interesting rock from Krapina

Symbolic items are seldom associated with Neandertals and, when they are, many paleoanthropologists consider them to be Neandertal imitations from modern Homo sapiens. At the Croatian site of Krapina dated to MIS 5e or about 130,000 years ago, among many items, a split limestone rock was excavated by Dragutin Gorjanović-Kramberger between 1899-1905. This brownish rock reveals many dark dendritic forms in cross- and longitudinal section. Of more than 1000 lithic items at Krapina, none resemble this specimen and we propose it was collected and not further processed by the Neandertals because of its aesthetic attributes. Along with other examples from sites in western and central Europe and the recent discovery of eight modified white-tailed eagle talons from Krapina, this unique item suggests that Neandertals were capable, on their own, of incorporating symbolic objects into their culture.

An Assessment of How Nurse Practitioners Create Access to Primary Care in Canadian Residential Long-Term Care Settings.

The aim of this paper is to explore the role and activities of nurse practitioners (NPs) working in long-term care (LTC) to understand concepts of access to primary care for residents. Utilizing the "FIT" framework developed by Penchanksy and Thomas, we used a directed content analysis method to analyze data from a pan-Canadian study of NPs in LTC. Individual and focus group interviews were conducted at four sites in western, central and eastern regions of Canada with 143 participants, including NPs, RNs, regulated and unregulated nursing staff, allied health professionals, physicians, administrators and directors and residents and family members. Participants emphasized how the availability and accessibility of the NP had an impact on access to primary and urgent care for residents. Understanding more about how NPs affect access in Canadian LTC will be valuable for nursing practice and healthcare planning and policy and may assist other countries in planning for the introduction of NPs in LTC settings to increase access to primary care.

Geochemistry of PM<sub>10</sub> over Europe during the EMEP intensive measurement periods in summer 2012 and winter 2013

Abstract. The third intensive measurement period (IMP) organised by the European Monitoring and Evaluation Programme (EMEP) under the UNECE CLTRAP took place in summer 2012 and winter 2013, with PM10 filter samples concurrently collected at 20 (16 EMEP) regional background sites across Europe for subsequent analysis of their mineral dust content. All samples were analysed by the same or a comparable methodology. Higher PM10 mineral dust loadings were observed at most sites in summer (0.5–10 µg m−3) compared to winter (0.2–2 µg m−3), with the most elevated concentrations in the southern- and easternmost countries, accounting for 20–40 % of PM10. Saharan dust outbreaks were responsible for the high summer dust loadings at western and central European sites, whereas regional or local sources explained the elevated concentrations observed at eastern sites. The eastern Mediterranean sites experienced elevated levels due to African dust outbreaks during both summer and winter. The mineral dust composition varied more in winter than in summer, with a higher relative contribution of anthropogenic dust during the former period. A relatively high contribution of K from non-mineral and non-sea-salt sources, such as biomass burning, was evident in winter at some of the central and eastern European sites. The spatial distribution of some components and metals reveals the influence of specific anthropogenic sources on a regional scale: shipping emissions (V, Ni, and SO42−) in the Mediterranean region, metallurgy (Cr, Ni, and Mn) in central and eastern Europe, high temperature processes (As, Pb, and SO42−) in eastern countries, and traffic (Cu) at sites affected by emissions from nearby cities.

The characterisation of amber from deposit sites in western and northern Canada

For years, the recovery of amber beads and other objects with amber components from archaeological sites in Canada has raised questions concerning the deposit site sources for this highly traded material. Objects found at one site may have originated elsewhere, thus, the accurate characterisation of amber could aid in establishing trade. In this investigation, 12 distinct amber specimens from 11 deposit sites in Canada were studied in order to determine their subclass and other distinguishing chemical features. The ambers were analysed using Fourier transform infrared spectrometry (FTIR) in combination with pyrolysis-gas chromatography–mass spectrometry (Py-GC–MS), using a thermal separation probe (TSP) to perform the pyrolysis and sample introduction. Analysis of the amber from the 11 deposits in Canada showed that they represent three different classes: Class Ib (based on regular-labdanes), Class Ic and Class Id (both based on enantio-labdanes). Different forms were found within the Class Ib and Ic ambers, based on the presence and absence of self-crosslinking and free succinic acid. The techniques identified polymeric crosslinking in three subclasses. These include self-crosslinking of communol and communic acid moieties in two Class Ib (form 2) ambers, self-crosslinking of ozol and ozic acid moieties in one Class Ic (form 2) amber and succinylation of the Class Id ambers. Other important characteristics were discovered, including the presence of free succinic acid in six Class Ib (form 1) ambers and one Class Ic (form 1) amber, the presence of diagenetic analogues of both dehydroabietic acid and callitrisic acid in all Class Ib (form 1) ambers, and the attachment of non-polymerisable terpenoids to the macromolecular structures of two Class Ib ambers and one Class Id amber. Amber beads recovered from three Thule sites in the Canadian arctic were characterised and compared to the 12 reference specimens. The beads from site TkAu-1 (Ellesmere Island) were found to originate from the local deposit at Lake Hazen. However, beads from the QeJu-1 (Cornwallis Island) and OkRn-1 (Banks Island) sites closely matched amber specimens from the major deposit at Cedar Lake (Manitoba). This may indicate movement of the Cedar Lake amber to the arctic via trade.

Short-term effects of whole-tree harvesting on understory plant species diversity and cover in two Norway spruce sites in southern Norway

ABSTRACTEffects of clear-cut harvesting on ground vegetation plant species diversity and their cover are investigated at two Norway spruce sites in southern Norway, differing in climate and topography. Experimental plots at these two sites were either harvested conventionally (stem-only harvesting) or whole trees including crowns, twigs and branches were removed (whole-tree harvesting), leaving residue piles on the ground for some months. We compare the number of plant species in different groups and their cover sums before and after harvesting, and between the different treatments, using non-parametric statistical tests. An overall loss of ground vegetation biodiversity is induced by harvesting and there is a shift in cover of dominant species, with negative effects for bryophytes and dwarf shrubs and an increase of graminoid cover. Differences between the two harvesting methods at both sites were mainly due to the residue piles assembled during whole-tree harvesting and the physical damage made during the harvesting of residues in these piles. The presence of the residue piles had a clear negative impact on both species numbers and cover. Pile residue harvesting on unfrozen and snow-free soil caused more damage to the forest floor in the steep terrain at the western site compared to the eastern site.

Applicability of the NGA‐West2 Site‐Effects Model for Central and Eastern North America

Abstract We examine the applicability of the Next Generation Attenuation‐West2 (NGA‐West2) site‐effects model (Seyhan and Stewart, 2014), which is a V S 30 ‐based (time‐averaged shear‐wave velocity in the upper 30 m) model, to sites in central and eastern North America (CENA), using the NGA‐East ground‐motion database. We determine residual site terms by comparing the observed CENA ground‐motion amplitudes, adjusted to B/C site condition ( V S 30 =760 m/s) using the western site‐effects model, to the corresponding predicted amplitudes of a CENA ground‐motion prediction equation for B/C site condition (Yenier and Atkinson, 2015). The CENA prediction model used the same western site model to level the database before model development. Thus, residual trends reveal inadequacies of the western site‐effects model when applied to CENA ground motions. Plotting the residual site terms versus their corresponding site fundamental frequencies ( f peak ) reveals significant f peak ‐dependent trends at all frequencies. Average residual site terms for CENA sites, after the western site amplifications have been removed, can be as large as 0.45 in log10 units (2.8 in nonlog units) around f ≈ f peak . Correlating the site terms with western site‐effects predictions reveals that at f V S 30 in a manner that is similar to the way they behave in the NGA‐West2 database. However, at higher frequencies, the correlation of site amplification with V S 30 decreases markedly in CENA. In contrast, the horizontal‐to‐vertical (H/V) component spectral ratio (as obtained from the NGA‐East ground‐motion data) is a good predictor of the observed f peak ‐dependent site terms, suggesting that H/V spectral ratio is a more reliable predictor of site amplification for the recording stations of the NGA‐East database. The results of this study demonstrate the importance of a well‐calibrated regional site‐effects model for CENA and the importance of f peak as a site indicator.

Understanding a migratory species in a changing world: climatic effects and demographic declines in the western monarch revealed by four decades of intensive monitoring.

Migratory animals pose unique challenges for conservation biologists, and we have much to learn about how migratory species respond to drivers of global change. Research has cast doubt on the stability of the eastern monarch butterfly (Danaus plexippus) population in North America, but the western monarchs have not been as intensively examined. Using a Bayesian hierarchical model, sightings of western monarchs over approximately 40years were investigated using summer flight records from ten sites along an elevational transect in Northern California. Multiple weather variables were examined, including local and regional temperature and precipitation. Population trends from the ten focal sites and a subset of western overwintering sites were compared to summer and overwintering data from the eastern migration. Records showed western overwintering grounds and western breeding grounds had negative trends over time, with declines concentrated early in the breeding season, which were potentially more severe than in the eastern population. Temporal variation in the western monarch also appears to be largely independent of (uncorrelated with) the dynamics in the east. For our focal sites, warmer temperatures had positive effects during winter and spring, and precipitation had a positive effect during spring. These climatic associations add to our understanding of biotic-abiotic interactions in a migratory butterfly, but shifting climatic conditions do not explain the overall, long-term, negative population trajectory observed in our data.

Detection and removal of disturbance trends in tree-ring series for dendroclimatology

Nonclimatic disturbance events are an integral element in the history of forests. Although the identification of the occurrence and duration of such events may help to understand environmental history and landscape change, from a dendroclimatic perspective, disturbance can obscure the climate signal in tree rings. However, existing detrending methods are unable to remove disturbance trends without affecting the retention of long-term climate trends. Here, we address this issue by using a novel method for the detection and removal of disturbance events in tree-ring width data to assess their spatiotemporal occurrence in a network of Scots pine (Pinus sylvestris L.) trees from Scotland. Disturbance trends “superimposed” on the tree-ring record are removed before detrending and the climate signals in the precorrection and postcorrection chronologies are evaluated using regional climate data, proxy system model simulations, and maximum latewood density (MXD) data. Analysis of subregional chronologies from the West Highlands and the Cairngorms in the east reveals a higher intensity and more systematic disturbance history in the western subregion, likely a result of extensive timber exploitation. The method improves the climate signal in the two subregional chronologies, particularly in the more disturbed western sites. Our application of this method demonstrates that it is possible to minimise the effects of disturbance in tree-ring width chronologies to enhance the climate signal.

Submergence and Herbivory as Divergent Causes of Marsh Loss in Long Island Sound

Tidal marsh degradation has been attributed to a number of different causes, but few studies have examined multiple potential factors at the same sites. Differentiating the diverse drivers of marsh loss is critical to prescribing successful interventions for conservation and restoration of this important habitat. We evaluated two hypotheses for vegetation loss at two marshes in Long Island Sound (LIS): (1) marsh submergence, caused by an imbalance between sea-level rise and marsh accretion, and (2) defoliation associated with herbivory by the purple marsh crab, Sesarma reticulatum. At our western LIS site, we found no evidence of herbivory: crabs were scarce, and crab-exclusion cages provided no benefit. We attribute degradation at that site to submergence, a conclusion supported by topographic and hydrologic data showing that loss of vegetation occurred only in wetter parts of the marsh. In contrast, at our central LIS site, our observations were consistent with herbivory as a driving force: There were substantial populations of Sesarma, crab-exclusion cages allowed plants to thrive, and vegetation loss took place across a variety of elevations. We also analyzed soil conditions at both sites, in order to determine the signatures of different degradation processes and assess the potential for restoration. At the submergence site, unvegetated soils exhibited high bulk density, low organic content, and low soil strength, posing significant biogeochemical challenges to re-colonization by vegetation. At the herbivory site, unvegetated soils had a characteristic “riddled-peat” appearance, resulting from expansion and erosion of Sesarma burrow networks. The high redox potential and organic content of those soils suggested that revegetation at the herbivory site would be likely if Sesarma populations could be controlled before erosion leads to elevation loss.

Neanderthal's microlithic tool production and use, the case of Tata (Hungary)

Several Western and Central European archaeological sites from the Marine Isotopic Stage (MIS) 5 to 3 yielded microlithic assemblages made by Neanderthals. The European Prehistory lacks a thorough study of these small artifacts to understand their meaning, potential function and to investigate Neanderthal capabilities, behaviours and conception of their tool kit. We propose here to describe the microlithic artifacts from Tata (Hungary) using both typo-technological and functional (usewear analysis) approaches to understand how and what for these tools were made and used. The results show that these stone artifacts were produced using two main reduction sequences. The overall outline of the tools was probably not of great interest for the users which rather looked for artifacts with at least one sharp edge opposite a back. Usewear analysis allowed identification of different activities such as scrapping, cutting, or sawing hard or softer materials. The smallest artifacts may not have been the most used artifacts and that several tools may also have been hafted. The reason why so small artifacts were produced remains unknown. The Neanderthal world (supposedly related to these microlithic sites in Central Europe) was probably developed through multiple techno-morphological solutions.

Serological Survey for Antibodies to Mosquito-Borne Bunyaviruses Among US National Park Service and US Forest Service Employees

Serum samples from 295 employees of Great Smoky Mountains National Park (GRSM), Rocky Mountain National Park (ROMO), and Grand Teton National Park with adjacent Bridger-Teton National Forest (GRTE-BTNF) were subjected to serological analysis for mosquito-borne bunyaviruses. The sera were analyzed for neutralizing antibodies against six orthobunyaviruses: La Crosse virus (LACV), Jamestown Canyon virus (JCV), snowshoe hare virus (SSHV), California encephalitis virus, and Trivittatus virus (TVTV) belonging to the California serogroup and Cache Valley virus (CVV) belonging to the Bunyamwera serogroup. Sera were also tested for immunoglobulin (Ig) G antibodies against LACV and JCV by enzyme-linked immunosorbent assay (ELISA). The proportion of employees with neutralizing antibodies to any California serogroup bunyavirus was similar in all three sites, with the prevalence ranging from 28% to 36%. The study demonstrated a seroprevalence of 3% to CVV across the three parks. However, proportions of persons with antibodies to specific viruses differed between parks. Participants residing in the eastern regions had a higher seroprevalence to LACV, with 24% (18/75) GRSM employees being seropositive. In contrast, SSHV seroprevalence was limited to employees from the western sites, with 1.7% (1/60) ROMO and 3.8% (6/160) GRTE-BTNF employees being positive. Seroprevalence to JCV was noted in employees from all sites at rates of 6.7% in GRSM, 21.7% in ROMO, and 15.6% in GRTE-BTNF. One employee each from ROMO (1.7%) and GRTE-BTNF (1.9%) were positive for TVTV. This study also has illustrated the greater sensitivity and specificity of plaque reduction neutralization test compared to IgG ELISA in conducting serosurveys for LACV and JCV.

Notes on Hysterochelifer afghanicus Beier (Pseudoscorpiones: Cheliferidae), with a key to the species of Hysterochelifer Chamberlin

The pseudoscorpion Hysterochelifer afghanicus Beier, 1966 is redescribed and illustrated based on 21 specimens (13♂, 8♀) collected from different sites in northern, western, and southern Iran. A number of morphological characters and new provincial records are given. In addition, a key for 13 species of the pseudoscorpion genus Hysterochelifer Chamberlin, 1932 is proposed.

Fall migratory patterns of the Blackpoll Warbler at a continental scale

ABSTRACT Blackpoll Warblers (Setophaga striata) breed across Canada and the northern United States and fly across the Atlantic Ocean to South America in fall. Studies of fall migration in this species have centered on the extensive overwater flights but have ignored other aspects of this migration, including potential geographic variation. We used Blackpoll Warbler banding records from 3 coastal (Atlantic seaboard) sites and 9 inland sites to study the fall migration. The sites covered a wide range of the species' geographic distribution during breeding and fall migration in North America. The data spanned the years 1967–2013, though the particular years sampled varied considerably among the stations. We found that the Blackpoll Warbler's fall migration is occurring later by ~1 day decade−1. Young birds generally moved through western sites before adults, whereas at eastern sites the reverse was generally true, which suggests that young birds are taking longer on migration. We also found that young birds ...

Different communities, different choices Human agency and the formation of tableware distribution patterns in Hellenistic Asia Minor

The interpretation of pottery distribution patterns has always been an important analytical endeavour in archaeological approaches to the past. The spatial distribution of pottery has, for example, been queried to identify cultural zones, landscape use, activity areas, and patterns of trade and economic interaction. Pottery distribution patterns can indeed tell us an awful lot about the socio-economic, cultural and geo-political dispositions of the past. Researchers of Classical Greek and Roman pottery have in particular made great strides in this respect and significantly increased our understanding of not only the pottery itself but also the way in which it was produced, distributed, used and discarded. What have not yet received much attention, however, are the formation processes lying behind ceramic distribution patterns observable in the archaeological record. It is precisely with this issue that the present contribution is concerned and by focussing on the Hellenistic tableware distributions of four archaeological sites in (Western) Asia Minor, it will test the importance and role of contextualized human agency with regards to the formation of ceramic distribution patterns.

Drought-induced stomatal closure probably cannot explain divergent white spruce growth in the Brooks Range, Alaska, USA.

Increment cores from the boreal forest have long been used to reconstruct past climates. However, in recent years, numerous studies have revealed a deterioration of the correlation between temperature and tree growth that is commonly referred to as divergence. In the Brooks Range of northern Alaska, USA, studies of white spruce (Picea glauca) revealed that trees in the west generally showed positive growth trends, while trees in the central and eastern Brooks Range showed mixed and negative trends during late 20th century warming. The growing season climate of the eastern Brooks Range is thought to be drier than the west. On this basis, divergent tree growth in the eastern Brooks Range has been attributed to drought stress. To investigate the hypothesis that drought-induced stomatal closure can explain divergence in the Brooks Range, we synthesized all of the Brooks Range white spruce data available in the International Tree Ring Data Bank (ITRDB) and collected increment cores from our primary sites in each of four watersheds along a west-to-east gradient near the Arctic treeline. For cores from our sites, we measured ring widths and calculated carbon isotope discrimination (δ13C), intrinsic water-use efficiency (iWUE), and needle intercellular CO2 concentration (C(i)) from δ13C in tree-ring alpha-cellulose. We hypothesized that trees exhibiting divergence would show a corresponding decline in δ13C, a decline in C(i), and a strong increase in iWUE. Consistent with the ITRDB data, trees at our western and central sites generally showed an increase in the strength of the temperature-growth correlation during late 20th century warming, while trees at our eastern site showed strong divergence. Divergent tree growth was not, however, associated with declining δ13C. Meanwhile, estimates of C(i) showed a strong increase at all of our study sites, indicating that more substrate was available for photosynthesis in the early 21st than in the early 20th century. Our results, which are corroborated by measurements of xylem sap flux density, needle gas exchange, and measurements of growth and δ13C along moisture gradients within each watershed, suggest that drought-induced stomatal closure is probably not the cause of 20th century divergence in the Brooks Range.