Intercontinental distributions of species of Cortinarius, subgenus Phlegmacium, associated with Populus in western North America

Quaternary History of Deciduous Forests of Eastern North America and Europe

-This study examines the foraging behavior and habitat selection of a MacGillivray's (Oporornis tolmiei)-Orange-crowned (Vermivora celata)-Wilson's (Wilsonia pusilla) warbler assemblage that occurred on early-growth clearcuts in western Oregon during breeding. Sites were divided into two groups based on the presence or absence of deciduous trees. Density estimates for each species were nearly identical between site classes except for Wilson's, whose density declined on nondeciduous tree sites. Analysis of vegetation parameters within the territories of the species identified deciduous tree cover as the variable of primary importance in the separation of warblers on each site, so that the assemblage could be arranged on a continuum of increasing deciduous tree cover. MacGillivray's and Wilson's extensively used shrub cover and deciduous tree cover, respectively; Orange-crowns were associated with both vegetation types. When the deciduous tree cover was reduced, Orange-crowns concentrated foraging activities in shrub cover and maintained nondisturbance densities. Indices of foraging-height diversity showed a marked decrease after the removal of deciduous trees. All species except MacGillivray's foraged lower in the vegatative substrate on the nondeciduous tree sites; MacGillivray's concentrated foraging activities in the low shrub cover on both sites. Indices of foraging overlap revealed a general pattern of decreased segregation by habitat after removal of deciduous trees. I suggest that the basic patterns of foraging behavior and habitat selection evidenced today in western North America were initially developed by ancestral warblers before their invasion of the west. Species successfully colonizing western habitats were probably preadapted to the conditions they encountered, with new habitats occupied without obvious evolutionary modifications. Received 18 August 1980, accepted 20 February 1981. STUDIES of similar coexisting species usually enumerate ecological differences that presumably reduce the demand upon common resources and allow coexistence (Williams and Batzli 1979). MacArthur's (1958) classic study of niche segregation by sympatric Dendroica, followed by a series of similar studies by Morse (1967, 1968, 1971, 1973, 1976) and Ficken et al. (1968), which dealt with several genera, led to the conclusion that competition for limited resources played the primary role in structuring warbler species assemblages in the eastern United States. The identification of ecological differences alone, however, does not demonstrate the role of competition in structuring avian communities (Schoener 1974). Experimental manipulations are useful means of examining the role of foraging plasticity in species coexistence (Williams and Batzli 1979, Landres and MacMahon 1980). This study was designed to (1) document the foraging behavior, habitat selection, and population densities of a MacGillivray's (Oporornis tolmiei)-Orange-crowned (Vermnivora celata)-Wilson's (Wilsonia pusilla) warbler assemblage that occurred on clearcuts in the Oregon Coast Range, and (2) assess the response of this assemblage to removal of the deciduous tree component on the clearcuts. Results are related to an hypothesis about the formation and structure of western warbler assemblages. The species observed in this study breed commonly in many communities in western North America. In addition, races of the Wilson's Warbler range eastward 5 78 The Auk 98: 578-588. July 1981 This content downloaded from 157.55.39.215 on Wed, 31 Aug 2016 05:01:02 UTC All use subject to http://about.jstor.org/terms July 1981] Western Warbler Assemblages 579 TABLE 1. Description of study sites. Years Site postUSFS size Elevation plantSite name number (ha) (m) Aspect inge Location Deciduous tree (DT) group Bennerb.c 3403-51 21 300-450 NE 5 Lincoln County, Oregon (T14S, R9W; sec. 14, 23) Dill Pickleb 3502-16 31 110-280 NE 7 Lane County, Oregon (T15S, R9W; sec. 17) Non-deciduous tree (ND) group Green Divideb,c 3503-38 36 150-400 N 5 Lane County, Oregon (T15S, R9W; sec. 31) Bear Creekb 3404-51 24 150-370 NE/SE 5 Lincoln County, Oregon (T15S, RlOW; sec. 4, 5) Age of conifer at beginning of study. b Studied in 1979. c Studied in 1980. across Canada and the northern United States to Newfoundland, Ontario, Vermont, and Maine (A.O.U. 1957). These warblers are usually described as common inhabitants of brushlands and second-growth forests, although the Wilson's and, to a lesser extent, the Orange-crown, are often associated with riparian vegetation (Gabrielson and Jewett 1940, Bent 1953). In western Oregon, the species are primarily summer residents, arriving in early May and departing in August or September for southern wintering grounds (Gabrielson and Jewett 1940, A.O.U. 1957). STUDY AREAS AND METHODS

Why red‐dominated autumn leaves in America and yellow‐dominated autumn leaves in Northern Europe?

In the hemiboreal forest zone, the first-generation natural forests of Betula spp., Populus tremula L., and Alnus incana (L.) Moench, which develop after clearcutting on very fertile forest sites, change to deciduous hardwood forests (Quercus robur L., and Fraxinus excelsior L.) due to successive processes. These processes also cause a specific response to the development of undergrowth species, which can have a decisive influence on forest regeneration. The undergrowth species in the mature Betula spp. (Betula pendula Roth. And Betula pubescens Ehrh.), Populus tremula, and Alnus incana forest stands were evaluated to provide knowledge on undergrowth species composition and development under different soil conditions, and to identify the forest stand age’s impact on undergrowth species. The evaluation was based on the standwise forest inventory data and limited to the analysis of pioneer tree species forests usually developed as first-generation natural forests after clearcutting. The study results showed that deciduous forests have rich undergrowth species diversity with a dominance of the Corylus avellana L., Padus avium L., Frangula alnus Mill., Sorbus aucuparia L., and Salix spp., which are typical undergrowth species in the hemiboreal forest zone. The dense and medium density undergrowth with the predominant Corylus avellana was rather common in the Betula spp. and Populus tremula stands; and Padus avium was more abundant in the Alnus incana stands on very fertile sites. Larger areas with dense undergrowth were obtained in the low mixed and mixed Alnus incana stands than in the pure stands, while no clear relationship between the stand mixture and undergrowth density was obtained in the Betula spp. and Populus tremula stands. The area of Corylus avellana significantly increased, while the area of Padus avium decreased in all studied forests with increasing stand age. Other dominant undergrowth species–Sorbus aucuparia, Frangula alnus, and Salix spp.–decreased with increasing age of the Betula spp. and Populus tremula stands. In the context of biodiversity, a higher number of undergrowth species was obtained in the mixed Betula spp. stands than in the pure and low mixed stands. New insights about the undergrowth species and their development patterns under the canopy of pioneer deciduous forests on very fertile soils were provided. However, these findings do not strongly suggest that an unmanaged forest regime wins over conventional forest management in mature and older deciduous forests on fertile soils as regards the biodiversity and other ecological services provided by the undergrow species.

Phylogenomics, co-evolution of ecological niche and morphology, and historical biogeography of buckeyes, horsechestnuts, and their relatives (Hippocastaneae, Sapindaceae) and the value of RAD-Seq for deep evolutionary inferences back to the Late Cretaceous

Diurnal bird communities in Southeast Alaska and adjacent Canada, censured in 1992-1994, sometimes had higher diversity and abundance in deciduous than coniferous forest. However, variation within each broad vegetation type and among years obscured any general pattern. Furthermore, rarefaction curves did not differ between forest types and a wider comparison between the communities of deciduous and coniferous forests in western North America was variable in both magnitude and direction. Thus, there is little evidence for a general trend toward greater diversity in bird communities of western and northern deciduous forests. Both deciduous and coniferous forests of the far north are geologically young, and there was some evidence that deciduous forest, at least, may not be saturated with bird species. Certain species were missing or shifted from conifer habitat elsewhere to deciduous habitat in our area. Coastal islands with coniferous forest and mainland patches of deciduous habitat supported about as many species as expected from the number of individuals present. A small number of bird species dominated the community at each site, but the dominant species differed considerably among locations. Proportional similarity of coastal and interior forest was low, except for locations at the north end of the Inside Passage, which supported species characteristic of both coastal and interior forests. The similarity of community composition in deciduous and coniferous stands was also low, especially on the coast.

Wood growth phenology and its relationship with leaf phenology in deciduous forest trees of the temperate zone of Western Europe

The origin of characteristic increase of continental-scale summer surface temperature in decades over Northern hemisphere was investigated. July-temperature in Europe, East Asia, the North Pacific, and western North America have been undergoing more increase than the global average of about 1ºC increase, especially in recent years. On the contrary, MME of 37 CMIP5 models do not show the focused regional warming hot-spots but exhibits hemispheric surface temperature increase. From the comparison between GISTEMP observation record and CMIP5 MME historical data, we show an evidence that the observed characteristic increase of regional temperature for the recent 43 years is dominated by the Internal Climate Variability (ICV) of decadal time-scale. Performing EOF analysis on the ICV, the four dominant modes are identified as Pacific Decadal Oscillation (PDO), North Pacific Oscillation (NPO), Pacific Meridional Mode (PMM), and Atlantic Multi-decadal Oscillation (AMO). It is also shown that, with only two dominant modes among those modes, large portion of continental-scale temperature increase can be explained: We show that PDO and PMM are dominant modes in Europe and East Asia, NPO and AMO in the North Pacific, and PDO and NP in western North America. The observed sub-trend is nicely reproduced with only these two modes. Quantitatively, the observed sub-trend from ICV explains 73%, 60%, 55%, and 18% of the total variability in North Pacific, East Asia, western North America and Europe, respectively. Note that, despite 82% of temperature fluctuation in Europe is attributed by the external forcing, 18% of the internal variability is still important to explain the increasing number of extreme heat events in Europe in recent several decades.

Climate model output is used to analyze the behavior of extreme cold-air outbreaks (CAOs) under recent and future climatic conditions. The study uses daily output from seven GCMs run under late-twentieth century and projected twenty-first century radiative conditions (SRES A1B greenhouse gas emission scenario). We define a CAO as an occurrence of two or more consecutive days during which the local mean daily surface air temperature is at least two standard deviations below the local wintertime mean temperature. In agreement with observations, the models generally simulate modern CAOs most frequently over western North America and Europe and least commonly over the Arctic. These favored regions for CAOs are located downstream from preferred locations of atmospheric blocking. Future projections indicate that CAOs—defined with respect to late-twentieth century climatic conditions—will decline in frequency by 50 to 100% in most of the Northern Hemisphere during the twenty-first century. Certain regions, however, show relatively small changes and others actually experience more CAOs in the future, due to atmospheric circulation changes and internal variability that counter the thermodynamic tendency from greenhouse forcing. These areas generally experience greater near-surface wind flow from the north or the continent during the twenty-first century and/or are especially prone to atmospheric blocking events. Simulated reductions in CAOs are smallest in western North America, the North Atlantic, and in southern regions of Europe and Asia. The Eurasian pattern is driven by a strong tendency for the models to produce sea-level pressure (SLP) increases in the vicinity of the Mediterranean Sea (intermodel mean of 3 hPa), causing greater advection of continental air from northern and central Asia, while the muted change over western North America is due to enhanced ridging along the west coast and the increased frequency of blocking events. The North Atlantic response is consistent with a slowdown of the thermohaline circulation, which either damps the warming regionally or results in a cooler mean climate in the vicinity of Greenland. Copyright © 2006 Royal Meteorological Society.

This study quantifies the association between the COVID‐19 economic downturn and 2020 tropospheric ozone anomalies above Europe and western North America, and their impact on long‐term trends. Anomaly detection for an atmospheric time series is usually carried out by identifying potentially aberrant data points relative to climatological values. However, detecting ozone anomalies from sparsely sampled ozonesonde profiles (once per week at most sites) is challenging due to ozone's high temporal variability. We first demonstrate the challenges for summarizing regional trends based on independent time series from multiple nearby ozone profiling stations. We then propose a novel regional‐scale anomaly detection framework based on generalized additive mixed models, which accounts for the sampling frequency and inherent data uncertainty associated with each vertical profile data set, measured by ozonesondes, lidar or commercial aircraft. This method produces a long‐term monthly time series with high vertical resolution that reports ozone anomalies from the surface to the middle‐stratosphere under a unified framework, which can be used to quantify the regional‐scale ozone anomalies during the COVID‐19 economic downturn. By incorporating extensive commercial aircraft data and frequently sampled ozonesonde profiles above Europe, we show that the complex interannual variability of ozone can be adequately captured by our modeling approach. The results show that free tropospheric ozone negative anomalies in 2020 are the most profound since the benchmark year of 1994 for both Europe and western North America, and positive trends over 1994–2019 are diminished in both regions by the 2020 anomalies.

Nephroma occultum is a COSEWIC listed cyanolichen of “Special Concern”. It is endemic to old-growth cedar-hemlock forests in western North America. This is the first study to place N. occultum into a phylogenetic framework using nucleotide sequence and secondary structure data. It also addresses the phylogenetic relationship between N. occultum and N. arcticum. Analysis of fungal Internal Transcribed Spacer (ITS) ribosomal DNA (rDNA) produced four major clades. The cyanobacterial transfer RNALeu intron (tRNALeu) from N. occultum was separated from that of N. isidiosum and fell between the Eurasian and North American epiphytic taxa. Examination of length and complexity of the folded secondary structures revealed different trends in the ITS1 and ITS2 rRNA regions. Even though N. occultum is endemic to North America, it seems more closely related to South American temperate rainforest species than to the sympatric N. arcticum. Nephroma occultum is alone among the studied species of Peltigerales in having an exceptionally long ITS1 region, and a different tRNALeu intron DNA sequence of the photobiont suggesting association with a unique genotype of Nostoc. It may be argued that the fitness of N. occultum may be influenced by the complex ITS1 RNA structure, a unique photobiont genotype undergoing a genetic bottleneck, no sexual reproduction to generate variation, and the inability to associate with different photobionts to adapt to changing habitats.

Marginal Rate of Transformation and Rate of Substitution measured by DEA environmental assessment: Comparison among European and North American nations

Since 2000, swathes of energy experts, government officials, industry representatives and journalists have predicted the emergence of a global ‘nuclear renaissance.’ Nuclear energy was said to be on the precipice of a new era of development, characterised by widespread construction of new nuclear reactors and a concomitant increase in global nuclear capacity. Despite this expectation, there is little evidence to date which suggests that a revival of nuclear power has taken place in the regions of Western Europe and North America in the way that the rhetoric depicted. This thesis therefore seeks to firstly establish that there is a disjuncture between the rhetoric and reality of the nuclear renaissance in Western Europe and North America, and secondly, to explain why this disjuncture exists. Academic and journalistic debate over recent developments in civil nuclear energy policy has tended to focus on two key reasons for why there has not been a widespread expansion of nuclear energy in these regions. Firstly, that the nuclear disaster at Fukushima in 2011 reignited concerns over nuclear safety, thereby eroding public and political support for nuclear new build. Secondly, that the economic problems facing nuclear development continued to act as a major disincentive to the construction of new nuclear power plants. However, the global applicability of these two issues means that neither of these explanations can explain why the nuclear renaissance appears to have failed in Western Europe and North America, while nuclear new build is expanding in other parts of the world. Moreover, the revival of safety concerns post-Fukushima fails to explain why there was little evidence of a nuclear renaissance taking place prior to March 2011. This thesis provides a contribution to knowledge by adopting a more holistic and inductive approach for understanding why there is a disjuncture between the expectation and reality of the nuclear renaissance in Western Europe and North America. It challenges existing explanations for the failure of the nuclear renaissance as being simplistic, mono-causal and a-historical. This thesis disputes the idea that the absence of a widespread expansion of nuclear energy and the apparent failure of the nuclear renaissance can be attributed to any one problem or event. Instead, it embraces the simple premise that a broad range of contextual factors must be explored in order to fully understand why the rhetoric of a nuclear renaissance has not become a reality. An extensive analysis of government, industry and media documents published from 1945 onwards, as well as interviews with experts in nuclear energy policy, was undertaken in order to establish a better understanding of how and why nuclear energy development changes over time. Through this process, it became clear that the reasons typically cited for explaining changes in nuclear development are ‘nuclear-specific factors’. That is, factors relating directly to the construction and operation of nuclear power plants – such as the economics of nuclear energy, the safety of nuclear power plants, and the storage and disposal of nuclear waste. While these factors undeniably play an important role in influencing nuclear new build, focusing solely on these nuclear-specific factors obscures the impact of broader social, political, and contextual changes on nuclear energy development. This thesis draws upon political science literature to argue that the changing trajectory of nuclear energy development has also been influenced by broader contextual shifts in the post-war era. The impact of four ‘contextual factors’ on nuclear power are examined: the rise of environmentalism, the decline in public trust in government, changes in risk perception, and the rise of neoliberalism. Each of these contextual shifts have changed the way in which agents think about and respond to the issue of nuclear power. Consequently, this thesis argues that both nuclear-specific factors and contextual factors are important in explaining change in civil nuclear energy development. All of these factors are dynamic and interactive, mutually shaping and influencing one another. Moreover, both of these groups of factors have contributed to the failure of the nuclear renaissance in Western Europe and North America. The ongoing presence of these challenges will continue to hamper the future success of civil nuclear energy development, and prevent a nuclear renaissance from taking place.

Information on forest structure is vital for sustainable forest management. Currently, airborne LiDAR remote sensing has been well established as an effective tool to characterize the structure of canopies and forest inventory variables. Radiometry and geometry are highly intertwined in LiDAR remote sensing of forest vegetation and phenology influences the geometric-optical properties of deciduous and evergreen trees causing seasonal variation in LiDAR observations. This variation may be considered as a nuisance or exploited in for example tree species identification. Airborne LiDAR data are also influenced by sensor functioning, acquisition settings, scan geometry and the atmosphere. Reliable estimation of subtle phenological effects calls for data in which the impact of the external factors is minimal. We experimented with such data and explored LIDAR waveforms (WFs) in boreal trees in winter, early summer and late summer. Our objectives were to i) assess the match of the multitemporal LiDAR data for observing true changes in vegetation; ii) quantify the influence of phenology in deciduous and evergreen trees; iii) study the effect of varying scan zenith angle (SZA) and canopy age on WF features in different phenostates; iv) assess the temporal feature correlation in individual living and dead standing trees. A WF-recording pulsed LiDAR sensor unit operating at the wavelength of 1550 nm was used in repeated acquisitions. WF attributes such as energy, peak amplitude and echo width were derived for each pulse and were localized vertically to crown, understory and ground components. Silver and downy birch, black alder, European aspen, Siberian larch, Scots pine, Norway spruce and dead standing spruce formed our strata. Results showed that phenology caused more variation in WF features of deciduous trees compared to evergreen conifers. Deciduous trees displayed substantial between-species variation that was linked with differences in branching pattern, leaf orientation and bark reflectance. Pine displayed a possible winter-early summer anomaly in canopy backscattering that may be linked with changes in foliage clumping or with the role of stamens in early summer trees. Trees displayed positive temporal correlation in WF features and correlations were the strongest in evergreen and deciduous conifers and decreased with time. SZA had minor influence on WF features whereas age exercised a strong effect on many features with parallel variation between species and phenostates. Structural changes following death, i.e. ‘aging’ changed the geometric WF features of dead standing trees. Our results provide new insights for enhancing tree species identification by using WF LiDAR and for LiDAR time-series analysis of vegetation.

The American quaking aspen (Populus tremuloides Michx.) and its close relative, the Eurasian quaking aspen (Populus tremula L.), cover a realm that is perhaps the most expansive of all tree species in the world. In North America, sudden aspen decline (SAD) is a growing concern that marks the rapid decline of quaking aspen trees leading to mortality at the stand and landscape scale. Research suggests that drought and water stress are the primary causes of SAD. Predisposing factors (age, structure, and landscape position), as well as associated stressors (i.e., pests and pathogens), have been linked to mortality in affected stands. The conflation of multiple interacting factors across the aspen’s broad geographic range in North America has produced significant debate over the classification of SAD as a disease and the proper management of affected stands. Interestingly, no such effects have been reported for the Eurasian aspen. We here review and synthesize the growing body of literature for North America and suggest that SAD is a novel decline disease resulting from multiple inciting and interacting factors related to climate, land-use history, and successional dynamics. We suggest that the range of aspen observed at the onset of the 21st Century was bolstered by a wet period in western North America that coincided with widespread regional cutting and clearing of late-successional forests for timber and grazing. No comparable land-use history, successional status, or age-class structure is apparent or linked for Eurasian forests. Eurasian aspen is either absent or young in managed forests, or old and decadent in parks in Fenno-Scandinavia, or it grows more intimately with a more diverse mixture of tree species that have arisen from a longer period of frequent timber cutting in Russia. Based on these insights we provide recommendations for practical management techniques that can promote stand resilience and recovery across a range of stand conditions in North America. Managers should attempt to identify SAD-prone stands using the presence of predisposing conditions and focus treatments such as coppice or prescribed fire on stands with suitable topographies, elevations, and climates. We conclude that SAD will persist throughout the coming decades, given the enormity of past cutting history, fire exclusion, and current changes in climate until a more active restoration agenda is implemented.