Late Holocene Vegetation History of Grevena Province, Northwestern Greece

<p>Palynological investigations aimed at reconstructing the vegetation history of the Grevena Province, northwestern Greece were conducted in association with an archaeological research project. Fossil pollen, spores, microscopic charcoal particles, and sediment stratigraphies of radiocarbon-dated sediment cores from three sites in pine, beech, and oak woodland zones provide evidence of climatic changes, land use, and erosion during the last 3500 years. Identification of pollen and spores was aided by an extensive reference collection of local species and construction of a pollen key modelled on that of Faegri & Iversen (1989). Extant vegetation units are characterized by their contemporary pollen assemblages. Surface samples collected along an elevational transect show that a fairly direct relationship exists between the major vegetation zones and pollen deposition: pine, beech, and oak pollen predominate in their respective zones. Over-representation of pine pollen is notable. The sequence from Gomara site in the pine wood-pasture zone at 1750 m asl covers the time span c. 1340 BC to 700 AD. A local open pine wood was gradually replaced by beech after c. 890 BC, perhaps through reduced disturbance and/or increased precipitation. A herbaceous pollen spike at c. 80 BC resulted from deposition of volcanic ash. Pine wood replaced beech at c. 330 AD. Two periods of accelerated erosion coincide with the pine wood phases and with anthropogenic burning and grazing. These periods are separated by a period of abandonment when the climate was probably wetter. The sequence from Anelia site in the beech wood zone at 1440 m asl spans c. 1560-1989 AD. The site was surrounded by beech wood for the duration of the sequence. Regional and local burning of vegetation is indicated by an abundance of microscopic charcoal particles from c. 1560 until c. 1730 AD, when it ceased. Periods of erosion occurred during this period. After c. 1730 AD a homogeneous peat formed on the wetland, suggesting a period of greater landscape stability. From pollen evidence, a variety of land-use practices such as cereal cultivation, grazing, coppicing, and lumbering were carried out in the vicinity of the site especially before c. 1730 AD, but these diminished after 1920 AD. The lower part of the sequence from Kellia site in the oak wood-steppe zone at 580 m asl is insecurely dated, but the upper part spans c. 1230-1989 AD. The lowlands were covered with deciduous/semi-evergreen oak woods for the duration of the sequence. Since c. 1230 AD land close to the site was intensively cultivated with a variety of cereals. Burning occurred frequently throughout the period. The ratio of deciduous to semi-evergreen oak pollen is correlated with temperature and indicates a decline from c. 1230-1680 AD, after which temperature increased, a pattern similar to that of the Little Ice Age. Frontispiece The cultural landscape of Grevena Province looking NE towards the Vourinos Mountains on the eastern border of Grevena, from a prominent hill about 1 1/4 km NW of the modern village of Itea. In the foreground is the stubble of a wheat field. Beyond is an 18th century church dedicated to Aghia Panaghia. The middle ground is the steppe oak wood pasture of Grevena plains. Recent erosion on the sides of gullies can be seen here, even though they appear to be well vegetated. Frescoes in the church are shown in the enlargement. It stands on a registered archaeological site, Grevena Project 108 (21 degrees 36.18' E, 40 degrees 04.29' N, 640 m asl) that covers more than 10,000 m2. Archaeological evidence dating to Early Iron Age, Archaic, Classical, Hellenistic, Roman, Early Medieval and Ottoman periods has been recorded.</p>

Late Holocene Vegetation History of Grevena Province, Northwestern Greece

<p>Palynological investigations aimed at reconstructing the vegetation history of the Grevena Province, northwestern Greece were conducted in association with an archaeological research project. Fossil pollen, spores, microscopic charcoal particles, and sediment stratigraphies of radiocarbon-dated sediment cores from three sites in pine, beech, and oak woodland zones provide evidence of climatic changes, land use, and erosion during the last 3500 years. Identification of pollen and spores was aided by an extensive reference collection of local species and construction of a pollen key modelled on that of Faegri & Iversen (1989). Extant vegetation units are characterized by their contemporary pollen assemblages. Surface samples collected along an elevational transect show that a fairly direct relationship exists between the major vegetation zones and pollen deposition: pine, beech, and oak pollen predominate in their respective zones. Over-representation of pine pollen is notable. The sequence from Gomara site in the pine wood-pasture zone at 1750 m asl covers the time span c. 1340 BC to 700 AD. A local open pine wood was gradually replaced by beech after c. 890 BC, perhaps through reduced disturbance and/or increased precipitation. A herbaceous pollen spike at c. 80 BC resulted from deposition of volcanic ash. Pine wood replaced beech at c. 330 AD. Two periods of accelerated erosion coincide with the pine wood phases and with anthropogenic burning and grazing. These periods are separated by a period of abandonment when the climate was probably wetter. The sequence from Anelia site in the beech wood zone at 1440 m asl spans c. 1560-1989 AD. The site was surrounded by beech wood for the duration of the sequence. Regional and local burning of vegetation is indicated by an abundance of microscopic charcoal particles from c. 1560 until c. 1730 AD, when it ceased. Periods of erosion occurred during this period. After c. 1730 AD a homogeneous peat formed on the wetland, suggesting a period of greater landscape stability. From pollen evidence, a variety of land-use practices such as cereal cultivation, grazing, coppicing, and lumbering were carried out in the vicinity of the site especially before c. 1730 AD, but these diminished after 1920 AD. The lower part of the sequence from Kellia site in the oak wood-steppe zone at 580 m asl is insecurely dated, but the upper part spans c. 1230-1989 AD. The lowlands were covered with deciduous/semi-evergreen oak woods for the duration of the sequence. Since c. 1230 AD land close to the site was intensively cultivated with a variety of cereals. Burning occurred frequently throughout the period. The ratio of deciduous to semi-evergreen oak pollen is correlated with temperature and indicates a decline from c. 1230-1680 AD, after which temperature increased, a pattern similar to that of the Little Ice Age. Frontispiece The cultural landscape of Grevena Province looking NE towards the Vourinos Mountains on the eastern border of Grevena, from a prominent hill about 1 1/4 km NW of the modern village of Itea. In the foreground is the stubble of a wheat field. Beyond is an 18th century church dedicated to Aghia Panaghia. The middle ground is the steppe oak wood pasture of Grevena plains. Recent erosion on the sides of gullies can be seen here, even though they appear to be well vegetated. Frescoes in the church are shown in the enlargement. It stands on a registered archaeological site, Grevena Project 108 (21 degrees 36.18' E, 40 degrees 04.29' N, 640 m asl) that covers more than 10,000 m2. Archaeological evidence dating to Early Iron Age, Archaic, Classical, Hellenistic, Roman, Early Medieval and Ottoman periods has been recorded.</p>

Birch-naïve, oak-allergic subjects’ response to birch pollen in an environmental chamber

BACKGROUND: Oak and birch pollens are known to have strong cross-reactivity. It is unknown how robust this cross-reactivity is in subjects without natural exposure to pollen of both trees. We aimed to assess in an Allergen Challenge Chamber (ACC), the symptomatic responsiveness to birch pollen in subjects allergic to and naturally exposed to Virginia Live Oak (VLO) pollen and SPT-sensitive but not naturally exposed to birch pollen. METHODS: Subjects underwent SPT and blood draw for ssIgE to oak and birch antigens. Residential historical data were obtained. Subjects were exposed to birch pollen (3,500 ±700 gr/m ) in 2 consecutive 3-hour challenges. Symptoms were recorded at baseline and 30-minute intervals. RESULTS: Twenty-four subjects, 12 males, age 20-58 yrs, completed the study. Sixteen subjects (66.7%) responded with high total symptom scores (TSS) ≥10 of max 21. Twelve subjects (50%) had ssIgE ≥0.70 kU/L to oak. Subjects with a Class II ssIgE to oak pollen had a significantly higher max TSS than those without. Fifteen subjects without natural exposure to birch pollen responded with TSS equivalent to 9 with previous natural exposure. Those without natural birch exposure also responded similarly to subjects in birch endemic areas reported in the literature. CONCLUSION: Subjects allergic to oak pollen residing in South Texas, responded to birch pollen in an ACC with symptoms comparable to both those with previous exposure and also those residing in endemic areas and reported by other researchers. This robust response of cross-reactivity in oak-allergic subjects, without prior endemic exposure, suggests that a cross-reactive intervention could be efficacious.

Allergy to oak pollen in North America

Background: Oak pollen is an important allergen in North America. The genus Quercus (oak) belongs to the family Fagaceae under the order Fagales. Objective: The objective of this article was to narratively review the oak pollen season, clinical and epidemiologic aspects of allergy to oak pollen, oak taxonomy, and oak allergen cross-reactivity, with a focus on the North American perspective. Methods: A PubMed literature review (no limits) was conducted. Publications related to oak pollen, oak-related allergic rhinitis with or without conjunctivitis, and oak-related allergic asthma were selected for review. Results: Oak species are common throughout the United States and contribute up to 50% to overall atmospheric pollen loads. Mean peak oak pollen counts can reach >2000 grains/m3. The start of the oak pollen season generally corresponds to the seasonal shift from winter to spring based on latitude and elevation, and may begin as early as mid February. The duration of the season can last > 100 days and, in general, is longer at lower latitudes. In the United States, ∼30% of individuals with allergy are sensitized to oak. The oak pollen season correlates with increased allergic rhinitis symptom‐relieving medication use and asthma-related emergency department visits or hospitalizations. Oak falls within the birch homologous group. Extensive immunologic cross-reactivity has been demonstrated between oak pollen and birch pollen allergens, and, more specifically, their major allergens Que a 1 and Bet v 1. The cross-reactivity between oak and birch has implications for allergy immunotherapy (AIT) because guidelines suggest selecting one representative allergen within a homologous group for AIT, a principle that would apply to oak. Conclusion: Allergy to oak pollen is common in North America and has a substantial clinical impact. Oak pollen allergens are cross-reactive with birch pollen allergens, which may have implications for AIT.

Oak pollen concentration in the air of selected Polish cities in 2020

The study aims to compare the oak pollen season in selected Polish cities; Bialystok, Bydgoszcz, Cracow, Katowice, Piotrkow Trybunalski, Lublin, Olsztyn, Opole, Szczecin, Warsaw, and Wroclaw in 2020. Measurements were made using the volumetric method, with a Hirst-type sampler. Oak pollen season, defined as the period with 98% of the annual total catch, started between 14 (in Opole) and 25 April (in Lublin). The season ended on 1 June at the latest; in Sosnowiec, Bydgoszcz, Olsztyn, and Bialystok. It lasted from 30 to 47 days (37 days on average). The maximum daily oak pollen concentrations were observed between 24 April and 11 May. The highest annual sum of oak pollen grains (SPI) was recorded in Lublin, while the lowest in Bialystok. The highest concentrations of 596 oak pollen grains/m3 were noted in Lublin on 28 April. The longest exposure to high concentrations of oak pollen (>91 grains/m3), lasting 12-13 days, was recorded in Lublin, Opole, and Wroclaw.

Late-Holocene climate changes linked to ecosystem shifts in the Northwest Wisconsin Sand Plain, USA

Records of century-scale climate variability in the Upper Midwest generally agree that moisture availability increased between 4000 and 3000 cal. yr BP (calendar years before present = 1950 CE), and that there were large, frequent droughts 1000–700 cal. yr BP followed by wetter/cooler conditions. Variability among regional sites, however, remains problematic. In this study we reconstruct climate on the Northwest Wisconsin Sand Plain (NWSP), USA, to identify potential climatic drivers of previously documented changes in vegetation and fire regimes. Oak pollen was replaced by pollen from xeric pine taxa at several sites on the NWSP ~1425 cal. yr BP, accompanied by a change to larger, less frequent charcoal peaks. Another major vegetation change occurred ~700 cal. yr BP, when pollen of the more mesic P. strobus L. (white pine) increased and charcoal influx decreased. We used a vegetation-independent lake-level record to determine whether long-term changes in moisture availability were associated with these ecosystem changes. Decreases in percent organic matter in shallow-water sediment cores from Cheney Lake indicate that the lake level decreased sharply ~1500 cal. yr BP, consistent with the interpretation that the changes in vegetation and fire regime were driven by a severe and previously undocumented drought. The lake level rose again, reaching approximately modern levels by 800–700 cal. yr BP, consistent with the hypothesis of cooler/wetter conditions in the Upper Midwest in the past ~700 years and with the expansion of mesic taxa on the NWSP 700 cal. yr BP.

Pollen Production of Quercus in the North-Western Iberian Peninsula and Airborne Pollen Concentration Trends during the Last 27 Years

Natural forests are considered a reservoir of great biological diversity constituting one of the most important ecosystems in Europe. Quercus study is essential to assess ecological conservation of forests, and also of economic importance for different industries. In addition, oak pollen can cause high sensitization rates of respiratory allergies in pollen-allergy sufferers. This study sought to know the pollen production of six oak species in the transitional area between the Eurosiberian and Mediterranean Bioclimatic Regions, and to assess the impact of climate change on airborne oak pollen concentrations. The study was conducted in Ourense (NW Spain) over the 1993–2019 period. A Lanzoni VPPS 2000 volumetric trap monitored airborne pollen. A pollen production study was carried out in ten trees randomly selected in several Quercus forest around the Ourense city. Oak pollen represented around 14% of annual total pollen registered in the atmosphere of Ourense, showing an increasing trend during the last decade. Pollen production of the six studied oak species follow the proportions 1:1:2:5:90:276 for Q. ilex, Q. faginea, Q. rubra, Q. suber, Q. pyrenaica, and Q. robur respectively. We detected a significant trend to the increase of the annual maximum temperature, whereas a decrease of the maximum and mean temperatures during three previous months to oak flowering. This could be related with the detected trend to a delay of the oak Main Pollen Season onset of 0.47 days per year. We also found significant trends to an increase of the annual pollen integral of 7.9% pollen grains per year, and the pollen peak concentration of 7.5% pollen grains per year. Quercus airborne pollen monitoring as well as the knowledge of the reproductive behavior of the main oak species, bring us an important support tool offering a promising bio-indicator to detect ecological variations induced by climate change.