Fingerprints of extreme climate events in Pinus sylvestris tree rings from Bulgaria

Tree-ring studies may help better understand climate variability and extreme climate event frequency and are especially useful in regions where detailed meteorological records lack. We studied the effect of droughts and unusually cold periods on Pinus sylvestris tree-ring width and wood anatomy. Study sites were selected along an altitudinal gradient on Vitosha Mountain, Bulgaria. Drought conditions caused the formation of narrow tree rings or light rings if the drought occurred in July-August at the lower altitude sites. In years with droughts in June and the first half of July, followed by precipitation in the middle of July, intra-annual density fluctuations (IADFs) were formed. Trees in the zone with optimal growth conditions produced fewer light rings and narrow rings in years with either strongest droughts or unusually cold summers. At the timberline zone, low summer temperature triggered narrow tree rings and light rings. Frost rings were formed when there was a drop in temperatures below the freezing point in the second half of May or at the beginning of June. Our findings show that studies of tree-ring anatomy may contribute to obtain further knowledge about extreme climatic events in the Balkan Peninsula and in other regions where meteorological data lac

Climate signal in tree-ring chronologies of Pinus peuce and Pinus heldreichii from the Pirin Mountains in Bulgaria

Numerous proxy climate reconstructions have been developed for Europe, but there are still regions with limited data of this kind. One region is the Balkan Peninsula, which is characterized by complex interactions between mountains and climate. We present and discuss two tree-ring chronologies—a 758-year-long one of Pinus heldreichii Christ and 340-year-long one of Pinus peuce Griseb. from treeline locations in the Pirin Mountains in Bulgaria. Climate-growth relationships were computed with bootstrap correlation functions and their consistency over time assessed by calculating the correlations over shortened periods. In addition, we reviewed and analyzed climate situations in years with unusually narrow or wide tree rings. Both species were negatively influenced by previous summer drought conditions and cold winters. Early summer temperatures were positively correlated with P. peuce radial growth, whereas P. heldreichii displayed dependence on summer precipitation. In the second half of the twentieth century, the P. heldreichii trees displayed higher sensitivity to summer drought, which was probably a result of increased summer temperatures and decreased winter precipitation. Our findings contribute to more reliable proxy climate records for the regio

Decay Types and Fungal Communities of Norway Spruce Dead Wood in Europe

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Old World megadroughts and pluvials during the Common Era

Climate model projections suggest widespread drying in the Mediterranean Basin and wetting in Fennoscandia in the coming decades largely as a consequence of greenhouse gas forcing of climate. To place these and other “Old World” climate projections into historical perspective based on more complete estimates of natural hydroclimatic variability, we have developed the “Old World Drought Atlas” (OWDA), a set of year-to-year maps of tree-ring reconstructed summer wetness and dryness over Europe and the Mediterranean Basin during the Common Era. The OWDA matches historical accounts of severe drought and wetness with a spatial completeness not previously available. In addition, megadroughts reconstructed over north-central Europe in the 11th and mid-15th centuries reinforce other evidence from North America and Asia that droughts were more severe, extensive, and prolonged over Northern Hemisphere land areas before the 20th century, with an inadequate understanding of their causes. The OWDA provides new data to determine the causes of Old World drought and wetness and attribute past climate variability to forced and/or internal variability

Protection gaps and restoration opportunities for primary forests in Europe

Aims: Primary forests are critical for forest biodiversity and provide key ecosystem services. In Europe, these forests are particularly scarce and it is unclear whether they are sufficiently protected. Here we aim to: (a) understand whether extant primary forests are representative of the range of naturally occurring forest types, (b) identify forest types which host enough primary forest under strict protection to meet conservation targets and (c) highlight areas where restoration is needed and feasible. Location: Europe. Methods: We combined a unique geodatabase of primary forests with maps of forest cover, potential natural vegetation, biogeographic regions and protected areas to quantify the proportion of extant primary forest across Europe\u27s forest types and to identify gaps in protection. Using spatial predictions of primary forest locations to account for underreporting of primary forests, we then highlighted areas where restoration could complement protection. Results: We found a substantial bias in primary forest distribution across forest types. Of the 54 forest types we assessed, six had no primary forest at all, and in two-thirds of forest types, less than 1% of forest was primary. Even if generally protected, only ten forest types had more than half of their primary forests strictly protected. Protecting all documented primary forests requires expanding the protected area networks by 1,132 km2 (19,194 km2 when including also predicted primary forests). Encouragingly, large areas of non-primary forest existed inside protected areas for most types, thus presenting restoration opportunities. Main conclusion: Europe\u27s primary forests are in a perilous state, as also acknowledged by EU\u27s “Biodiversity Strategy for 2030.” Yet, there are considerable opportunities for ensuring better protection and restoring primary forest structure, composition and functioning, at least partially. We advocate integrated policy reforms that explicitly account for the irreplaceable nature of primary forests and ramp up protection and restoration efforts alike

Jet stream position explains regional anomalies in European beech forest productivity and tree growth.

The mechanistic pathways connecting ocean-atmosphere variability and terrestrial productivity are well-established theoretically, but remain challenging to quantify empirically. Such quantification will greatly improve the assessment and prediction of changes in terrestrial carbon sequestration in response to dynamically induced climatic extremes. The jet stream latitude (JSL) over the North Atlantic-European domain provides a synthetic and robust physical framework that integrates climate variability not accounted for by atmospheric circulation patterns alone. Surface climate impacts of north-south summer JSL displacements are not uniform across Europe, but rather create a northwestern-southeastern dipole in forest productivity and radial-growth anomalies. Summer JSL variability over the eastern North Atlantic-European domain (5-40E) exerts the strongest impact on European beech, inducing anomalies of up to 30% in modelled gross primary productivity and 50% in radial tree growth. The net effects of JSL movements on terrestrial carbon fluxes depend on forest density, carbon stocks, and productivity imbalances across biogeographic regions

Autecology and ex situ growth of Leontopodium nivale subsp. nivale (Asteraceae) from North Pirin marbles (SW Bulgaria)

Kozuharova, E., Panayotov, M. & Spadaro, V.: Autecology and ex situ growth of Leontopodium nivale subsp. nivale (Asteraceae) from North Pirin marbles (SW Bulgaria). — Fl. Medit. 28: 187-206. 2018. — ISSN: 1120-4052 printed, 2240-4538 online. Leontopodium nivale subsp. nivale is a local and disjunct endemic of the central Apennines in Italy and the Pirin Mountains in Bulgaria. The aim of this study is to investigate in situ microhabitat specifics and ex situ ontogenesis regarding the possible future cultivation and to evaluate hazards for wild populations in conditions of human impact and climate change. Leontopodium nivale subsp. nivale is stenobiont which is difficult to grow ex situ and therefore particularly vulnerable. Its wild habitats and populations in Pirin Mts. should be efficiently protected. The results of our study indicate that the stenobiontic plants such as Leontopodium nivale subsp. nivale are particularly subject to hazard

Climate signal in tree-ring chronologies of Pinus peuce and Pinus heldreichii from the Pirin Mountains in Bulgaria

ISSN:0931-1890ISSN:1432-228

Dendroclimatic analysis of Pinus peuce Griseb. at subalpine and treeline locations in Pirin Mountains, Bulgaria

Tree rings are a natural archive containing valuable information about environmental changes. Among the most sensitive ecosystems to such changes are high-mountain forests. Tree-ring series from such locations are exceptionally valuable both for climate reconstructions and for studying the effects of climate changes on forest ecosystems. The objective of our study is to present new long tree-ring width chronologies of Pinus peuce Griseb. from several locations at Pirin Mountains in southwestern Bulgaria, to explore their correlation with monthly temperatures and precipitation in the research area and to assess their potential for climate reconstruction. We built three long-term index chronologies for the radial increment of P. peuce from treeline locations in the study region. The longest chronology spans 675 years. We studied the impact of monthly air temperature and precipitation on its growth for the past 86 years using multiple regression analysis. Our analysis shows that P. peuce growth is positively influenced by high temperatures at the end of the previous growing season, especially at the two sites in Banderitsa valley until the middle of the 1970s, and negatively affected by cold winters. In some of the sample plots its growth was also positively correlated with high summer temperatures. However, even at these high altitudes in some of the locations on steep slopes P. peuce showed signs of negative impact of drought during the hottest summer months (especially in August). Our chronologies contribute to the paleoclimatic record for southwestern Bulgaria, which could provide baseline information about past climate variability and improve our understanding of current and future environmental changes.24 month embargo; published online: 24 April 2020This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]