ALBERT

Description: Numerous long-term, free-air plant growth facilities currently explore vegetation responses to the ongoing climate change in northern latitudes. Open top chamber (OTC) experiments as well as the experimental set-ups with active warming focus on many facets of plant growth and performance, but information on morphological alterations of plant cells is still scarce. Here we compare the effects of in-situ warming on leaf epidermal cell expansion in dwarf birch, Betula nana in Finland, Greenland, and Poland. The localities of the three in-situ warming experiments represent contrasting regions of B. nana distribution, with the sites in Finland and Greenland representing the current main distribution in low and high Arctic, respectively, and the continental site in Poland as a B. nana relict Holocene microrefugium. We quantified the epidermal cell lateral expansion by microscopic analysis of B. nana leaf cuticles. The leaves were produced in paired experimental treatment plots with either artificial warming or ambient temperature. At all localities, the leaves were collected in two years at the end of the growing season to facilitate between-site and within-site comparison. The measured parameters included the epidermal cell area and circumference, and using these, the degree of cell wall undulation was calculated as an Undulation Index (UI). We found enhanced leaf epidermal cell expansion under experimental warming, except for the extremely low temperature Greenland site where no significant difference occurred between the treatments. These results demonstrate a strong response of leaf growth at individual cell level to growing season temperature, but also suggest that in harsh conditions other environmental factors may limit this response. Our results provide evidence of the relevance of climate warming for plant leaf maturation and underpin the importance of studies covering large geographical scales.

Description: Here we provide the data set of fire proxies from the 77 ha, 32 m deep Lake Czechowskie (53°52′27″N 18°14′12″E, 109 m a.s.l.), northern Poland. The sediment core JC11-K5 was recovered in 2011 in 30 m water depth using an UWITEC gravity corer. JC11-K5 was dated by correlating ten macroscopically visible layers with counted annual layer sequences of adjacent cores and tephra shards related to the Askja eruption in 1875 CE. As a conservative estimate, we assigned a 2σ error of 10 years to the marker layers that we used for calculating the age-depth model in OxCal v. 4.2, a Bayesian age-depth modelling approach that provides posterior age uncertainties. For sedimentary macroscopic charcoal analysis, 1 cm3 of wet sediment was dissolved in water, sieved through a 150-µm mesh. Under a stereomicroscope, macroscopic charcoal of three size classes (150-300, 300-500, and ≥500 µm) was counted continuously throughout the core. To estimate a proxy error that combines sampling, preparation and macrocharcoal counting uncertainties, we continuously sampled short core JC11-K2 between 35-55 cm core depth (n = 20), i.e., interval 1840-1875 CE, that could be linked to core JC11-K5 by four marker layers as determined from varve counting. Samples were processed in the same way as for JC11-K5. The numbers of absolute particles cm-³ were compared with the JC11-K5 samples of the same time interval (n = 31) to determine an overall mean relative standard deviation of 0.8 % of each sample. The topmost 75 samples (1780-2010 CE) were also analyzed for monosaccharide anhydrides (MAs) (n = 75, 1780-2011 CE): 125-250 mg dry sediment were extracted with a DIONEX Accelerated Solvent Extractor (ASE 200, 100 °C, 7.6×106 Pa) using a 9:1 solvent mixture of dichloromethane (DCM):methanol (MeOH). As an internal standard, 2.5-5 ng deuterated levoglucosan (dLVG) was added. The total lipid extracts were separated on an unactivated SiO2 gel column (Merck Si60, grade 7754) using sequential elution with DCM:MeOH (9:1) and DCM:MeOH (1:1). The 1:1 fractions were re-dissolved in 95:5 acetonitrile:H2O and filtered using a 0.45 µm polytetrafluoroethylene filter before analysis. The MAs were analyzed by ultra-high pressure liquid chromatography-high resolution mass spectrometry. Authentic standards for LVG, GAL and MAN were obtained from Sigma Aldrich, and that for dLVG (C6H3D7O5) from Cambridge Isotope Laboratories, Inc. Integrations were performed on mass chromatograms within 3 ppm mass accuracy. Concentrations were corrected for relative response factors to dLVG of 0.997, 0.822, and 2.137 for LVG, MAN, and GAL, respectively. Instrumental (standard) errors for LVG, MAN, and GAL were 4 ± 3, 14 ± 15, and 28 ± 38% (1σ), respectively.

Description: Processed monosaccharide anhydrides records based on the raw data of sediment core JC11-K5 of Lake Czechowskie, N Poland using a robust Monte Carlo based approach that includes age and proxy measurement uncertainties in equally spaced time windows. For details and code see Dietze et al. (2019).

Description: Processed charcoal records based on the raw data of sediment core JC11-K5 of Lake Czechowskie, N Poland using a robust Monte Carlo based approach that includes age and proxy measurement uncertainties in equally spaced time windows. For details and code see Dietze et al. (2019).

Description: JC11-K5 was dated by correlating ten macroscopically visible layers with counted annual layer sequences of adjacent cores and tephra shards related to the Askja eruption in 1875 CE. As a conservative estimate, we assigned a 2σ error of 10 years to the marker layers that we used for calculating the age-depth model in OxCal v. 4.2, a Bayesian age-depth modelling approach that provides posterior age uncertainties.

Description: For sedimentary macroscopic charcoal analysis, 1 cm3 of wet sediment was dissolved in water, sieved through a 150-µm mesh. Under a stereomicroscope, macroscopic charcoal of three size classes (150-300, 300-500, and ≥500 µm) was counted continuously throughout the core. To estimate a proxy error that combines sampling, preparation and macrocharcoal counting uncertainties, we continuously sampled short core JC11-K2 between 35-55 cm core depth (n = 20), i.e., interval 1840-1875 CE, that could be linked to core JC11-K5 by four marker layers as determined from varve counting. Samples were processed in the same way as for JC11-K5. The numbers of absolute particles cm-³ were compared with the JC11-K5 samples of the same time interval (n = 31) to determine an overall mean relative standard deviation of 0.8 % of each sample. The topmost 75 samples (1780-2010 CE) were also analyzed for monosaccharide anhydrides (MAs) (n = 75, 1780-2011 CE): 125-250 mg dry sediment were extracted with a DIONEX Accelerated Solvent Extractor (ASE 200, 100 °C, 7.6×106 Pa) using a 9:1 solvent mixture of dichloromethane (DCM):methanol (MeOH). As an internal standard, 2.5-5 ng deuterated levoglucosan (dLVG) was added. The total lipid extracts were separated on an unactivated SiO2 gel column (Merck Si60, grade 7754) using sequential elution with DCM:MeOH (9:1) and DCM:MeOH (1:1). The 1:1 fractions were re-dissolved in 95:5 acetonitrile:H2O and filtered using a 0.45 µm polytetrafluoroethylene filter before analysis. The MAs were analyzed by ultra-high pressure liquid chromatography-high resolution mass spectrometry using a method adapted from earlier HPLC-ESI/MS2 methods (Hopmans et al., 2013). Authentic standards for LVG, GAL and MAN were obtained from Sigma Aldrich, and that for dLVG (C6H3D7O5) from Cambridge Isotope Laboratories, Inc. Integrations were performed on mass chromatograms within 3 ppm mass accuracy. Concentrations were corrected for relative response factors to dLVG of 0.997, 0.822, and 2.137 for LVG, MAN, and GAL, respectively. Instrumental (standard) errors for LVG, MAN, and GAL were 4 ± 3, 14 ± 15, and 28 ± 38% (1σ), respectively.

Description: Two lakes located in the Kulunda lowland, the biggest part of the Steppe Altai, provide a unique and longest high-resolution records of the environmental history of the Altai Mountain piedmont and adjacent plains. Palaeorecords from lakes, Maloye Yarovoye (53.03 N, 79.11 E, 96 m a.s.l.) and Kuchuk (52.69 N, 79.84 E, 98 m a.s.l.), were studied using several techniques, including pollen and geochemical analyses, quantitative reconstruction of climate and biodiversity using multivariate statistics, and estimation of macrocharcoal accumulation rates and sources of fuel, and radiocarbon dating. Which allowed us to describe the environmental history of the region and to establish the interrelationship between plant biodiversity, climate, and fire dynamics in the Steppe Altai from postglacial time to present day. More details at https://doi.org/10.1016/j.quascirev.2020.106616