Relationships between vegetation types and soil properties along a topographical gradient on the northern coast of the Brgger Peninsula, Svalbard

Vegetation patterns in the high Arctic vary not only with proglacial chronosequence but also with a topographical gradient on older deglaciated areas which are covered by mature vegetation. A preliminary survey of local scale vegetation patterns along a topographical gradient with special reference to soil properties was conducted on the northern coast of the Brgger Peninsula, Svalbard in the high Arctic. Three community types of vascular plants were distinguished by common dominants: Cardamine type, Salix type and Oxyria/Luzula type. Each community type was comprised of different habitat types. The Cardamine type was restricted to near the bottom of depressions, where there was high soil water content. The Oxyria/Luzula type was characterized by habitats belonging to upper slopes to ridges, having high gravel content soils. On the other hand, the habitat preference of the Salix type, which had higher vegetation cover and biomass of vascular plants compared to the other two types, was not clear. The core habitat of fertile/undisturbed area, as described by the centrifugal community organization model, might be dominated by Salix polaris in this area. The other species had a refugium from interspecific competition in their preferred peripheral habitats such as exposed ridge or wetland

The methane flux along topographical gradients on a glacier foreland in the High Arctic, Ny-Alesund, Svalbard

In order to examine the relationship between the methane (CH_4) flux and soil factors and vegetation in High Arctic tundra, we investigated the CH_4 flux along topographical gradients on a glacier foreland in Ny-Alesund, Svalbard (79°N, 12°E). The CH4 flux rates varied widely among sites even within the same vegetation type, ranging from positive (emission) to negative (absorption) values. High CH_4 emission rates were detected on ridges and in sites with a low soil water content, but there was no significant relationship between CH_4 flux rates and soil factors including soil moisture, pH, soil carbon and nitrogen content. Mean values of CH_4 emission and CH_4 absorption were 0.30±0.33 mg m^(-2) h^(-1) (n=12) and 0.11±0.06 mg m^(-2) h^(-1) (n=11), respectively. These findings suggest that the study area is a small source of CH_4 with a mean flux of 0.11 mg CH_4 m^(-2) h^(-1) (0.083 mg C m^(-2) h^(-1)). It was concluded that carbon flux derived from CH_4 accounts for an extremely small proportion of the total carbon flux from soil in this area

Vegetation development and carbon storage on a glacier foreland in the High Arctic, Ny-Ålesund, Svalbard

AbstractThe distribution of organic carbon and its relationship to vegetation development were examined on a glacier foreland near Ny-Ålesund, Svalbard (79°N). In a 0.72-km2 area, we established 43 study plots on three line transects along primary succession from recently deglaciated area to old well-vegetated area. At each plot, we measured the type and percent coverage of vegetation types. The organic carbon content of vegetation, organic soil, and mineral soil samples was determined based on their organic carbon concentration and bulk density. Cluster analysis based on vegetation coverage revealed five types of ground surfaces representing variations in the amounts and allocation patterns of organic carbon. In the later stages of succession, 7%–24% and 31%–40% of organic carbon was contained in the organic and deeper soil layers, respectively. Organic carbon storage in the later stages of succession ranged from 1.1 – 7.9 kg C m−2. A larger amount of organic carbon, including ancient carbon in a raised beach deposit, was expected to be contained in much deeper soil layers. These results suggest that both vegetation development and geological history affect ecosystem carbon storage and that a non-negligible amount of organic carbon is distributed in this High Arctic glacier foreland

Synthesis of methylcellulose model copolymers with heterogeneous distribution and their solution properties

In order to elucidate the characteristic features of commercial methylcellulose precisely, O-methylcellulose model copolymers consisting of 2, 3, 6-tri-O-methylanhydroglucose unit (236MeAGU) and 2-O-methylanhydroglucose unit (2MeAGU) with various composition ratios were synthesized via cationic ring-opening copolymerization of the corresponding glucose orthoester derivatives, subsequent removal of pivaloyl and allyl groups, and methylation. The structure of the obtained copolymers was confirmed by 1H-, 13C-NMR, and FT-IR. Temperature-dependent turbidity measurement verified their thermoresponsive behavior in aqueous solution. The lower critical solution temperature was tuned from 63 to 45 °C above 47 mol-% 236MeAGU content. The hydrophobicity along the cellulose chain was dominant to determine their physical properties. However, the aqueous properties of the MC model copolymers were strongly affected by the slight difference of the composition ratio. The present method would provide further details of the structure–property relationship of O-methylcellulose

Reactivity of syringyl quinone methide intermediates in dehydrogenative polymerization I: high-yield production of synthetic lignins (DHPs) in horseradish peroxidase-catalyzed polymerization of sinapyl alcohol in the presence of nucleophilic reagents

It is known that the conventional dehydrogenative polymerization of sinapyl alcohol (S-alc) gave syringyl synthetic lignins (S-DHPs), but in extremely low yields. In this article, to examine the contribution of syringyl quinone methide intermediates (S-QM) on S-DHP production, horseradish peroxidase (HRP)-catalyzed dehydrogenative polymerization of S-alc was carried out in the presence of nucleophilic reagents that promote the rearomatization of S-QM. First, the HRP-catalyzed polymerization of sinapyl alcohol γ-O-β-D-glucopyranoside (isosyringin, iso-S), which allows us to monitor the polymerization process in a homogeneous aqueous phase, was utilized for screening of a nucleophile used as an S-QM scavenger. Monitoring of iso-S polymerization in the presence of various nucleophilic reagents by UV spectroscopy and gel permeation chromatography with photodiode array detection (GPC-PDA) revealed a high ability of azide ion to convert oligomeric S-QM efficiently to S-DHP. Accordingly, azide ion was utilized as an S-QM scavenger in HRP-catalyzed polymerization of S-alc, which resulted in high-yield production of S-DHPs (∼83%), as expected. The 1H-, 13C-, and 2D-HSQC NMR investigations on the resulting S-DHPs clearly demonstrated that azide ion efficiently performed nucleophilic additions to the C-α of S-QM during the polymerization. These results provide experimental proof that the low reactivity of S-QM with nucleophiles (such as water, phenolic, and aliphatic hydroxyl groups) in the conventional polymerization system critically impedes the production of S-DHPs from S-alc

Synthesis of (zinc(II) phthalocyanine)-containing cellulose derivative using phthalocyanine-ring formation reaction

2, 3-Di-O-myristyl-6-O-(zinc(II) phthalocyaninyl) cellulose (5) was synthesized from cellulose (1) by five reaction steps via 6-O-(3′, 4′-dicyanophenyl)-2, 3-di-O-myristyl cellulose (4). The key reaction was phthalocyanine-ring formation on a cellulose backbone, that is, the reaction of compound 4 with o-phthalodinitrile in the presence of hexamethyldisilazane and zinc acetate in DMF afforded to compound 5 in 35.4 % yield. Consequently, the degree of substitution with phthalocyanine moieties of compound 5 was 0.38. The LB monolayer film of compound 5 on an indium tin oxide (ITO) electrode was found to show photocurrent generation performance at 680 nm

Preparation of 6-azafulleroid-6-deoxy-2,3-di-O-myristoylcellulose.

6-Azafulleroid-6-deoxy-2, 3-di-O-myristoylcellulose (3) was synthesized from 6-azido-6-deoxycellulose (1) by two reaction steps. The myristoylation of compound 1 with myristoyl chloride/pyridine proceeded smoothly to give 6-azido-6-deoxy-2, 3-di-O-myristoylcellulose (2) in 97.0% yield. The reaction of compound 2 with fullerene (C_60) was carried out by microwave heating to afford compound 3 in high yield. It was found from FT-IR, [13]C NMR, UV-vis, differential pulse voltammetry (DPV), SEC analyses that compound 3 was the expected C_60-containing polymer. Consequently, maximum degree of substitution of C_60 (DS_{C60}) of compound 3 was 0.33