Spruce Leaf Research Articles

Influence of Deposition Potential on Electrodeposited Bismuth–Copper Oxide Electrodes for Asymmetric Supercapacitor

AbstractThe modern research reported the simplest low–cost synthesis of Bismuth–Copper oxide (Bi2CuO4) with spruce–leaf–like morphology and its applications in supercapacitor devices. Bi (NO3)3 . 5H2O was used as a precursor during an electrodeposition (ED) method to create the spruce–leaf–like Bi2CuO4 electrode. XRD, XPS, FE−SEM, EDX, and TEM were used to characterize the structures and morphologies of the synthesized materials, while CV, CP, and EIS were used to determine their electrochemical characteristics. The Bi2CuO4 phase was confirmed by XRD patterns, and electrochemical testing demonstrated that the material had better rate capability and an SC of 431.2 F/g at a scan rate of 2 mV/s. After 5,000 cycles, it retained 81.4 % of its energy. Additionally, the maximum SC that was attained by the created asymmetric solid–state device ASSD (Bi0.6 Vǀǀ1 M PVA−KOHǀǀAC) was 73.7 F/g. The energy density was 55.3 Wh/Kg at a power density of 4570 W/Kg. The exceptional electrochemical performance of Bi2CuO4 thin film electrodes recommends it has a promising material.

3D meso-macroporous carbon derived spruce leaf biomass for excellent electrochemical symmetrical supercapacitor

3D meso-macroporous carbon derived spruce leaf biomass for excellent electrochemical symmetrical supercapacitor

Schrenk spruce leaf litter decomposition varies with snow depth in the Tianshan Mountains

Seasonal snowfall, a sensitive climate factor and the main form of precipitation in arid areas, is important for forest material circulation and surface processes and profoundly impacts litter decomposition and element turnover. However, how the thickness and duration of snow cover affect litter decomposition and element release remain unclear. Thus, to understand the effects of snow on litter decomposition, fiber degradation and their relationships with soil properties, a field litterbag experiment was conducted under no, thin, medium, and thick snow cover in a Schrenk spruce (Picea schrenkiana) forest gap in the Tianshan Mountains. The snow cover period exhibited markedly lower rates of decomposition than the snow-free period. The litter lignin, cellulose and N concentrations in the pregrowing season and middle growing season were significantly higher than those in the deep-freeze period, and the litter C and P concentrations were significantly higher during the onset of the freeze–thaw period, deep-freeze period and thaw period than in the late growing season. The litter cellulose, C and N concentrations were significantly higher under thick snow cover than under no snow cover in most stages. Moreover, the correlations among litter mass, cellulose, lignin/cellulose and soil bulk density varied with snow cover depth. The temporal variations and snow cover depth affected the decomposition process significantly. The former affected lignin, cellulose and P, and the latter affected cellulose, C and N and changed the litter-soil properties relationship. These differences provide references for understanding how winter conditions affect material cycling and other ecological processes under climate change.

Influence of gap position and competition control on the leaf physiology of planted Picea glauca and natural regeneration of Populus tremuloides

Maintaining white spruce (Picea glauca (Moench) Voss) in mixture with trembling aspen (Populus tremuloides Michx.) and other broadleaf competitors following timber harvest in boreal and sub-boreal mixed-wood stands is challenging. Under-planting spruce within harvest gaps is one potential strategy, but it’s unclear which gap environments favor spruce in relation to aspen. Here we test the effect of gap position and woody release treatment on leaf area development and growth physiology of spruce and aspen. Five positions were measured from the southern understory through the gap center to the northern understory in replicated strip cuts. The woody release treatment cut all stems around spruce including aspen in subplots within each experimental gap; other subplots were left un-cut for comparison. We measured leaf area per wet weight, leaf photosynthesis, stomatal conductance, and transpiration in low- and full-light conditions. We also assessed photosynthetic plasticity in relation to light. Overall, aspen maintained higher leaf area per unit wet weight than spruce, but spruce leaf area was more sensitive to changes in gap position. Aspen also maintained higher photosynthesis and transpiration rates than spruce under both light conditions, and woody release treatment. The magnitude of difference in gas exchange rates between the two species, however, depended significantly on woody release treatment and gap position for photosynthesis, and on gap position for transpiration. Photosynthetic plasticity was not significantly different across species, gap position, or woody release treatment. Our results indicate that in order to ensure the competitive advantage of spruce in mixed-wood boreal stands, forest managers should concentrate spruce planting and competition control efforts in the centers of canopy openings.

Fungal succession in relation to volatile organic compounds emissions from Scots pine and Norway spruce leaf litter-decomposing fungi

Leaf litter fungi are partly responsible for decomposition of dead material, nutrient mobilization and gas fluxes in forest ecosystems. It can be assumed that microbial destruction of dead plant materials is an important source of volatile organic compounds (VOCs) emitted into the atmosphere from terrestrial ecosystems. However, little information is available on both the composition of fungal VOCs and their producers whose community can be changed at different stages of litter decomposition. The fungal community succession was investigated in a litter bag experiment with Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) needle litter. The succession process can be divided into a several stages controlled mostly by changes in litter quality. At the very first stages of decomposition the needle litter was colonized by ascomycetes which can use readily available carbohydrates. At the later stages, the predominance of Trichoderma sp., the known producers of cellulolytic enzymes, was documented. To investigate the fungi-derived VOCs, eight fungi species were isolated. As a result of gas chromatographic analyses, as many as 75C2C15 fungal volatile compounds were identified. Most components detected in emissions were very reactive substances: the principal groups of VOCs were formed by monoterpenes, carbonyl compounds and aliphatic alcohols. It was found that production of VOCs by fungi is species specific: only 10 metabolites were emitted into the gas phase by all eight species. The reported data confirm that the leave litter decomposition is important source of reactive organic compounds under the forest canopy.

Retrieval of spruce leaf chlorophyll content from airborne image data using continuum removal and radiative transfer

We investigate combined continuum removal and radiative transfer (RT) modeling to retrieve leaf chlorophyll a & b content (Cab) from the AISA Eagle airborne imaging spectrometer data of sub-meter (0.4 m) spatial resolution. Based on coupled PROSPECT-DART RT simulations of a Norway spruce (Picea abies (L.) Karst.) stand, we propose a new Cab sensitive index located between 650 and 720nm and termed ANCB650–720. The performance of ANCB650–720 was validated against ground-measured Cab of ten spruce crowns and compared with Cab estimated by a conventional artificial neural network (ANN) trained with continuum removed RT simulations and also by three previously published chlorophyll optical indices: normalized difference between reflectance at 925 and 710nm (ND925&710), simple reflectance ratio between 750 and 710nm (SR750/710) and the ratio of TCARI/OSAVI indices. Although all retrieval methods produced visually comparable Cab spatial patterns, the ground validation revealed that the ANCB650–720 and ANN retrievals are more accurate than the other three chlorophyll indices (R2=0.72 for both methods). ANCB650–720 estimated Cab with an RMSE=2.27μgcm−2 (relative RRMSE=4.35%) and ANN with an RMSE=2.18μgcm−2 (RRMSE=4.18%), while SR750/710 with an RMSE=4.16μgcm−2 (RRMSE=7.97%), ND925&710 with an RMSE=9.07μgcm−2 (RRMSE=17.38%) and TCARI/OSAVI with an RMSE=12.30μgcm−2 (RRMSE=23.56%). Also the systematic RMSES was lower than the unsystematic one only for the ANCB650–720 and ANN retrievals. Our results indicate that the newly proposed index can provide the same accuracy as ANN except for Cab values below 30μgcm−2, which are slightly overestimated (RMSE=2.42μgcm−2). The computationally efficient ANCB650–720 retrieval provides accurate high spatial resolution airborne Cab maps, considerable as a suitable reference data for validating satellite-based Cab products.

Chemical composition of volatile and extractive compounds of pine and spruce leaf litter in the initial stages of decomposition

Abstract. A litter bag experiment was conducted to analyze changes in chemical composition in Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) needle litter in the first stages of decomposition in natural conditions. The emission rates of monoterpenes and concentration of extractive secondary metabolites were determined five times over a 16-month period. It has been shown that pine and spruce needle litter in the first stages of decomposition (up to 165 days) emits monoterpene hydrocarbons into the gas phase with the rates comparable to those in emissions from live needles of these trees. This suggests that leaf litter is an important source of atmospheric terpenes. It has also been proved that the litter contains considerable amounts of non-volatile substances that can be precursors of oxidized volatile compounds formed as a result of enzymatic reactions. Non-volatile but water soluble secondary metabolites of the leaf litter may be involved in nutrient cycling and have an influence on soil community.

The effect of long term CO2 enrichment on the growth, biomass partitioning and mineral nutrition of Sitka spruce (Picea sitchensis (Bong.) Carr.)

Sitka spruce [Picea sitchensis (Bong.) Carr.] seedlings were grown for 3 years in an outside control plot or in ambient (∼355 μmol mol-1) or elevated (ambient + 350 μmol mol-1) atmospheric CO2 environments, within open top chambers (OTCs) at the Institute of Terrestrial Ecology, Edinburgh. Sequential harvests were carried out at the end of each growing season and throughout the 1991 growing season, five in all. Plants grown in elevated CO2 had, (i) 35 and 10% larger root/shoot ratios at the end of the first and third season, respectively, (ii) significantly higher summer leader extension relative growth rates, which declined more rapidly in early autumn than ambient grown plants, (iii) after three growing seasons a significantly increased mean annual relative growth rate, (iv) consistently lower foliar nutrient concentrations, and (v) after two growing seasons smaller total projected needle areas. Plants grown inside OTCs were taller, heavier and had a smaller root/shoot ratio than those grown outside the chambers. There was no effect of CO2 concentration on Sitka spruce leaf characteristics, although leaf area ratio, specific leaf area and leaf weight ratio all fell throughout the course of the 3 year experiment.

Statistical error analysis for biomass density and leaf area index estimation

Dimension analysis uses fitted allometric relationships to estimate whole-tree characteristics from dimensional measurements. Errors in dimension-analysis estimates of forest stand biomass and leaf area are often unreported and rarely analyzed. Errors may arise from measurement error, choice of model, fitting of parameters in models, and spatial variation within a sampled stand. Examination of these components separately will show how efficiency can be most effectively increased and balanced. We used dimension analysis to estimate biomass density and leaf area index for stands of trembling aspen (Populustremuloides Michx.) and black spruce (Piceamariana (Mill.) B.S.P.) in the Superior National Forest, Minnesota, United States. Estimates had average coefficients of variation ranging from 11% (aspen biomass density) to 23% (spruce leaf area index). Partitioning of these errors showed that error sources varied with species, variable, and site conditions, but most error was due either to parameter estimation or to spatial variation; model inaccuracies contributed only trivially to total error. The most cost-effective means of increasing precision of estimation would be to sacrifice more trees (even with less precise measurements of individual trees) to fit the models, or sample larger areas in stands; more sophisticated models would have little effect on error.

CHEMOSYSTEMATIC STUDIES IN THE GENUS PICEA (PINACEAE): II. THE LEAF OIL OF PICEA GLAUCA AND P. MARIANA

The leaf oils from white and black spruce obtained from different locations in Western and Eastern Canada, Michigan, and Minnesota, have been analyzed by gas liquid chromatography. Both species were found to have a remarkably consistent and distinctive distribution pattern of the leaf oil terpenes. The quantitative variations encountered in samples of the same species from different populations are relatively small and ecological differences are not found to affect the leaf oil composition. Hence, analysis of spruce leaf oils appears to be highly suitable for a study of introgression and hybridization.

The chemical composition of the volatile oil of the leaves of Picea rubens Sarg. and chemotaxonomic correlations with other North American spruce species : Gas-liquid chromatography of terpenes—XIV.

The volatile oil from two populations of red spruce was found to consist mainly of bornyl acetate (55 per cent). Smaller amounts of α- and β-pinene, camphene, 3-carene, myrcene, limonene, α- and β-phellandrene, p-cymene, 1:8-cineole, linalool, camphor, terpinen-4-ol, α-terpineol, borneol, piperitone, citronellyl and geranyl acetate, bisabolene and a mixture of γ- and δ-cadinene (“canadene”) were also isolated. Santene, tricyclene, γ-terpinene, thujone, isothujone and isoborneol were tentatively identified. The leaf oils of the foliage from black spruce (2 trees) white spruce (3 trees) and Colorado spruce (5 trees) were analysed by GLC and the data obtained were compared with those of red spruce. The close phylogenetic relationship of red and black spruce was found to be reflected in the chemical composition of their leaf oils, whereas significant chemical differences were observed with both white and Colorado spruce. Hypothetical pathways for the formation of the terpenes found in spruce leaf oils from a single precursor, such as geranyl pyrophosphate, are discussed. Piperitone, a C-3 oxygenated monoterpene, appears to take an exceptional position in such postulated sequences. Also, not all of the compounds expected from schemes involving carbonium-ion intermediates are found in the spruce leaf oils.

GAS–LIQUID CHROMATOGRAPHY OF TERPENES: PART X. THE VOLATILE OILS OF THE LEAVES OF SITKA AND ENGELMANN SPRUCE

The leaf oils from Sitka and Engelmann spruce were obtained in 0.36 and 0.094% yield respectively. The average percentage composition was determined by gas–liquid chromatography. Sitka spruce leaf oil was found to contain mainly d-myrcene (23.5%), l-piperitone (23.2%), and d-camphor (17.2%). Smaller amounts of 1,8-cineole, l-β-phellandrene, p-cymene, two aliphatic esters, d-bornyl acetate, d-borneol, and d-terpinen-4-ol were also isolated and several other esters appeared to be present in small amounts. Engelmann spruce leaf oil was found to contain mainly cis-hex-3-en-1-ol (18.5%), d-camphor (16.0%), d-bornyl acetate (8.6%), d-linalool (5.8%), and two unidentified compounds. Smaller amounts of myrcene, β-phellandrene, p-cymene, piperitone, and several sesquiterpenoids were also recorded. Tricyclene, α-pinene, camphene, β-pinene, 3-carene, limonene, γ-terpinene, and terpinolene were found in small amounts in both oils.Phylogenetic relationships between the different spruces and other conifers are discussed.