Wood logging generates considerable amounts of waste biomass (e.g. cones, bark, leaves, and roots), worthwile to use, as a potential source of antioxidants. Polyphenols represent an important type of non-enzymatic antioxidants in plants. Current data in scientific literature regarding the antioxidant content of coniferous cones and the antioxidant concentrations at different ripening stages is limited and have not been investigated in detail yet. Our investigation aimed to implement an ultrasonic extraction method for the assessment and comparison of the antioxidant polyphenol content of conifer cones: six arbitrarily selected taxa (Cedrus atlantica, Larix decidua, Picea abies, Pinus nigra, Pseudotsuga menziesii, Tsuga canadensis) commonly found in Hungary were investigated in the present study, which provides methodology for future investigations. The comparison of green, mature, and opened cones were carried out for each taxon. Folin-Ciocâlteu total phenol content, ferric reducing ability of plasma (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays were used to assess the antioxidant properties. The 30 min ultrasonic extraction using acetone:water 80:20 v/v solution resulted in the optimum yield on total polyphenols, FRAP, and DPPH. Best values were found for green cones, followed by mature, and opened cones for each species. Overall antioxidant power was determined by a scoring system that combined the three assay results. Taxa with the highest scores were Picea abies and Tsuga Canadensis, which contained high amounts of antioxidants in both green and mature cones and, surprisingly, also in opened cones (P. abies). Results provide a basis for future investigation and comparison involving a large number of taxa.

Wood logging generates considerable amounts of bark by-product, which are a potential antioxidant source well worth extracting and using. The present work compares the antioxidant properties of the bark of the following selected Hungarian forest tree species: white poplar (Populus alba L.), black locust (Robinia pseudoacacia L.), sessile oak (Quercus petraea Liebl.), black poplar (Populus nigra L.), silver birch (Betula pendula Roth), European larch (Larix decidua Mill.), scots pine (Pinus sylvestris L.), wild cherry (Prunus avium L.), European hornbeam (Carpinus betulus L.) and sweet chestnut (Castanea sativa Mill.). Inner and outer bark were investigated separately. Total polyphenol content (TPC) was determined by the Folin-Ciocâlteu method, whereas antioxidant capacity was assayed using the ferric reducing ability of plasma (FRAP), 2.2-diphenyl-1-picrylhydrazyl (DPPH), and ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) methods. The overall antioxidant power of the samples was evaluated using a scoring system that combined the FRAP, DPPH, and ABTS assay results. The TPC levels did not always follow the FRAP, DPPH, and ABTS assay values. Differing reaction mechanisms and sample compositions are possible reasons for this. The presented scoring evaluation was suitable for the assessment and comparison of complex antioxidant properties of tree bark samples. According to the scores, inner bark showed higher scores compared to outer bark for most species with the exceptions of black poplar, black locust, white poplar, sweet chestnut, and European larch. The highest overall antioxidant capacities were determined in the inner bark of wild cherry and the outer bark of sweet chestnut. The species with the overall lowest scores were black locust and black poplar.

Biogeosciences and Forestry Biogeosciences and ForestryTracing the acclimation of European beech (Fagus sylvatica L.) populations to climatic stress by analyzing the antioxidant system Eszter Visi-Rajczi (1) , Tamás Hofmann (1) , Levente Albert (1) , Csaba Mátyás (2) Through a common garden (provenance) experiment, we investigated the metabolic responses to climatic stress with regard to the acclimation potential of different European beech (Fagus sylvatica L.) populations. Selected enzymatic and non-enzymatic antioxidants were analyzed in leaves. Peroxidase (POD) and polyphenol oxidase (PPO) enzyme activity, total protein content as well as ABTS [2,2'-azino-bis-(3-etylbenzothiazoline)-6-sulphonic acid] antioxidant capacity were measured in the leaves of selected populations. Major leaf polyphenols were identified and their relative amounts were compared. Significant correlations were found between phenotypic (diameter growth) response to simulated climatic stress and the activity (and amount) of selected chemical components. The concentrations of certain polyphenols, POD enzyme activity, and total protein content may be chemical indicators of the acclimation potential of populations and may contribute to the forecasting of climate change effects, which can aid in the selection of suitable propagation material for adaptive silviculture.

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