Timing of resin-tapping operations in maritime pine forests in Northern Spain

Aim of study: To optimize the timing of resin-tapping activities for maximizing the economic efficiency of resin tapping in Atlantic maritime pine forests. Area of study: Northern Spain. Material and methods: We conducted three small experiments in a mature maritime pine forest aimed to test: i) the impact of groove frequency on resin production, ii) the effect of previous grooves as a driver of temporal patterns of resin production along the seasons and iii) the impact of previous tapping on resin production in the following campaign. Main results: The resin produced decreased as groove frequency decreased, but the reduction was low. Considering that the number of trees that a worker can tap increases with more spaced grooves, higher tapping efficiency can be achieved with monthly grooves. Previous tapping increased resin yield during the following campaign but resin production was not affected by the previous grooves during the current tapping campaign. Research highlights: Responses to wounding seem to require time to be effective and temporal patterns of resin production appear to be driven by weather conditions alone.

Pycnogenol - extract from French maritime pine bark (Pinus pinaster), as an effective antioxidant against superoxide radical

Background: Interest in the positive impact of naturally occurring polyphenols is still increasing in the scientific community. Research is focused mainly on their antioxidant properties, due to their significant effects in the prevention of diseases associated with oxidative stress. Pycnogenol is an extract from French maritime pine bark (Pinus pinaster), which is composed of a mixture of phenolic compounds: monomers (catechin, epicatechin, taxifolin), flavonoids (classed as procyanidins/proanthocyanidins), phenolic or cinnamic acids and their glycosides. Due to its composition, it has a high antioxidant capacity, and is used in traditional folk medicine, cosmetics and medicine.Purpose of the study: The aim is to study the antioxidant properties of pycnogenol in order to obtain experimental information on the antioxidant effect of pycnogenol in terms of concentration dependence and pH conditions.Methods: In our study, we used a methionine-riboflavin superoxide generator, and focused on determining the antioxidant capacity of Pycnogenol against the superoxide radical in different pH values (range 6.5 – 8) using the spectroscopic method.Results: Our results showed that the antioxidant properties increased with a higher concentration of the tested compound in the tested pH range. Amongst all tested pH values, the most appropriate for pycnogenol antioxidant capacity is slightly basic pH (pH 8).Conclusion: Information on the antioxidant and prooxidant properties of naturally occurring compounds is very important for understanding their activity and their proper use in prevention, disease treatment, and detection of pathological processes. The antioxidant activity of pycnogenol depends on the structure and concentration of antioxidants; it only slightly changes at different pH values. Increasing concentration of pycnogenol enhances its antioxidant properties.Keywords: Pycnogenol, reactive oxygen species, spectrophotometry, pH dependency

Extreme climatic events but not environmental heterogeneity shape within-population genetic variation in maritime pine

How evolutionary forces interact to maintain quantitative genetic variation within populations has been a matter of extensive theoretical debates. While mutation and migration increase genetic variation, natural selection and genetic drift are expected to deplete it. To date, levels of genetic variation observed in natural populations are hard to predict without accounting for other processes, such as balancing selection in heterogeneous environments. We aimed to empirically test three hypotheses: (i) admixed populations have higher quantitative genetic variation due to introgression from other gene pools, (ii) quantitative genetic variation is lower in populations from harsher environments (i.e. experiencing stronger selection), and (iii) quantitative genetic variation is higher in populations from spatially heterogeneous environments. We used phenotypic measurements of five growth, phenological and functional traits from three clonal common gardens, consisting of 523 clones from 33 populations of maritime pine (Pinus pinaster Aiton). Populations from harsher climates (mainly colder areas) showed lower genetic variation for height in the three common gardens. Surprisingly, we did not find any association between within-population genetic variation and environmental heterogeneity or population admixture for any trait. Our results suggest a predominant role of natural selection in driving within-population genetic variation, and therefore indirectly their adaptive potential.

Homogenization of Maritime Pine Wood Color by Alkaline Hydrogen Peroxide Treatment

The color of maritime pine wood is a critical parameter for manufacturing high added value materials (wood flooring or wood paneling for indoor applications). Actually, the color inhomogeneity between heartwood (Hw) and sapwood (Sw) can lead to a depreciation of the wood value and, therefore, to financial losses for wood products companies. In this article, the development of a color homogenization process based on alkaline hydrogen peroxide chemistry was studied. Maritime pine heartwood and sapwood powders were used to facilitate the chemical characterizations and colorimetric analyses by the CIEL*a*b* system. Brighter materials were obtained after the treatment by reducing significantly the color difference. The chemical modifications of wood surface were characterized by infrared spectroscopy analyses. The color evolution of the material overtime was also studied thanks to an accelerated ageing under UV irradiation. It was demonstrated that even if a color reversion occurred by oxidation, the color remained homogeneous between heartwood and sapwood.