Gediminas Brazaitis

Species proportions by area in mixtures of Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.)

Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.) dominate many of the European forest stands. Also, mixtures of European beech and Scots pine more or less occur over all European countries, but have been scarcely investigated. The area occupied by each species is of high relevance, especially for growth evaluation and comparison of different species in mixed and monospecific stands. Thus, we studied different methods to describe species proportions and their definition as proportion by area. 25 triplets consisting of mixed and monospecific stands were established across Europe ranging from Lithuania to Spain in northern to southern direction and from Bulgaria to Belgium in eastern to western direction. On stand level, the conclusive method for estimating the species proportion as a fraction of the stand area relates the observed density (tree number or basal area) to its potential. This stand-level estimation makes use of the potential from comparable neighboring monospecific stands or from maximum density lines derived from other data, e.g. forest inventories or permanent observations plots. At tree level, the fraction of the stand area occupied by a species can be derived from the proportions of their crown projection area or of their leaf area. The estimates of the potentials obtained from neighboring monospecific stands, especially in older stands, were poorer than those from the maximum density line depending on the Martonne aridity index. Therefore, the stand-level method in combination with the Martonne aridity index for potential densities can be highly recommended. The species’ proportions estimated with this method are best approximated by the proportions of the species’ leaf areas. In forest practice, the most commonly applied method is an ocular estimation of the proportions by crown projection area. Even though the proportions of pine were calculated here by measuring crown projection areas in the field, we found this method to underestimate the proportion by 25% compared to the stand-level approach.

EuMIXFOR empirical forest mensuration and ring width data from pure and mixed stands of Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.) through Europe

Key messageThis data set provides unique empirical data from triplets of Scots pine (Pinus sylvestrisL.) and European beech (Fagus sylvaticaL.) across Europe. Dendrometric variables are provided for 32 triplets, 96 plots, 7555 treesand 4695 core samples. These data contribute to our understanding of mixed stand dynamics.Dataset access athttp://dx.doi.org/10.5061/dryad.8v04m. Associated metadata available athttps://metadata-afs.nancy.inra.fr/geonetwork/apps/georchestra/?uuid=b3e098ca-e681-4910-9099-0e25d3b4cd52&hl=eng.

Spontaneous Hybridization between Pinus mugo and Pinus sylvestris at the Lithuanian Seaside: A Morphological Survey

We address the problem of spontaneous hybridization between an exotic species Pinus mugo and the native/local P. sylvestris at the seaside spit of Kursiu Nerija in Lithuania. The objective was to identify spontaneous hybrids between P. mugo and P. sylvestris based on morphology traits among the individuals naturally regenerating at the seaside spit. The field inventory was carried out over the entire Lithuanian part of the spit, and 200 individuals morphologically intermediate between P. sylvestris and P. mugo were identified. Based on a weighted trait index, the intermediate individuals were grouped into two groups, one morphologically close to P. sylvestris and another close to P. mugo. The needle micromorphological traits of the putative hybrids were of intermediate values between P. mugo and P. sylvestris. The results provide a strong evidence of spontaneous hybridization between P. mugo and P. sylvestris in Lithuanian seaside spit of Kursiu Nerija.

DETECTION OF XENOBIOTIC SUBSTANCES IN MUTE SWANS’ (CYGNUS OLOR) BLOOD

During recent years the attention towards the effects of xenobiotic substances on wild nature has been steadily increasing. Literature reviews have revealed that active hormone-disintegrating substances might affect the reproduction of some wild animal species. Research shows anomalies of reproduction and development in various animal groups such as birds, fish, invertebrates and reptiles. Species inhabiting water and its surroundings cause the highest concern. Due to insufficient baseline information it is difficult to determine the extent of the problem in these wild populations on an ecological scale. The research described in this article is the first attempt to analyse xenobiotic substances and evaluate possible accumulation of pharmaceuticals in animals higher up in the food chain in Lithuania. This research tests new methods for to analyse for xenobiotics substances, which might be used in the future. Blood samples of 7 swans were examined using liquid chromatography, however, no xenobiotics were detected. Negative results do not eliminate the necessity for further investigate of larger samples, other species or to search for non-pharmaceutical xenobiotics. Keywords: mute swan (Cygnus olor), xenobiotics, compounds disintegrating the endocrine system, bioaccumulation, liquid chromatography. Article DOI: http://doi.org/10.15544/RD.2015.064