Changes in elm (Ulmus) populations of mid-westernPolandduringthepast35years

Abstract: Three elm species are native to Poland: wych elm (Scots elm) (Ulmus glabra Huds.), field elm (U. minor Mill.), and European white elm (fluttering elm) (U. laevis Pall.). The epidemic of Dutch elm disease (DED) has led to a decrease in the popularity of elm cultivation. An analysis of forestry data was the first step in the assessment of elm resources. The area of forest stands where elms are dominant has more than doubled since 1978. Lowland alluvial forests rank first in regards to the number of elm localities per unit area of a given forest site type. While this site type is clearly preferred by elms, the majority of elm trees are actually scattered among sites of oak-hornbeam or closely related forests (of the alliance Carpinion betuli). Field research revealed a clear dominance of U. laevis, a species which in the past was predominantly located out of woodland and rarely cultivated. Data analysis indicated that all trees greater than 70 cm in diameter belonged to this species. Data from plots surveyed directly also suggest that the three elm species have slightly different habitat preferences. U. laevis prefers riparian habitats, although the major part of its resources is now on potential sites of oak-hornbeam or closely related forests. U. minor even more often than U. laevis occurs at less humid sites (mostly potential sites of oak-hornbeam or closely related forests), while U. glabra prefers moist slopes. In general, it appears that the impact of DED in the last 20-30 years has been smaller than in the preceding period, however, the disappearance of the disease has not been established. Undoubtedly, U. laevis is the elm species that is least impacted by DED

Effect of pre-planting soil preparation on biological activity of soil towards root rot pathogens in 40-year-old Scots pine stand

Effects of pre−planting soil preparation on the clear−cut on the community structure of soil fungi and bacteria, their possible biological activity towards Armillaria and Heterobasidion, and mortality of Scots pine trees were studied in 40−year−old Scots pine plantation in Międzychód Forest District (W Poland). Pre−planting soil preparation included: (i) deep ploughing, (ii) shallow furrowing, (iii) making holes for planting, and (iv) shallow turning of the topsoil. The soil−dilution method was used for detection of fungi and bacteria in soil. Morphotyping was used for identification of fungi. Phenotypic traits and biochemical properties were used for identification of bacteria. Molecular method, MID−66 or BIOLOG® systems were additionally applied for identification of the most common bacteria. Deep furrowing, making holes for planting or shallow turning of the topsoil before planting increased abundance of fungi and bacteria in soil 40 years after treatment. Increased abundance of fungi and bacteria was associated with increased presence of taxa considered as antagonistic to Armillaria and Heterobasidion. The highest mortality of Scots pines was observed on sites with deep ploughing or shallow furrowing before planting, while the lowest mortality was found on sites with making holes for planting or shallow turning of the topsoil. The majority of dead trees were infected by H. annosum. Moderate intervention into the soil habitat on the clear−cut site before planting of Scots pine seedlings seems to create the habitat beneficial for the future growth of trees

Communities of fungi in decomposed wood of oak and pine

The abundance and diversity of wood decomposing fungi were investigated by isolating and cultivating filamentous fungi from wood and by detection of fruit bodies of ascomycetous and basidiomycetous fungi. The objective was to study the impact of forest management on fungi in 100-year-old oak and 87-year-old Scots pine forests in Northern Poland. Fungi were found on coarse woody debris of decayed stumps and fallen logs, boughs and branches in each of the three (managed and unmanaged) examined stands. In total, 226 species of Oomycota and fungi were recorded. Oak wood was colonized by one species of Oomycota and 141 species of fungi including Zygomycota (19 species), Ascomycota (103 species) and Basidiomycota (19 species). Scots pine wood was also colonized by one species of Oomycota and 138 species of fungi including Zygomycota (19 species), Ascomycota (90 species) and Basidiomycota (29 species). In the first, second and third stages of decomposition, the oak wood was colonized by 101, 89 and 56 species of fungi respectively and pine wood was colonized by 82, 103 and 47 species respectively. Eighty three of the observed species (37%) occurred on both types of wood, while the other species displayed nutritional preferences. A decrease in the number of species with advancing decay indicates the necessity for a continuous supply of dead wood to the forest ecosystem. This supply would secure the continuity of fauna and flora and guarantee a stable forest development. The nutritional and ecological preferences of many fungal species furthermore indicate the necessity of supplying the forests with wood of different species. In commercially managed forests the results obtained here will aid in: (i) the development of strategies for effective dead wood management in the context of forest productivity and future wood stock growth, as well as (ii) finding a compromise between forest management requirements and environmental protection

SUR LE MINIMUM DE LA SECTION EFFICACE TOTALE DANS LA RÉGION DES NOYAUX ATOMIQUES AVEC A = 60 POUR DES PARTICULES ALPHA DE 24,7 MeV

La section efficace totale pour l'interaction des particules alpha à l'énergie 24,7 MeV avec les noyaux atomiques de Cr, Fe, Ni, Co, Cu et Zn a été mesurée à l'aide de la méthode de transmission. Les corrections aux résultats des mesures de la transmission pour la diffusion élastique et pour les particules chargées issues des réactions étaient déterminées dans les expériences effectuées spécialement. Les résultats pour les sections efficaces totales des réactions sont en accord avec les calculs faits à l'aide du modèle optique. Aucun minimum dans la courbe représentant les valeurs σR vers A n'a été observé pour les noyaux atomiques de nickel.The total reaction cross-section for the interaction of alpha particles of the energy of 24.7 MeV with Cr, Fe, Ni, Co, Cu, and Zn nuclei has been measured by means of the transmission method. The corrections to the transmission measurements for the elastic scattering and for the charged products of reactions have been determined from a specially performed experiment. The results for the total reaction cross-sections are in agreement with optical model calculations. No minimum in the σR versus A curve for the nickel atomic mass-numbers is observed

The Influence of Annealing Temperature on Magnetic Properties of Vitrovac 6030

Co-Fe-Mo-Mn-Si-B metallic glass ribbon (Vitrovac 6030) was subjected to the isothermal annealing at temperatures in the range 523-873 K so as to produce a series of samples with gradually coarser microstructure. For this series of samples a giant increase in the coercivity, exceeding three orders of magnitude, is observed. This increase is interpreted in terms of the strengthening of the pinning effect of the nanocrystalline structure on the moving domain walls. It is shown that the anisotropy of the created crystallites is mainly responsible for the increase in the pinning force since the effective anisotropy seen by the wall becomes larger and larger with the gradual increase in the density and size of the grown particles