Szekessy Vilmos (szerk.): A Magyar Természettudományi Múzeum évkönyve 62. (Budapest 1970)

Kováts, D.: Quantitative xylotomic investigations on the xylem of our home ash trees

ANNALES HISTORICO-NATURALES MUSEI NATIONALIS HUNGARICI Tomus 62. PARS BOTANICA 1970. Quantitative Xylotomic Investigations on the Xylem of our Home Ash Trees By D. KOVÁTS, Budapest The importance of and the ever increasing demand for industrial woods necessitate—today more than ever—their knowledge not only from the standpoint of forestry and industry but also from biological points of view. The intensive and planned investigation of the xylotomic properties of trees is indispensable for a safe basis to evaluate the several species in the diverse branches of industry. The European Ash (Fraxinus excelsior L.) is a hardwood well utilisable in industry, it can be easily processed, split, steamed, and bent. It can be well applied wherever great solidity is required, it is highly wear-resistant, and tolerates shocks and pressures excellently. It is extensively used in furniture industry, in the manufacture of transport vehicles, as tool timber in agricultural machines, and in several other fields of use. • The aim of the present paper is a comparison of the anatomical conditions and the measuring of their changes by quantitative xylotomic methods of our two most important home ash species (Fraxinus excelsior L., and F. ornus L.), with due consideration of the diverse locality conditions. To make comparisons and generalizations possible, I worked up a material gathered from 5 different localities (sample disks of 3 Fraxinus excelsior and of 2 Fraxinus ornus trees). The main data of the trees are submitted in the Table. (The research material was made available by the Institute of Applied Botany and Histogenesis.) Macerations were made with SCHULZENS mixture, and the material softened in autoclaves for the preparation of slides; malachitgreen-vesuvin double-staining was used (SÁRKÁNY, 1957, 1964). Growth ring width was measured by an MBS-2 type stereo-binocular microscope, with a measuring ocular, for all growth rings on both the tension and pression sides. Fibre length measurements were made from each fifth growth ring, mainly in macerates but also in tangential longitudinal sections. Medullary ray percentages were established in cross-sections in a single long tangential line in middle wood, also for each fifth growth ring. A LEiTz-type object-table integrator with magnification 120 was used (STIEBER, 1960). In cross-sections, the examined trees proved to have a concentric structure, not precluded by the many counter-decurrences (accessory graphs of Figs. 6-10). With regard to all growth rings, the growth ring width of the pression side exceeds only slightly that of the tension side. Owing to the rather considerable concentricity, I did not measure fibre length and medullary ray percentage separately in the tension and pression woods, but in the middle wood. According to the investigations of SZÁLAI and VARGA (1956), growth ring width decreases outwards in the wood in a closed stand, considerably influenced by enviromnetal effects. This is expressed in poresring width and late wood. The above authors state that growth ring width decreases in the upward direction. My research disks originate from a height of 1-2 m, hence from largely the same level. I found a certain fluctuation in the evolvement of growth ring width, according to the given year, in both tension and pression woods (Figs. 1, 2). Contrarily to the