The past, present and future tasks of Hungarian dendrological research.
Hungarian dendrological research (research of living woody plants) has more than 200 years old history; the first general work by János Keresztély Grossinger was published in 1797. Further basic works in our time yet are: Forest Botany by Lajos Fekete and Sándor Mágócsy-Dietz (1896); and the chorological work, Distribution of trees and shrubs of sylvicultural importance in the region of Hungarian State by Lajos Fekete and Tibor Blattny (1913). A few dendrologists and many botanists have helped to get better knowledge of Hungarian dendroflora. From the point of view of taxonomy, chorology and habitat - which are interested by field botanists - it can be said that knowledge is fairly heterogeneous. There are sufficient information about most of the rare (protected/endangered) woody plants (an about 50 species) and the important adventives, above all invasive trees and shrubs (an about 10 species). From these two groups beyond there are only few taxa which can be said thoroughly worked up and known (e.g. Castanea sativa, Cornus mas, Fraxinus spp., Quercus spp.). List of the dendrotaxa, hardly known in the above-mentioned point of view is rich in species that are important for forestry or horticulture (e.g. Alnus glutinosa, Acer spp., Betula pendula, Corylusavellana and most of Salix spp.), supplemented with other species (e.g. Clematis vitalba, Colutea arborescens, Lonicera xylosteum, Padus avium, Sambucus nigra, Staphylea pinnata, Viburnum spp.).Followings can be asked from our field botanists: i) look for a specialist in cases of critical dendrotaxa; ii) a circumspect identification is necessary - especially in the case of leaves - by right of great number of samples from the adequate part of shoot; iii) keep in view frequent hybridization (e.g. in the case of Betula, Crataegus, Pyrus, Tilia), and frequent appearance of hybrids (e.g. Betula × rhombifolia, Cerasus × eminens, Salix × rubens); iv) appearance of interim forms are usually typical in the cases of species classified into aggregate species (e.g. Quercus petraea agg., Qu. pubescens agg.); v) take intraspecific taxa according to various ecological demands, area, morphological differences into consideration; vi) culture variations cannot be treat as an equal with the species (e.g. Populus spp., Salix spp.); vii) natural ↔ artificial area have to be separated; viii) lend a helping hand in getting taxonomical knowledge of hardly known dendrotaxa.
Adaptive genetic variability and differentiation of Croatian and Austrian Quercus robur L. populations at a drought prone field trial
Provenance trials, where populations of different geographical origin are tested in a common environment (common garden test), are a tool suited to allow the study of intraspecific adaptive genetic variation. Research of pedunculate oak (Quercus robur L.) adaptive genetic variability through analyses of populations in common garden tests has a long tradition. However, pedunculated oak populations originating south-eastern from the Alps have been scarcely studied in this way. This study addresses the adaptive genetic variability and differentiation of pedunculate oak populations originating from Austria and Croatia in a provenance/progeny field trial. Studied plants were six years old and were growing at the trial for three years. After two years of unusually low precipitations height and survival were analysed. The total mean height of all plants in the trial was 137.8 cm and ranged from 123.0 cm to 151.8 cm. The overall mean survival rate was rather high (0.85). Mean population survival ranged from 0.64 to 0.94. Individual narrow-sense heritabilities (hi2), family mean heritabilities (hf2), the coefficients of additive genetic variation (CVA) and quantitative genetic differentiation coefficients (QST) were calculated. A multivariate regression tree (MRT) analysis was used to determine the pattern of genetic differentiation of the populations. Individual heritabilities for height ranged between 0.00 and 0.39. Family mean heritabilities for height were rather low in most populations as well (<0.5). Family mean heritabilities for survival were higher than for height (ranging between 0.00 and 0.77). Calculated QST coefficients (0.25 for height and 0.14 for survival) indicated between-population genetic differentiation. The populations were separated into two clusters by MRT analysis regarding a climatic variable, namely Hargreaves’ reference evapotranspiration. Populations originating from comparatively more humid habitats were grouped in the first cluster. The first cluster had a lower mean height and survival compared to the second one. The differences between these clusters were highly statistically significant. The observed quantitative genetic differentiation might have been driven by natural selection caused by differences in the relative moisture of the habitats from which the progeny populations originate. The results suggest ecotypic pattern of the quantitative genetic differentiation among studied populations.
Variability of leaf growth characteristics in the canopy of sessile oak and Austrian oak
In this study the variability of leaf growth traits was investigated within the canopy of the two dominant tree species of Quercetum petraeae-cerris forest community, covering 30 % of the present forested area in Hungary. The investigation were performed in the “Sikfôkut Project” LTER site (Jakucs 1985). We compared the present leaf growth traits of species with those reported by Virágh (1985) for years of 1973-1975 before the decline of sessile oak in the site. After bud break leaves of the two canopy layers exhibited different rate in the increase of leaf area (La) and leaf mass (Lm). In spring shade leaves showed more intense increase in leaf area than in leaf mass. This resulted in a transitional large reduction of SLM in the shade leaves. In case of sessile oak the full leaf size was achieved within the same period in 2003 and 2004 but the area of mature leaves were larger in both canopy layers in 2004 than in 2003. In case of sessile oak the area of mature leaves in growing seasons of 2003 and 2004 increased significantly as compared to the period before the forest decline (Virágh 1985). In the upper canopy layer of Austrian oak the leaf area and leaf mass did not differ significantly from those reported for the period before the forest decline. In the lower layer of the canopy, however, the increase of leaf area was observed but the leaf mass exhibited similar values. In 2004 the loss of leaf area in the sun layer was 17% and in the shade layer 6 % as a consequnce of photophagous damages. In case of Austrian oak the loss of leaf area was smaller and amounted only to 1-5%. Acta Biol Szeged 49(1-2):149-150 (2005)