Marisia - Maros Megyei Múzeum Évkönyve 31/2. (2011)
Botany
Silvia OROIAN, Mihaela SÄMÄRGHITAN ____________1__________________2___ classification papers at European level [11] and also on synthetic works developed on the vegetation of Romania [7,8,14]. Results and discussions The deforestation of oak and hornbeam trees in Transylvania has led to the settlement of mesophilic and xerophilic phytocoenoses in the Transylvanian Plain. Two plant associations have been identified in the studied area: MOLINIO-ARRHENATHERETEA R. Tx. 1937 em. R.Tx. 1970 ARRHENATHERETALIA R. Tx. 1931 ARRHENATHERION Koch 1926 Arrhenatheretum elatioris Br.-Bl. ex Scherrer 1925 FESTUCO - BROMETEA Br.-Bl. et R.Tx. ex Klika et Hadac 1944 BROMETALIA ERECTI Br.-Bl. 1936 CIRSIO-BRACHYPODION PINNATI Hadac et Klika in Klika et Hadac 1944 Thymo pannoniéi — Stipetum stenophyllae Sanda et al 1998 (Syn. Stipetum stenophyllae transsilvanicum Sod 1946 apud Soó 1947) 1. Ass. Arrhenatheretum elatioris Br.-Bl. Ex Scherrer 1925 The association Arr'henatheretum elatioris Br.-Bl. Ex Scherrer 1925 (Table 1) is found on a hillside at the altitude of 400 m s.m, with eastern exposure and a 40° slope, in the potential area of the oak and hornbeam forest, a grass edge formed by Dictamnus albus, Vincetoxicum hirundinaria, Euphorbia epithymoides and xerothermal vegetation islands. It is a secondary association with a heterogeneous floristic composition. Coenoses have a very good vegetation coverage (100%), with a continuous and dense plant canopy. Along with the two dominant species, Arrhenatherum elatius and Pastinaca sativa, many species of the Arrhenatheretalia order are found: Agrostis capillaris, Dactylis glomerata, Galium mollugo, Leucanthemum vulgare. The study of the humidity requirements of the species shows that the majority of the species are xero-mesophilic and, consequently, leave their mark on the character of the flora, which has moderate humidity requirements. These are followed by mesophilic and xerophilic species. Regarding the behavior of plants in relation to temperature, the temperate climate determines the predominance of micro-mesothermal elements, followed by moderately thermophilic species. Eurythermal species are present in a significant proportion. From the point of view of edaphic preferences, of the soil reaction, weakly acid-neutrophilic species have the highest proportion, followed by euryionic species. These euryionic species cannot characterize certain stations, but they participate in the creation of the ecological and coenotic environment of the plant groups. The acid-neutrophilic species are in accordance with the distribution of the types of soil in the studied area and with the frequent levigation phenomena of the hillside soils. Neutro-basophilic species also appear on the hillside (Fig. 1). The analysis of biological forms is an important element in the characterization of the association, evidencing some features of the biotopes and the influence of various factors on these. The percentage distribution of the bioforms is shown by the spectrum of bioforms (Fig. 2). The high percentage of hemicryptophytes indicates that the studied area belongs to the temperate climate areas. The presence of therophytes indicates a more arid climate and a high degree of anthropic influence. 10
