DIGITALNA ARHIVA ŠUMARSKOG LISTA
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| ŠUMARSKI LIST 3-4/2015 str. 51 <-- 51 --> PDF |
(Φ = 0.66), Fraxinus pennsylvanica Marshall (Φ = 0.63), Solanum dulcamara (Φ = 0.55), Polygonum hydropiper L. (Φ = 0.45). Diagnosis: Ass. Carici otrubae–Fraxinetum pennsylvanicae is developed on marshy, gley (eugley), hypogley, saline soils, on altitudes between 73 - 78 m on a flat surface, up to 5° inclination. Dominant species Fraxinus pennsylvanica can reach height up to 10 m in the canopy layer, while younger individuals are present also in the lower layers. Total cover varies from 80 to 100 %, averaging about 95 %. Total of 57 taxa are present in all 11 relevés. The average number of species per stand is 14. Since Fraxinus pennsylvanica, the dominant and nominal species is invasive, the association has an invasive character itself. The fact that individuals of the dominant invasive species are present in shrub and herb layers, indicate that this community is in progradation, and the final stage will result in the development of monodominant forest, as well as the first association. The other invasive species present in this association are the following: Acer negundo, Amorpha fruticosa, Aster lanceolatus Willd., Bidens frondosa, Celtis occidentalis L. and Gleditsia triacanthos. Ecology and synchorology of associations – Ekologija i sinhorologija asocijacija Stands of new associations Rubo caesii–Aceretum negundi and Carici otrubae–Fraxinetum pennsylvanicae are so far known only from the investigated area, on the former floodplain of Carska bara in northeastern Serbia. There are typical alluvial landforms, both natural and anthropogenically conditioned, due to frequent man interventions. The geological structure is dominated by sediments of Neogene age and pedological structure by alluvial saline soil and gleys, marshy black soil and smonitsa and solonchak´s solonetz. Mean annual temperature is 11.6 °C. The coldest month is January with the mean monthly temperature of 0.1 °C, while August is the hottest month with the mean temperature of 22 °C. The mean temperature of winter months is above zero, which is regularly the case in recent years. The average of annual rainfall is 609.8 mm. In the vegetation period (April – October), mean annual amount of precipitation is 68.0 mm in the monthly average. The potential steppe and forest-steppe vegetation (alliances Festucion rupicolae Soó 1940, and Aceri tatarici–Quercion Zólyomi et Jakucs 1957) are determined by these climatic conditions and geographic location of the wider surrounding area. The potential vegetation in the riparian zone of this area is presented by the azonal vegetation of hygrophile flooded forests of the alliances Salicion albae Soó 1940 (EUNIS G1.1) and Fraxinion angustifoliae Pedrotti 1970 (EUNIS G1.2) (Davies et al., 2004). However, the natural vegetation has been greatly disturbed, providing the space for the establishment and spread of invasive plant communities. Syntaxonomical scheme – Sintaksonomska shema Class Robinietea Jurko 1963 ex Hadač et Sofron 1980 Order Chelidonio–Robinietalia Jurko ex Hadač et Sofron 1980 Alliance non defined Ass. Rubo caesii–Aceretum negundi Batanjski et S. Jovanović ass. nova hoc loco Ass. Carici otrubae–Fraxinetum pennsylvanicae Batanjski et S. Jovanović ass. nova hoc loco Discussion Rasprava According to Stojšić (2010), the most common forest community in the riparian habitats of the investigated area is Salicetum albae pannonicum Parabućski (1965) 1972. There are also Populetum nigro–albae Slavnić 1952 and the fragmented communities Fraxino–Quercetum roboris Rudski (1940) 1949. The native riparian forest vegetation was under strong anthropogenic pressure (before it was protected), which resulted both in occurrence and the spreading of the invasive species, especially woody ones. Negative direction of secondary succession of native forest vegetation, and the substitution of the primary wet meadow habitats in riparian zone continues today. Accordingly, the natural forest communities Populetum nigro–albae and Fraxino–Quercetum roboris are extensively replaced by new community of invasive species Fraxinus pennsylvanica. On the other hand, Acer negundo has expanded even more and increasingly occupies the habitats of the native community Salicetum albae pannonicum (next to local waters), and some habitats of ass. Populetum nigro–albae, forming the stable stands of new invasive community. Similar situation was observed in the middle course of the Vistula river in Poland (Künstler, 1999). However, the substitution of communities is not so |