Classification of alder forests on sandy massifs in the Rostov region

The results of geobotanical survey of Alnus glu­ti­nosa arena forests at three sandy areas within the North of the Rostov and the West of the Volgograd regions of the Russian Federation are given. The territory is situated at the East European Plain where steppes are zonal type of vegetation. This territory is well developed agricultural region with highly transformed lands. Nevertheless, the fragments of natural vegetation support rather high floristic and phytocoenotic diversity and they contain a number of endemic species also (Fedyaeva, 2002).

Small patches of alder forest stands generally occur in roundish and tape-like depressions on the second and third sandy terraces of the Don River. These woods were in a focus of interest of many scientists, e.g. G. M. Zozulin (1992) who studied these more than 30 years. But the special papers including the ecologo-floristic characteristic of natural arena alder forests were missing up to now.

According to vegetation classification based on the Braun-Blanquet approach (Braun-Blanquet, 1964) the alder forests are referred to four formerly described associations of the alliances Alnion incanae and Alnion glutinosae: Aceri tatarici–Alnetum glutinosae, Urtico dioicae–Alnetum glutinosae, Ficario–Ulmetum minoris and Carici elongatae–Alnetum glutinosae. Proposed 4 subassociations and 10 variants reveal the syntaxonomical structure of these associations.

The comparative analysis of syntaxa of the forests of the alliances Alnion incanae and Alnion glutinosae within the Rostov region, in the Russian Southern Nechernozemje, in Ukraine and the Central Europe was done. It is emphasized that the differentiation of the alder communities is complicated due to their intrazonal positions in a landscape. There are a very few character species at the association level. At the same time a lot of plant communities reflect the ecotone features between the meso-hygrophyte forests of the class Querco-Fagetea and the mire woods of the class Alnetea glutinosae. Therefore we had to apply both the classical and nonclassical syntaxonomical analysis (Mirkin et al., 2009). It is obvious that the alder forests syntaxonomy at the lowest level will be specified in the nearest future. There are noticeable differences in species composition of studied communities depen­ding on their position in landscape. For example, there are communities with a large amount of species of the class Querco-Fagetea occurring in the forest margins and on slopes. The role of species of the class Alnetea glutinosae increases on the gradient from the outskirts of wood massifs to their central parts in lowlands also. Species of the alliance Alnion incanae are widely presented in all communities.

Although the described communities are small in size and rather rare on the territory studied they contain 27 vascular plant species included in the Red Data Book of the Rostov region (Krasnaya…, 2004). These woods considerably increase the biodiversity within the steppe zone as well. The organization of a number of nature reserves is necessary to protect the certain types of alder forests.