AACL Bioflux, 2013, Volume 6, Issue 2. http://www.bioflux.com.ro/aacl 115 AACL BIOFLUX Aquaculture, Aquarium, Conservation & Legislation International Journal of the Bioflux Society Presence of alien ligneous species in some plant associations from Danube Delta and their management 1 Bogdan M. Negrea, 2 Mihai Doroftei, 3 Meike Grimm, and 1 Cătălin C. Roibu 1 Faculty of Forestry, University "Ştefan cel Mare" Suceava, Suceava, Romania; 2 Danube Delta National Institute for Research and Development, Tulcea, Romania; 3 University of Leipzig, Faculty of Physics and Geosciences, Department of Geography, Leipzig, Germany. Corresponding author: B. M. Negrea, bogdannm@yahoo.com Abstract. This paper presents a brief overview of the most important species of alien woody plants of the Danube Delta. Also presents the habitats where they are found. Stational conditions are studied and described of each habitat type apart, in order to study the affinity of species to certain environmental conditions. In the annex paper there is presented each habitat where woody alien plants appear. Also there is an overview and rehabilitation measures that are required of these habitats. Key Words: vegetal associations, ligneous species, alien species, habitat restoration, basin area. Rezumat. Lucrarea prezintă o trecere în revistă a celor mai importante specii de plante lemnoase alohtone din Delta Dunării, cât şi a habitatelor unde acestea se întâlnesc. De asemenea, sunt descrise condiţiile staţionale ale fiecărui tip de habitat în parte pentru a putea studia afinitatea unor specii pentru anumite condiţii de mediu. În anexa lucrării sunt prezentate habitatele unde plantele alohtone lemnoase apar. De asemenea sunt trecute în revistă şi măsurile ce se impugn pentru reabilitarea habitatelor afectate de aceste plante alohtone. Cuvinte cheie: asociaţii vegetale, plante lemnoase, specii alohtone, reabilitarea habitatelor, zona depresionară. Introduction. Growing number of naturalized alien species is perceived as an important indicator of global uniformization. It is shown the fact that the changes in distribution of a species are natural phenomena. The natural area of an species can extend or reduce. Such species can colonize new regions outside the natural area. Nevertheless, such events are rare and often restricted by natural barriers (Wittenberg 2005). Globalization as an actual fenomena can lead to uniformity, without having the natural barriers as an important factor in maintaining biological diversity (Blossey & Notzold 1995; Anastasiu & Negrean 2005). Current perception over the invasion process in a distorted one. This fact is due to actions of monitoring and control are focused only on aggressive species, which eliminates the native ones or change the invaded ecosystem (Cogălniceanu 2007). The main purpose of this paper is to establish the trends of vegetation evolution in some areas of Danube Delta. Pressure of alien species and all nowadays global changes also have an important role in our study. Material and Method. The relevee and transect method was employed in the field (according to coverage – percentage method). The species have been recorded on an established surface (100 m 2 ) meant to reflect the average characteristics of the investigated areas.