TORE C., TOKUR S. & KETENOGLU O. 2005. Contributions to the syntaxonomy and ecology of the forest and shrub vegetation in Bithynia, Northwestern Anatolia, Turkey - Phyton (Horn, Austria) 45(l): 81-115, 4 figures. - English with German summary. The forest vegetation of the investigated area has been studied using the BRAUN-BLAUNQUET approach. The following associations were described: Two shrub associations, the Junipero oxycedri-Quercetum pubescentis ass. nova and the Hieracio pannosi-Cistetum laurifolii ass. nova were included in the alliances Quercion anatolicae and Pino-Cistion laurifolii respectively. They are together with Carpino-Acerion united in the order Querco-Carpinetalia orientalis, which comprises the mesophilous forest and shrub vegetation types of NW Anatolia. The forest associations Argyrolobio biebersteinii-Quercetum cerridis ass. nova, Stellario holosteae-Pinetum pallasianae ass. nova, Daphno ponticae-Pinetum sylvestris, and Fago orientalis-Abietetum bornmuelleriana were attached to the alliance Carp ino-Acerion, the Junipero, foetidissimae-Juniperetum excelsae ass. nova to the alliance Quercion anatolicae of the class Quercetea pubescentis. Only the Trachysterno orientalis-Fagetum orientalis belongs to the order Rhododendro-Fagetalia orientalis of the class Querco- Fagetea. The manually sorted releves have been classified on the basis of their floristical and ecological peculiarities. All forest stands in the area develop under a semi-dry and less rainy type of Mediterranean climate and on soils derived from limestone and schistous parent rock.