Contribution a l'etude ecologique et phytosociologique des adventices des cultures et des jacheres dans le secteur phytogeographique de l'Algerois (Algerie)
The weed vegetation in arable land, under permanent crops and on short term fallow land was studied in Northern Algeria in the surroundings of Algier and adjacent regions by a phytosociological approach in order to describe the plant commmunities and to characterize their ecology. Most sampling sites have been on calcareous substrate and on black cotton soils. The study area is differentiated by a gradient from a humid to a semi-arid mediterranean climate. The spontaneous vegetation on fallow land in the sub-humid bioclimate and on heavy soils can be classified into the Ammio visnagae-Capnophylletum peregrini, the Senecio delphinifoliae-Fedietum cornucopiae ass. nov., and the Tetragonologo purpureae-Cerinthetum majoris. All these communities belong to the new alliance Convolvulion tricoloris (Chrysanthemetalia segetum). The weed vegetation in winter cereals (Secalion) is differentiated according to the climatic conditions: The Bunio incrassatae-Galietum tricornis colonizes arable land under subhumid, the Calendulo algeriensis-Psychinetum stylosae under semi-arid conditions. In the latter association occur transgressives from steppic vegetation (Thero-Brachypodietalia, Lygeo-Stipetea). Perennial cultures like vineyards and other root crops are characterized by the Ormeni-Silenetum fuscatae (Oxalido cernuae-Fumarion capreolatae, Chenopodietalia, Stellarietea mediae).