Screening of weeds for vegetation recovery in a pasture in the semi-arid region of the loess plateau in China.
In pastures in the semi-arid region of the loess plateau in China, bare ground has expanded due to over-grazing. Field studies were therefore carried out to analyse the vegetation and to identify weed species for vegetation recovery in such degraded pastures. The number of plant species present in pastures differed according to the direction of slope and grazing conditions; 9 species (belonging to 6 families), 14 species (8 families), 18 species (10 families) and 24 species (11 families) were found to be grazed on the southern slope, northern slope, protected southern slope and protected northern slope, resp. Of the 231 weed species introduced from foreign countries, the following 28 grew well on the southern slope, where the conditions were most unfavourable: Carduus nutans, Centaurea cyanus, C. nigra, Tragopogon pratensis, Echium vulgare, Astragalus adsurgens, Lotus corniculatus, Medicago sativa [lucerne], Melilotus alba, M. officinalis, Onobrychis visiaefolia [O. viciifolia], Agropyron cristatum, A. elongatum [Elymus elongatus], A. intermedium [Elymus hispidus], A. mongolicum, A. repens [Elymus repens], Avena fatua, Avena ludoviciana [A. sterilis subsp. ludoviciana], Bromus inermis, Elymus angustus [Leymus angustus], Elymus dahuricus, Elymus junceus [Psathyrostachys juncea], Elymus sibiricus, Festuca ovina, F. pratensis, Oryzopsis hymenoides, Setaria faberi and S. viridis.