Grasslands dominated by Leymus chinensis in the west part of the north-east China and the eastern Inner Mongolia are the main natural pasture forgrazing and hay production,and,therefore, they are highly economicallyvaluable. However,the degradation of these grassland ecosystem are verysevere, mainly due to overgrazing. In this paper,we will use matheinatical models to show the change ofthe relative dominance of plant populations in the retrogressive successionseries.In lightly and moderately grazed grasslands,Leymus chincnsis is thedominance. Its relative dominance changes with increasing grazing intensity,and this change can be described by an equation, In theentire succession series,the changes of the relative dominance of Carex duri-cscula and Clcistogenes squarrosa can be explained using models of(for C. duricscula)and (for C. squarrosa).Therelative dominance of Suaeda corniculata and Chloris virgata increases as thegrassland degrades. Their relative dominance changes can be elucidated bythe following models, D=0.11e￣(1.3T)(for S.corniculata)and D=0.38e￣(10.94T) (forC. virgata) ,respectively. Our results indicate that the shift of dominantspecies is very conspicuous during the retrogressive succession of grassland communities.
Acta Phytoecologica Sinica
Plant population, Mathematical model, Leymus chinensis,Grassland, Inner Mongolia