Abstract:

The correlation between the desertification of the grassland and the change of vegetation biomass in Erduosi was reported in this paper. The results showed that, in the desertification course of the grassland, the degradation pathway of the community was both from S. bungeana community→S.bungeana+died Artemisia ordosia community→S.bungeana+A.ordosica community→Stipa bungeana community→sandland and from A.ordosica community→A.ordosica+Cynanchum komarovii commmunity→C.komarovii commmunity→sandland. From S. bungeana community to A.ordosica community and then to C.komarovii commmunity, the biomass of vegetation increased firstly and then decreased, namely from 218.1g/m² to 748.7gm² and to 155.6 g/m². The biomass of every community varied seasonally, because of the changes of dominant species and companion species. Most of the biomass aboveground distributed near the surface layer, 76.9%～86.3% of the biomass in 0～20 cm. Meanwhile, the biomass decreased gradually with the increasing of height, 10.8%～16.7% of the biomass in the 20～30 cm layer, 2.2%～7.5% in 30～40cm layer, 0.6%～2.9% above 40cm. The underground, 85.5%～100% of the biomass in 0～20cm, 9.7%～12.0% in 20～40cm, 0～2.5% in under 40cm. In the course of biomass accumulation, S. bungeana community and S.bungeana+died A.ordosia community decreased firstly and then increased, the accumulation ratio is from -0.29 to 0.42 and from -0.47 to 0.74, respectively. S.bungeana+A.ordosica community and S. bungeana community decreased steadily, the accumulation ratio is from -0.04 to -0.40 and -0.23, respectively. But A.ordosica+C.komarovii commmunity and C.komarovii commmunity increased steadily, the accumulation ratio is, respectively, from 0.14 to 0.29 and from 0.52 to 0.04.

Key words: Desertification, Biomass, Vertical distribution, Accumulation ratio