石羊河上游甘肃臭草型退化草地植被恢复过程

Rehabilitation Process of Degraded Melica Przewalskyi Grassland in the Upper Reaches of Shiyang River

研究了化学除莠+适度放牧条件下,祁连山北坡甘肃臭草(Melica przewalskyi)草地群落的植被恢复过程。结果表明,使用专用除草剂杀灭甘肃臭草后,恢复草地在2000～2006年经历了甘肃臭草优势阶段、冷蒿+甘肃臭草阶段、冷蒿+阿尔泰针茅阶段、阿尔泰针茅+杂类草阶段等4个演替阶段。2006年草地群落的植物种数比对照草地增加4～7种,盖度和密度接近或高于对照草地,甘肃臭草由优势种变为伴生种,阿尔泰针茅(Stipa. krylovii)成为优势种。与对照草地相比地下总根量减少9.06%,活根量提高3.5%,并且表现出深层化分布趋势,0～50cm土层的含水量提高7.2%。经过7a的恢复演替,草地群落的稳定性增加,但是,草地的地上生物量仍然较低,杂类草所占比例较大,尚未达到成熟群落状态。

The processes of vegetation rehabilitation were studied through applying special herbicide to control Melica przewalskyi Roshev and reducing grazing pressure in Qilian mountain. The results showed that after the management with special herbicide the grassland came through four succession phases for rehabilitating from 2000 to 2006, predominant stage of Melica przewalskyi, Artemisia frigid and Melica przewalskyi stage, Artemisia frigida and Altai Stipa stage, Altay Stipa and forbs stage. Compared with control, the vegetation species in treated grassland increased 4 to 7 species in 2006, and no significant difference for cover and density. In this rehabilitating process, Melica przewalskyi from dominant species changed into companion species, and Stipa. Krylovii became dominant species. Meanwhile, the total root biomass decreased 9.06% and living root biomass increased 3.5% compared with control. The changing of root biomass showed a deeply underground distribution trend. And average soil water content in 0 -50 cm depth increased 7. 21% compared with control in the same layer. After seven-year restoration, the vegetation coverage of the grassland reached 80%, and the stability of grassland community increased. However the above-ground biomass is still very low, and the forbs still take a large proportion, which showed that the grassland community is still in immature state.