Abstract: By using enclosed-top chambers to simulate the future climate change, this paper studied the responses of the morphological structure and competition capability of subalpine dominant plant species (Abies faxoniana, Deyeuxia scabrescen, Carex kansuensis, Fragaria orientali, and Cardamine tangutorum) to elevated atmospheric CO₂ concentration and air temperature. After two years exposure, the crown volume, specific crown volume, specific leaf area, and specific root length of A. faxoniana under elevated atmospheric CO₂ concentration increased by 42%, 65%, 17%, and 19%, respectively. Under elevated air temperature, A. faxoniana grew faster lengthways, its crown volume increased by 22%, and its root/shoot ratio and specific root length increased by 17%. The interaction of elevated atmospheric CO₂ concentration and air temperature increased the crown volume, specific crown volume, specific leaf area, and specific root length of A. faxoniana by 79%, 197%, 17%, and 18%, respectively. Under elevated atmospheric CO₂concentration, the D. scabrescen had an increase of plant height, basal diameter, and leaf number per plant but a decrease of specific leaf area, whereas the C. kansuensis, F. orientali, and C. tangutorum were in adverse. Under elevated air temperature, the root/shoot ratio of D. scabrescen,C. kansuensis, F. orientali, and C. tangutorum decreased, and the plant height and basal diameter of the herbs except C. tangutorum also decreased. The interaction of elevated atmospheric CO₂ concentration and air temperature increased the basal diameter and leaf number per plant of the four herbs, but decreased their specific leaf area and root/shoot ratio. In sum, both elevated atmospheric CO₂ concentration and elevated air temperature promoted the formation of A. faxoniana crown, which was beneficial to the capture of resources and the enhancement of the competition ability per unit mass, but had definite negative effects on the morphological structure and competition ability of the four herbaceous species.

Key words: Sesbania rostrata, Lolium multiflorum, Burying, Pb/Zn tailings, Restoration