Competitive Hierarchy among Three Perennial Grasses under Clipping and Fertilization through Three Growing Years on the Eastern Qinghai-Tibetan Plateau

Abstract

The meadow ecosystem of the Qinghai-Tibetan plateau, the largest rangeland in China, has been degenerating recently from heavy grazing and soil erosion, resulting in decreased carrying capacity and canopy coverage. A field experiment studied the competitive hierarchy among three perennial grasses, Elymus nutans, Festuca sinensis, and Festuca ovina, which distributed widely on the east Qinghai-Tibetan plateau. There were three two-species mixtures at four seeding densities at two fertilization levels and three clipping residual heights measured over three years. Shoot biomass and Relative Competitive Intensity were determined from harvested shoot dry weights. The results showed that E. nutans was a competitive winner in all of the mixtures, regardless of treatments. F. sinensis and F. ovina were inferior competitors compared with E. nutans. The shoot biomass and Relative Competitive Intensity were greatest for E. nutans, then F. sinensis, and least for F. ovina in the 2nd year but in the 3rd year F. ovina surpassed F. sinensis. Fertilization and clipping treatments had significant effect on species’ shoot biomass and no significant effects on Relative Competitive Intensity. The results showed that the mixtures of E. nutans / F. sinensis and E. nutans / F. ovina are appropriate mixture combinations to maintain high shoot biomass and stable community patterns on the Qinghai-Tibetan plateau. They are good choice to improve grassland, and provide benefits for both local economic development and environmental protection.