The effects of weed competition, clipping and fertilization treatments on the productivity of cultivated meadows on the Qinghai-Tibetan Plateau

Abstract

. 2010. The effects of weed competition, clipping and fertilization treatments on the productivity of cultivated meadows on the Qinghai-Tibetan Plateau. Can. J. Plant Sci. 90: 173Á177. 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 was designed to test the effects of four treatments (density, fertilization, clipping, and species). The results show that a mixture of forage species provides the greatest increase meadow productivity and community stability. There was a 28% increase in target species yield in a two species mixture compared with a monoculture and a 103% increase in a three species mixture. Fertilization resulted in a 63% increase in the target species yield and a 54% increase in weed yield, but decreased weed abundance. Clipping had an adverse effect on meadow productivity and weed growth (abundance and yield), decreasing the target species yield by 46% relative to no clipping, and decreasing the weed yield by 6%. Elymus nutans was a competitive winner in all of the mixtures, regardless of treatment. A three-way ANOVA showed that the three speciesmixture was the optimal combination for the development of a cultivated meadow. Clipping had no significant effect on the meadow yield but significantly decreased weed abundance. This three-species mixture not only increased yield, but also resistance to weed growth, thus making the mixture a good choice to improve rangeland, and provide benefits for both local economic development and environmental protection.Key words: Clipping, fertilization, mixture, rangeland, weed Gu, M. H., Wen, S. J., Zhang, S. T. et Du, G. Z. 2010. Incidences de la concurrence des mauvaises herbes, de la tonte et de la fertilisation sur la productivite´des prairies cultive´es du plateau du Qinghai-Tibet. Can. J. Plant Sci. 90: 173Á177. L'e´cosyste`me prairial du plateau du Qinghai-Tibet, la plus vaste re´gion de grands parcours de Chine, s'est re´cemment de´grade´en raison d'une paissance excessive et de l'e´rosion du sol qui en ont diminue´la capacite´de charge et la couverture ve´ge´tale. Les auteurs ont conc¸u une expe´rience sur le terrain pour ve´rifier les effets de quatre traitements (densite´, fertilisation, tonte et diversification des espe`ces). Les re´sultats indiquent que le me´lange d'espe`ces fourrage`res assure la plus forte hausse du rendement des prairies et la meilleure stabilite´du peuplement. Avec le me´lange a`deux espe`ces, le rendement de l'espe`ce vise´e s'est accru de 28 % comparativement au rendement de la monoculture; le me´lange de trois espe`ces a quant a`lui entraıˆne´une hausse de rendement de 103 %. La fertilisation accroıˆt le rendement de l'espe`ce vise´e de 63 % et celui des mauvaises herbes de 54 %, l'abondance de ces dernie`res se trouvant ne´anmoins re´duite. La tonte a l'effet contraire sur la productivite´des prairies et la croissance des mauvaises herbes (abo...