Performance of cultivated perennial grass mixtures under different grazing intensities in the alpine region of the Qinghai‐Tibetan Plateau

Abstract

In 1998, seeds of four cultivated native perennial grasses, Bromus inermis (B), Clinelymus nutans (C), Elymus nutans (E) and Agropyron cristatum (A), were sown as mixtures with different seed rates in three combinations (B + C, B + E + A and B + E + C + A) in a field study in the north-eastern part of the QinghaiTibetan Plateau, China. A grazing experiment was conducted in 2000 to investigate the performance of these grass mixtures at leaf, plant and sward scales under different grazing intensities (GI). Four GIs, expressed as the proportion of herbage consumed by Tibetan lambs in relation to the available biomass (IP), were applied in the summer: no grazing, and 0AE30, 0AE50 and 0AE70 of IP. Tiller numbers of the grasses increased and leaf photosynthetic rate, sward leaf area index (LAI) and herbage mass declined with increase in GI. No effect of GI on specific leaf area was observed. Interactions between GI and grass mixtures on the dynamics of species composition, swards' LAI and herbage mass were found. Large fluctuations in species composition with different GIs showed the poor species compatibility and sward persistence of these grass mixtures under high GI by sheep.

Impact and management of crested wheatgrass (Agropyron cristatum) in the northern Great Plains

“…The experiment by Dong et al (2004) also suggests that crested wheatgrass did not compete well against the other native grasses even in sites that were not grazed. One of the Can.…”

“…In its native Asian range, however, crested wheatgrass is apparently less resistant to grazing and competition from native species. Dong et al (2004) conducted a study in the alpine region of the Qinghai-Tibetan Plateau on the ability of crested wheatgrass, and other perennial grasses native to that area, to withstand grazing. In that study, the sites were sown with three different mixtures of seed with different ratios of seed in each.…”

Características estruturais e morfológicas de genótipos de Pennisetum sp. sob pastejo no período de seca

“…Apesar de o pastejo estimular o perfilhamento (Olson & Richards, 1988;Reece et al, 1999;Dong et al, 2004), as condições ambientais no período da seca não são favorá-veis ao desenvolvimento de novos perfilhos (Laude et al, 1968), visto que a deficiência hídrica afeta a taxa de aparecimento de perfilhos (Morales et al, 1997).…”

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

“…Cultivated meadows of mixed perennial grasses have recently been developed in the Qinghai-Tibetan Plateau, with the goal of reducing the degradation caused by heavy grazing pressure (Dong 2004;Xue et al 2005;Gu et al 2009). However, only a limited number of studies have been conducted on the general effects of grazing, fertility and species mixture on the productivity, community stability, and capacity to resist disturbance of the rangeland in the Qinghai-Tibetan plateau, and these factors are poorly understood (Dong et al 2005a,b;Gu et al 2009).…”

“…In most regions, livestock production is still the most important source of income for the local inhabitants. However, in the past several decades, this rangeland has deteriorated and degenerated from overexploitation and natural hazards, such as soil erosion and rodent damage, resulting in decreased rangeland canopy coverage and productivity (Dong et al 2004). …”