Effect of fencing and grazing on a Kobresia-dominated meadow in the Qinghai-Tibetan Plateau

Abstract

Grazing is one of the most important factors influencing community structure and productivity in natural grasslands. Fencing to exclude grazers is one of the main management practices used to protect grasslands. Can fencing improve grassland community status by restraining grazing? We conducted a field community study and indoor soil analyses to determine the long-term effects of fencing and grazing on the above-ground community and soil in a Kobresia-dominated meadow in the Qinghai-Tibetan Plateau, NW China. Our results showed that fencing significantly improved aboveground vegetation productivity but reduced plant density and species diversity. Long-term fencing favored the improvement of forage grass functional groups and restrained the development noxious weed functional groups. There were significant positive effects of fencing on below-ground organic matter, total nitrogen, available nitrogen, total phosphorus and available phosphorus. The productivity of grazed meadow showed a weak decrease over time. There were long-term decreasing trends for plant density both in fenced and grazed meadows. Our study suggests that grazing can be considered as a useful management practice to improve species diversity and plant density in long-term fenced grasslands and that periodic grazing and fencing is beneficial in grassland management.

Soil properties and species composition under different grazing intensity in an alpine meadow on the eastern Tibetan Plateau, China

“…where PPG is the aboveground biomass of Gramineae and Cyperaceae species and TAB is the total biomass of all species in the quadrate (Wu et al 2009). …”

“…At the community level, the plant community composition was observed to be altered with grazing or fencing (grazing exclusion) (Wu et al 2009), which was characterized by the variations of the ratio between palatable grasses and unpalatable grasses. With grazing, the dominant species of the plant community shifted from palatable grasses (Gramineae and Cyperaceae) in UG to unpalatable grasses (Compositae and Ranunculaceae) in grazed meadow (Table 4).…”

“…Through their diet preference, the yaks reduced the proportion of palatable grasses in the species and the biomass in the whole community and therefore made dominant the unpalatable grasses. From the perspective of the grasses, palatable grasses have greater competitive ability than unpalatable grasses in the absence of grazing (Moretto and Distel 1997;Wu et al 2009) and more regenerative potency under the disturbance of grazing (Belsky et al 1992). In addition, the proportion of palatable grasses of the community is the largest in lightly or moderately grazed grassland, but the vigor of palatable grasses is reduced in overgrazed ones.…”

“…However, overgrazing is one of main causes of grassland desertification (Deng et al 2014a;Su et al 2005;Wu et al 2009), including desertification of soil properties (chemical and physical) and negative effects of vegetation, including reduction in biomass, vegetation coverage, and species diversity and increase in undesirable vegetation (Deng et al 2014a;Zhu et al 2016). Grazing prohibition (exclusion) or fencing is the common grassland management to reverse desertification grassland throughout the world in recent decades (Deng et al 2014b;Deng et al 2014a;Ma et al 2015;Wu et al 2009), andFeng et al (2010) founded that Elymus natans establishment is an effective and applicable measure in restoring heavily degraded alpine meadow in the region of the Qinghai-Tibetan Plateau through 3-and 7-year-old E. natans re-vegetated grasslands.…”

“…Currently, 4.67 × 10 6 hm 2 alpine meadow is degraded, accounting for 25% of the total area of this region and approximately half of the total alpine grassland (Dong et al 2013). In terms of vegetation recovery and soil property improvement for the alpine meadow, livestock exclusion or fencing rather than grazing was found to be beneficial, which changes the biomass and soil properties to the better (Shi et al 2010;Ma et al 2015;Wu et al 2009). The lightly and moderately degraded alpine meadow was found to recover by being kept away from disturbance, whereas the heavily and extremely heavily degraded alpine meadow requires artificial and semi-artificial grassland establishment for ecosystem restoration (Dong et al 2013;Feng et al 2010).…”