Effects of grazing management system on plant community structure and functioning in a semiarid steppe: scaling from species to community

Abstract

Under the aim of searching for a more sustainable grazing management system, a mixed management system (grazing and haymaking alternate annually) was proposed and tested against traditional management system (used consistently either for grazing or haymaking) in the semiarid grassland of Inner Mongolia with a field manipulation experiment. The responses of aboveground biomass to the two grazing management systems were examined across different levels of organization (i.e., species, plant functional group, and community) and in five consecutive years from 2005 to 2009. The effects of the two systems on seed production potential of four dominant species (Leymus chinensis, Stipa grandis, Agropyron cristatum, Cleistogenes squarrosa) were also investigated. Our results demonstrate that, in the traditional system, aboveground biomass production across all the levels of organization was reduced by grazing. In mixed system, however, no significantly negative relationship between the biomass response and stocking rate was detected at all organization levels. Precipitation fluctuation had strong influence on biomass responses, and compared to the traditional system the slope of the biomass-precipitation relationship tends to be higher in the mixed system. This effect might be attributed to the more positive response of L. chinensis and A. cristatum to increase in precipitation. In the traditional system, both the ratio and the density of reproductive tillers of the grazing subplots were significantly reduced compared to the haymaking or ungrazed control plots. In the mixed system, there was no significant difference between the haymaking subplots and the ungrazed control plots, regardless of the grazing pressures imposed on the haymaking subplots in the previous growing season. Our findings suggest that the mixed system mitigates the sheep grazing-induced species shift and it tends to be more responsive to increasing precipitation as compared to the traditional system. Therefore, replacement of the traditional grazing strategy with the mixed system could provide an important contribution to sustainable land-use of the Inner Mongolia grasslands.

Effects of mowing regimes and climate variability on hay production of Leymus chinensis (Trin.) Tzvelev grassland in northern China

“…The effects of climate on the herbage production from ungrazed L. chinensis grasslands have been reported in several papers (Jiang 1988;Xiao et al 1996;Bai et al 2004;Wang and Zhou 2004;Wang et al 2005) as well as under livestock grazing (Li et al 2008;Wan et al 2011), but not under mowing except for the early reports from this study (Zhong and Piao 1988;Bao et al 2005a). All of these production studies (Jiang 1988;Xiao et al 1996;Bai et al 2004;Wang et al 2005;Li et al 2008;Wan et al 2011) focussed on herbage production, which was always greater than the harvestable herbage from haymaking.…”

“…All of these production studies (Jiang 1988;Xiao et al 1996;Bai et al 2004;Wang et al 2005;Li et al 2008;Wan et al 2011) focussed on herbage production, which was always greater than the harvestable herbage from haymaking. The average residual height after mowing in the L. chinensis grassland was 6 cm in the region (Zhong 1991).…”

Nitrogen enrichment and grazing accelerate vegetation restoration in degraded grassland patches

“…In grazed plots, plant seeds are carried into degraded patches by livestock from nearby natural grasslands, thus increasing the species similarity and biodiversity. Additionally, the feeding preferences of grazing animals both directly and indirectly alter interspecific plant competition, further influencing both species composition and community structure (Dreber et al, 2011;Noymeir et al, 1989;Wan et al, 2011). It should be noted that grazing intensity is a crucial factor regulating the restoration of degraded grassland patches.…”

“…Many factors may affect the restoration of degraded grasslands, such as grazing intensity (Wiesmeier et al, 2012;Zhao et al, 2004), available soil nutrition (Holst et al, 2009;Zhang et al, 2012), seed dispersal (Bullock et al, 2003;Czarnecka, 2005;Dyer, 2002;Wurm, 1998), and precipitation (Li et al, 2011). Scientists have previously analyzed the restorative effects of various techniques on degraded grasslands, including fencing, controlled grazing (Dormaar and Willms, 1998;Krummelbein et al, 2009;Wan et al, 2011) and nitrogen (N) and water addition (Brueck et al, 2010;Fanselow et al, 2011;Lu and Han, 2010;Ruan et al, 2012). However, few studies have investigated the effects of N enrichment (or increasing atmospheric N deposition) and grazing on the restoration of degraded grassland patches.…”

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

“…Abundant evidence demonstrates that the bite effect of grazing livestock reduces the vegetation coverage and the height of community (Medina-Roldán et al 2012;Zhu et al 2016). The influence of grazing on the plant community lies in two ways, i.e., the direct impact through diet preference and trampling of livestock on plant's survival, growth, and fecundity and the indirect one by altering the intraspecific and interspecific interactions or the water and nutrient availability (Wan et al 2010). The response of the aboveground and belowground biomass allocation to grazing, however, is unclear, because the strategies of allocation in plant under grazing are very controversial (Yang et al 2009;Gao et al 2007;An and Li 2015), which led to observation results of decreased belowground biomass (Deng et al 2014a) and also increased ones (Gao et al 2007) related to grazing.…”