Effects of Different Grazing Intensities on Grassland Production in China: A Meta-Analysis

Abstract

BackgroundGrazing is one of the main grassland disturbances in China, and it is essential to quantitatively evaluate the effects of different grazing intensities on grassland production for grassland carbon budget and sustainable use.MethodsA meta-analysis was conducted to reveal general response patterns of grassland production to grazing in China. We used weighted log response ratio to assess the effect size, and 95% confidence intervals to give a sense of the precision of the estimate. Grazing effects were estimated as a percentage change relative to control (%).ResultsA total of 48 studies, including 251 data sets, were included in the meta-analysis. Grazing significantly decreased total biomass by 58.34% (95% CI: −72.04%∼−37.94%, CI: Confidence Interval), increased root/shoot ratio by 30.58% and decreased litter by 51.41% (95% CI: −63.31%∼−35.64%). Aboveground biomass and belowground biomass decreased significantly by 42.77% (95% CI: −48.88%∼−35.93%) and 23.13% (95% CI: −39.61%∼−2.17%), respectively. However, biomass responses were dependent on grazing intensity and environmental conditions. Percentage changes in aboveground biomass to grazing showed a quadratic relationship with precipitation in light grazing intensity treatment and a linear relationship in moderate and heavy grazing intensity treatment, but did not change with temperature. Grazing effects on belowground biomass did not change with precipitation or temperature. Compared to the global average value, grazing had greater negative effects on grassland production in China.ConclusionsGrazing has negative effects on grassland biomass and the grazing effects change with environmental conditions and grazing intensity, therefore flexible rangeland management tactics that suit local circumstances are necessary to take into consideration for balancing the demand of grassland utilization and conservation.

Influence of Grazing Intensity on Swamp Plant Communities in the Tropical Montane Wetland Ecosystems, Nilgiris, Southern India

“…Grazing is a disturbance which can threaten the ability of plant communities to maintain plant species richness and abundance and lead to an altered species composition (Olff and Ritchie, 1998;Walker et al, 2013;Yan et al, 2013;Török et al, 2016). Grazing alters plant diversity through mechanisms that influence local plant colonization ability and extinction dynamics (Olff and Ritchie, 1998;Alofs et al, 2014).…”

“…Grazing by livestock is the main anthropogenic disturbance of native grasslands (Yan et al, 2013) and it plays an important role in determining species composition and plant species diversity (Milchunas et al, 1988(Milchunas et al, , 1989. For instance, grazing intensity is well known to cause changes in the species composition of plant communities (Ren et al, 2012).…”

Ecological Effects of Grazing in the Northern Tianshan Mountains

“…However, grassland ecosystems are easily susceptible to disturbances and highly vulnerable to climate change and human activities, particularly in arid areas [4][5][6][7]. Due to a lack of water resources and complex human activities, ecological processes in arid grasslands may be different from those in humid areas [8].…”

Analysis of Carbon Storage and Its Contributing Factors—A Case Study in the Loess Plateau (China)

“…Second, the measurement accuracy of the NDVI data might have affected the uncertainties of the biomass estimates. Third, differences might be caused by natural selection expressed through plant morphology [27][28][29][30].…”