Effect of Grazing Exclusion on Vegetation Characteristics and Soil Organic Carbon of Leymus chinensis Grassland in Northern China

Abstract

Abstract:Overgrazing has caused vegetation destruction and soil degradation in Leymus chinensis grassland, the widely distributed type of grassland in northern China. To restore the degraded ecosystem, grazing exclusion was implemented in 1979, 1999, and 2004. However, changes in the vegetation and soil organic carbon (SOC) in different years of grazing exclusion have not been thoroughly elucidated. This paper examines the changes in vegetation characteristics (i.e., biomass, cover, richness, degree of succession, and shannon diversity index) and SOC under free of grazing (FG), 6 years (6 GE), 11 years (11 GE), and 31 years (31 GE) of grazing exclusion plots in the Xilin River Basin, China. The results indicate that the vegetation characteristics and SOC increased during the restoration process. Both the vegetation characteristics and SOC in 6 GE did not differ significantly from FG (p > 0.05), while these indexes in 11 GE were significantly higher than in FG. The differences between the vegetation characteristics and SOC in 11 GE and those in 31 GE were not significant. To meet the tradeoff between ecosystem conservation and utilization, further studies with multi-year observation should be conducted to identify the optimal duration of grazing exclusion and the grazing exclusion time threshold in L. chinensis grassland. This study provides valuable insights into sustainable grassland management in northern China.

Grazing exclusion—An effective approach for naturally restoring degraded grasslands in Northern China

“…A meta‐analysis by other researchers revealed that grazing exclusion increased the amount of carbon by 112% as litter fall, belowground biomass by 26%, and soil carbon by 14% compared with other grazing practices (Xiong et al, ). Similarly, a study in the Xilin River basin of northern China with Leymus chinensis L. and Carex tristachya showed that as the exclusion duration increased from 0 to 11 years, SOC stocks increased by 14.3% (or 0.26 g kg −1 of soil; Chen & Tang, ). However, a further increase of grazing exclusion duration from 11 to 31 years did not increase SOC stocks.…”

“…To curb further degradation and rejuvenate degraded grasslands, China implemented a series of policies. ‘Grazing exclusion’ was established in 1979 (Chen & Tang, ) with the goal of total elimination of grazing. A follow‐up programme ‘Grain‐for‐Green’ was established in the late 1990s to encourage food production without affecting grassland ecosystems.…”

Does Grazing Exclusion Improve Soil Carbon and Nitrogen Stocks in Alpine Grasslands on the Qinghai-Tibetan Plateau? A Meta-Analysis

“…In the compiled studies, the duration of grazing exclusion varied from 1 year to 11 years. Compared to short-term grazing exclusion, grazing exclusion with longer years often leads to higher plant productivity and coverage because the exclusion of livestock grazing creates a suitable environment for plant growth [58]. In this case, the inputs of soil organic matter (e.g., litter and dead roots) may increase with the duration of grazing exclusion and contribute to continuous accumulations in both SOC and STN stocks.…”

Effects of Major Grassland Conservation Programs Implemented in Inner Mongolia since 2000 on Vegetation Restoration and Natural and Anthropogenic Disturbances to Their Success

“…While many scholars suggest that the grassland conservation programs have had positive impacts on restoring grassland vegetation [23][24][25][26], others argue that these programs have generated negative impacts on the larger scale ecosystem. Critics of the programs point out that grazing pressures were shifted to non-program areas, thus increasing grassland degradation in non-program areas, and that illegal grazing activities were common [27][28][29].…”