Effects of grazing exclusion in Xilin Gol grassland differ between regions

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• 作者：Jinghui Liu^a ; Jianjun Wu^b ; ^c ; ^{jjwu@bnu.edu.cn} ; Hongbo Su^a ; Zhihai Gao^d ; Zhitao Wu^e
• 关键词：Grazing exclusion ; Semi-arid grasslands ; Soil organic carbon ; Rehabilitation ; Regional differences
• 刊名：Ecological Engineering
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：99
• 期：Complete
• 页码：271-281
• 全文大小：1936 K
• 卷排序：99

文摘

Establishment of grazing exclusion has become an important rangeland rehabilitation strategy in semi-arid regions. However, the effect of grazing exclusion on soil has been controversial, and the regional differences in these effects have not been investigated sufficiently. Based on field investigation and lab experiments, the present study compared the vegetation cover, vegetation height, biomass, soil organic carbon (SOC), total nitrogen (TN) and available nitrogen (AN) contents inside and outside 18 grazing exclosures that had been established for approximately 10 years in the Xilin Gol grassland. Then, we examined the effect of grazing exclusion on vegetation and soil. We also analyzed the regional differences and the impact factors related to the restoration effects since the Beijing-Tianjin Sandstorm Source Control Project was implemented. Data processing and statistical analyses were carried out with SPSS 13.0. The results showed that the exclosures exhibited significantly (p < 0.01) higher values regarding biomass (153.407 g/m2), vegetation height (27.417 cm) and vegetation cover (62.5%), compared to free grazing lands, where these values were 76.094 g/m2, 12.587 cm and 45%, respectively. This suggested that exclosures are effective in restoring vegetation. The higher the annual precipitation, the better the effect of grazing exclusion on vegetation will be. The exclosures significantly improved soil physical properties: soil bulk density inside the exclosures (1.382 g/cm3) was lower than outside (1.457 g/cm3) in the 0–5 cm depth, and the proportion of soil clay was higher inside the exclosures (0.504%) than outside (0.411%) in the 0–10 cm layer. There were linear declines in the restoration effects for SOC and TN at the 0–10 cm depth with annual precipitation, and areas with more precipitation exhibited no significant or even a negative restoration effects. Therefore, the recovery of soil and vegetation showed regional differences. In follow-up management policies, different climate zones should adopt corresponding grassland management practices.