Grassland responses to grazing: effects of grazing intensity and management system in an Inner Mongolian steppe ecosystem
- 1.9k Downloads
The major aims of this study were, firstly, to analyse the grazing-induced steppe degradation process and, secondly, to identify an efficient and sustainable grazing management system for the widely degraded Inner Mongolian typical steppe ecosystem. From 2005–2008 a grazing experiment was conducted to compare two grazing management systems, the Mixed System (MS) and the Traditional System (TS), along a gradient of seven grazing intensities, i.e. ungrazed (GI0), very-light (GI1), light (GI2), light-moderate (GI3), moderate (GI4), heavy (GI5), and very-heavy (GI6). Each grazing intensity treatment was considered a production unit comprising two adjacent plots, one for hay-making (single-cut system) and one for grazing. Hay-making and grazing alternated annually in the MS, while in the TS the same plots were used either for hay-making or for grazing. Effects of management system, grazing intensity, and year on end-of-season standing biomass (ESSB), aboveground net primary production (ANPP), relative difference in ANPP between 2005 and 2008 (ANPPDiff), relative growth rate (RGR), and sward characteristics (litter accumulation, soil coverage) were analysed. Litter accumulation of production units was affected by grazing intensity (P < 0.001) and decreased from GI0 to GI6 by 83%. Correspondingly, soil coverage decreased (P < 0.001) from GI0 to GI6 by 43%, indicating an increased vulnerability to soil erosion. We found varying compensatory growth responses to grazing intensity among years, probably because of temporal variability in precipitation. The ability of plants to partially compensate for grazing damage was enhanced in years of greater seasonal precipitation. The ANPP of production units was negatively affected by grazing intensity and decreased from GI0 to GI6 by 37, 30, and 55% in 2006 (P < 0.01), 2007 (P < 0.05), and 2008 (P < 0.001), respectively. The effect of management system × grazing intensity interaction on ANPP (P < 0.05) and ANPPDiff (P < 0.05) suggested greater grazing resilience of the MS as compared to the TS at GI3 to GI6.
KeywordsAboveground net primary production Degradation Leymus chinensis Relative growth rate Semiarid grassland Sheep grazing Stipa grandis Typical steppe
Aboveground net primary production
End-of-season standing biomass
Relative growth rate
The authors would like to acknowledge the Deutsche Forschungsgemeinschaft (DFG) for funding the research group 536 MAGIM (Matter fluxes of grasslands in Inner Mongolia as influenced by stocking rate). The authors are also grateful to the IMGERS (Inner Mongolia Grassland Ecosystem Research Station) for the technical support and provision of infrastructure, to Yuandi Zhu for organisation, as well as to the numerous trained local operators as they enabled the enormous data collection by untiring efforts.
- Allen VG, Bagley P, Ballerstadt P, Baxter H, Bransby DI, Brown TF, Buxton D, Child D, Coffey J, Degarmo H, Fribourg HA, Hood M, Horn F, Johnson DA, Kesler E, Khattat F, Kothmann M, Lacefield G, Martz F, Matches AG, McCawley P, Pearson H, Phillippi D, Reid L, Sleper D, Staples C, Undersander D, Vough L, Wallace JD, Williamson R, Willoughby J, Hodgson J, Minson D (1992) Terminology for grazing lands and grazing animals. J Prod Agric 5:191–201Google Scholar
- IUSS Working Group WRB (2006) World reference base for soil resources 2006, 2 edn. World soil resources reports. FAO, RomeGoogle Scholar
- Schönbach P, Wan H, Gierus M, Bai Y and Taube F (2008) Relationship between sward surface height and agronomic traits in the typical steppe of Inner Mongolia. In International Grassland and International Rangelands Congress. p. 1160. Supplementary 2008 XXI International Grassland and VIII International Rangelands Congress Proceedings, Hohote, ChinaGoogle Scholar
- Steel RGD, Torrie JH (1980) Principles and procedures of statistics—a biometrical approach. McGraw-Hill, New YorkGoogle Scholar
- Suttie JM, Reynolds SG, Batello C (2005) Grasslands of the world. FAO, Rome, p 514Google Scholar