Productivity and botanical diversity in the steppe grassland of Inner Mongolia - contributions of grazing intensity and potential of forage legume species
Final Report Abstract
In this study we intended to analyze the potential of five dominant legumes native to semi-arid agro-pastoral zone of northern China, with or without rhizobia inoculation, for their use in re-vegetation grassland in Inner Mongolia steppe. The nodulation and growth of Medicago falcata, Melilotoldes ruthenica, Caragana mycrophylla, Medicago sativa and Melilotus suaveolens was assessed. We tested seedling performance and nitrogenfixation ability in the soil of ungrazed 79 plots which own more active rhizome bacteria collected from native grassland. To check whether soil rhizobia had a significant effect on plant growth we use (a) soil sterilization and (b) plant inoculation with native rhizobia strains and (c) extra nitrogen fertilizer adding treatment. Due to our overall hypothesis we expected a promising potential for re-establishment of indigenous legumes in Inner Mongolia grassland. However, this approach failed. The reasons for the non successful establishment in the field experiment were i. a poor winter survival of seedlings and ii. a strong pasturing damage by grasshoppers, while the reason for the failed pot experiment is obviously to be seen in non adapted rhizobia strains as no nodulation occurred. Due to these results, not worth publishing, we decided to change the work program and used data sets from P3 from the MAGIM project, which had not been processed, yet, for further investigations. Thus we analyzed how precipitation and temperature are driving botanical composition based on a six year dataset. Using stepwise regressions we could identify a strong interaction between temperature and precipitation in spring on the one hand and C4 species abundance and the relative performance of Leymus chinensis and Stipa grandis on the other hand. Additionally the forage value (IVDOM; CP) of the most significant species was analyzed during the grazing season indicating that C4 species contribute significantly to a higher forage quality in the late season of the grazing period and thus can contribute to a sufficient animal performance during this crucial period although these species are identified as increasers due to overgrazing. Finally the effects of grazing pattern due to different grazing pressure were analyzed in terms of ecosystem functioning. The results reveal a more homogeneous biomass distribution in the ungrazed and heavily-grazed plots compared to lightly-grazed plots, in which selective grazing of sheep rather induces heterogeneous biomass distribution patterns including both overgrazed hotspots and rather rejected areas. The patch patterns under lightly-grazed intensity are consistent during years. With regard to optimized management options for livestock production and ecosystem functioning of steppe ecosystems, the patch grazing in the continuous system is not necessarily indicating negative effects on grassland ecosystem functioning. Patchy structure rather than homogeneous pattern showed higher biodiversity and better potential of rich seed bank; significant variations in litter, soil water content and soil temperature; less effect on belowground biomass and carbon storage.
Publications
- Effects of Grazing Intensity, Precipitation and Temperature on Species Composition and Diversity in Typical Steppe of Inner Mongolia, China. PLoS One, 2012
Haiyan Ren, Philipp Schönbach, Hongwei Wan, Martin Gierus, Friedhelm Taube
(See online at https://doi.org/10.1371/journal.pone.0052180) - Grazing effects on the nutritive value and nutritional yields of forage in Inner Mongolian grassland. Proc. Soc. Nutr. Physiol., 21, 2012
Haiyan Ren., Hongwei W., Schönbach P., Gierus M., Taube F.
- Grazing effects on the quality and quantity of forage In Inner Mongolian grassland. Proceedings of the 24th General Meeting of the European Grassland Federation, Grassland Science in Europe 17: 264-266, 2012
Haiyan Ren., Hongwei W., Schönbach P., Gierus M., Taube F.
- Scale-dependent effects of grazing on plant C: N: P stoichiometry and linkage to ecosystem functioning in the Inner Mongolia grassland. PLoS One. 2012
Shuxia Zheng, Haiyan Ren, Wenhuai Li, and Zhichun Lan
(See online at https://doi.org/10.1371/journal.pone.0051750) - Forage nutritional characteristics and yield dynamics in a grazed semiarid steppe ecosystem of Inner Mongolia, China. Ecological Indicators, Volume 60, January 2016, Pages 460-469
Haiyan Ren, Guodong Han, Philipp Schönbach, Martin Gierus, Friedhelm Taube
(See online at https://doi.org/10.1016/j.ecolind.2015.07.027)
