Grassland responses to grazing: effects of grazing intensity and management system in an Inner Mongolian steppe ecosystem
Grassland responses to grazing: effects of grazing intensity and management system in an Inner Mongolian steppe ecosystem
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DOI：
10.1007/s11104-010-0366-6
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发表时间：
2011-03-01
期刊：
影响因子：
4.9
通讯作者：
Taube, Friedhelm
中科院分区：
文献类型：
--
作者：
Schoenbach, Philipp;Wan, Hongwei;Taube, Friedhelm
本研究的主要目的是，首先，分析放牧引起的草原退化过程，其次，确定一个有效的和可持续的放牧管理系统，广泛退化的内蒙古典型草原生态系统。从2005 - 2008年，采用混牧（MS）和传统放牧（TS）两种放牧管理方式，沿着7个放牧强度梯度（未放牧（GI 0）、极轻度放牧（GI 1）、轻度放牧（GI 2）、轻中度放牧（GI 3）、中度放牧（GI 4）、重度放牧（GI 5）和极重度放牧（GI 6））进行放牧试验。每个放牧强度处理被认为是一个生产单元，包括两个相邻的地块，一个干草制造（单割系统）和放牧。干草制造和放牧每年交替在MS中，而在TS相同的地块用于干草制造或放牧。分析了不同管理制度、放牧强度和年份对草地生物量、地上净初级生产量、2005年和2008年草地净初级生产量的相对差异、相对生长率和草地特征（凋落物积累量、土壤覆盖度）的影响。生产单位凋落物积累量受放牧强度的影响（P < 0.001），从GI 0到GI 6减少了83%。相应地，从GI 0到GI 6，土壤覆盖度下降了43%（P < 0.001），表明土壤侵蚀的脆弱性增加。我们发现不同的补偿生长反应放牧强度之间的年份，可能是因为降水的时间变化。植物的能力，以部分补偿放牧损害的增强，在年更大的季节性降水。放牧强度对各生产单元的净初级生产力有显著的负影响，从GI 0到GI 6，2006年、2007年和2008年的净初级生产力分别下降了37%（P <0.01）、30%（P < 0.05）和55%（P < 0.001）。管理制度与放牧强度互作对草地净初级生产力和净初级生产力差异的影响显著（P <0.05），表明草地的放牧恢复力高于草地。
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 20052008 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 x grazing intensity interaction on ANPP (P < 0.05) and ANPP(Diff) (P < 0.05) suggested greater grazing resilience of the MS as compared to the TS at GI3 to GI6.