Grazing exclusion is a commonly used method to protect and recover herbaceous plants in grasslands, and woody expansion is a common phenomenon in grasslands. However, the effects of grazing exclusion on shrub reproduction remain poorly understood. We investigated the effects of long-term grazing exclusion (0, 8, 30 and 34 years) on reproductive effort of Caragana microphylla in the semi-arid Inner Mongolia Steppe. Our results showed that the 8-year grazing exclusion significantly increased the number of flowers, juvenile pods, mature pods and seed (seed number increased 33.5%) of C. microphylla, however, the 30- to 34-year grazing exclusion significantly decreased seed production (seed number decreased 77.9% and 88.1%) of C. microphylla. The 8-year grazing exclusion had no significant effect on the single flower weight, while the 30- to 34-year grazing exclusion significantly decreased (31.7% and 38.7%) the single flower weight. The grazing exclusion had no significant effect on the seed number per pod. The 8-year grazing exclusion significantly increased sexual allocation (31.6%), and it had no significant effect on sexual allocation efficiency; however, the 30- to 34-year grazing exclusion significantly decreased the sexual allocation (50.4% and 70.4%) and sexual allocation efficiency (55.5% and 60.1%). The 8-year grazing exclusion significantly increased seed weight and seed vigor (seed weight increased 18.7%, seed vigor index increased 28.7%), whereas the 30- to 34-year grazing exclusion decreased these indexes (seed weight decreased 14.2% and 21.0%, seed vigor index decreased 9.1% and 14.7%). These results indicated that the 8-year grazing exclusion increased reproductive effort of C. microphylla, while the 30- to 34-year grazing exclusion sharply decreased the reproductive effort of this shrub species. Our study suggests long-term grazing exclusion limited the expansion of shrubs in grassland by decreasing sexual reproduction and thus inhibiting population growth of shrubs.

中文翻译：

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半干旱草原长期禁牧下小叶锦鸡儿的繁殖力

放牧排斥是草原草本植物保护和恢复的常用方法，而木本扩张是草原普遍存在的现象。然而，放牧排斥对灌木繁殖的影响仍然知之甚少。我们研究了长期禁牧（0、8、30 和 34 年）对半干旱内蒙古草原小叶锦鸡儿繁殖力的影响。我们的结果表明，8年的放牧排斥显着增加了小叶小叶的花、幼荚、成熟荚和种子的数量（种子数增加了33.5%），而30-34年的放牧排斥显着减少了种子C. microphylla 的产量（种子数减少 77.9% 和 88.1%）. 8年禁牧对单花重无显着影响，而30-34年禁牧显着降低（31.7%和38.7%）单花重。放牧排除对每个豆荚的种子数没有显着影响。8年禁牧显着增加了性分配（31.6%），对性分配效率无显着影响；然而，30-34 年的放牧排斥显着降低了性分配（50.4% 和 70.4%）和性分配效率（55.5% 和 60.1%）。8年禁牧显着增加种子重和种子活力（种子重增加18.7%，种子活力指数增加28.7%），而30至34年禁牧使这些指标下降（种子重下降14.2%和21.0%） , 种子活力指数分别下降 9.1% 和 14.7%）。这些结果表明，8 年的放牧排斥增加了C. microphylla，而 30 至 34 年的放牧排斥急剧降低了该灌木物种的繁殖力。我们的研究表明，长期的放牧排斥通过减少有性繁殖从而抑制灌木的种群增长来限制草地灌木的扩张。