补播时间和补播草种对退化草甸草原植物群落的影响

气候变化和不合理的利用导致草原退化，探究补播时间及补播草种对植物群落的影响，可为提高草地产量和品质提供理论依据。本试验设置3个补播时间(夏播、秋播、春播)和5种补播材料(扁蓿豆(Medicago varia)、黄花苜蓿(Medicago falcata L.)、杂花苜蓿(Melissilus ruthenicus L.)、‘中科1号’羊草(Leymus chinensis ‘Zhongke No.1’)、野生羊草(Leymus Chinensis (Trin.) Tzvel)，对生物量、多样性指数及温度和降水量进行3年连续监测。结果表明：生长季积温和降水量是影响植物群落的关键因素，降水量与禾本科比例呈显著正相关关系，与其他科比例呈显著负相关关系；随年份增加地上生物量显著增加，而物种丰富度显著降低(P<0.05)；春播羊草提高10%~15%禾本科比例，降低5%~10%其他科比例。综合群落生物量和多样性，在呼伦贝尔干旱年份适宜春季补播羊草，有助于提高禾本科优势牧草比例，提高草地品质，对草地生产力无显著影响。

Effects of Reseeding Time and Species on Plant Community of Meadow Steppe in Hulunbeir

Climate change and unreasonable utilization have led to serious grassland degradation. Climate change and unreasonable utilization lead to grassland degradation. The effects of reseeding time and species on plant communities were explored to provide a theoretical basis for improving grassland yield and quality. The experiment selected three reseeding times (summer,autumn,spring) and five reseeding species (Medicago varia,Medicago falcata L.,Melissilus ruthenicus L.,Leymus chinensis ‘Zhongke No.1’,wild Leymus chinensis),and the aboveground biomass, diversity indices, temperature and precipitation were monitored for three years. The results showed that growing season cumulative temperature and precipitation were key factors influencing grassland plant community,precipitation variation was significantly positively correlated with the proportion of Gramineae and negatively correlated with the proportion of others. Aboveground biomass increased significantly with increasing years,while species richness decreased significantly (P<0.05). Spring reseeding of Leymus chinensis significantly increased the proportion of Gramineae by 10%~15% and decreased the proportion of others by 5%~10%. Combining community biomass and diversity,the suitable spring reseeding of Leymus chinensis in Hulunbuir in dry years can help increase the proportion of Gramineae and improve the quality of grassland,with no significant effect on grassland productivity.