季节放牧对典型草原植物群落不同生长季特征的影响

在内蒙古典型草原区建立放牧试验平台,研究秋季、冬季和初春放牧对草地植物返青期土壤温湿环境和植物生长以及生长旺季植物群落地上生物量及其构成的影响。结果表明:在草地返青季,秋季放牧草地表层土壤湿度相对于其他处理显著降低,而温度相对升高;土壤表层湿度与草地枯落物总量、立枯量呈显著正相关;秋季和冬季放牧显著降低草地返青期的地上生物量;秋季放牧显著降低优势植物地上生物量;而初春放牧不影响草地返青期的群落生物量。在生长旺季,初春放牧草地群落及其高大优势植物大针茅和羊草的生物量显著增加,而其下层的糙隐子草和杂类草生物量显著减少。

Effects of Different Grazing Seasons on Plant Communities in the Vegetation Green-up and Peak Growing Seasons of a Typical Steppe

Grazing season is a one of key factors for developing sustainable grassland management regimes. We conducted a grazing experiment in the typical steppe region of Inner Mongolia, to examine the effects of grazing in autumn(SF), winter(SW) and early spring(SS) seasons on soil moisture and temperature and plant growth during the vegetation green-up season, as well as the aboveground biomass and its composition of plant communities in the growing season. The results showed that:(1) In the vegetation green-up season, the surface soil moisture of grazing grassland in autumn was significantly lower than of other treatments, and the temperature was relatively higher, the surface soil moisture was significantly positively related to the total amount of litter or standing litter.(2) Grazing in autumn and winter have significantly reduced the plant community biomass in the vegetation green-up season;grazing in autumn significantly reduced the aboveground biomass of dominant plants(Stipa grandis, Leymus chinensis, Cleistogenes squarrosa);while grazing in early spring had no significant effects on plant community biomass.(3) In the peak growth season, the aboveground biomass of grazing grassland communities and their tall dominant species, Stipa grandis and Leymus chinensis increased significantly in the early spring, while the biomass of Cleistogenes squarrosa and other forbs in the lower layers decreased significantly.