刈割对天山北坡草甸草原生物量的影响

Effect of Cutting on Meadow Grassland Biomass in North Slope of Tianshan Mountain

[目的]以天山北坡羊茅+杂类草草甸草原为研究对象,研究刈割对草地生物量的影响,探讨地下生物量的形成规律。[方法]采用模拟放牧方式设置休牧、轻度放牧、中度放牧、重度放牧4个处理,测定分析草地生态系统生物量的变化。[结果]随着放牧强度的增大,草本生物量和凋落物逐渐下降,且下降幅度逐渐增大。与休牧相比,轻牧、中牧和重牧的草本生物量分别下降了27.51%,45.28%,65.05%。9月各处理地下生物量与6月相比分别增加了16.05%,13.07%,19.15%,19.08%,0—20cm土层的地下生物量占总地下生物量的85%,呈T型分布,向下递减趋势明显。[结论]放牧强度对植物地上生物量影响明显,表现为:休牧>轻牧>中牧>重牧;季节变化中7月份地上生物量最大,显著高于9月;0—100cm土壤深度中各处理对地下生物量影响表现为:轻牧>休牧>中牧>重牧;各处理下地下生物量的垂直分布变化趋势相同,即地下生物量集中分布在0—10cm土层,该层生物量占总地下生物量的70%,且随着土壤深度增加不断减少;季节变化中,地下生物量变化表现为:9月>6月,各层生物量随土层深度的增加向下递减趋势明显。

[Objective]We took the fescue and miscellaneous grass meadow steppe in the north slope of Tianshan mountain as the research object in order to study the effect of cutting intensity on aboveground and underground biomass of grassland.[Methods]Four treatments including no grazing,light grazing,moderate grazing and heavy grazing were set to investigate the biomass of grassland ecosystem.[Results]With the increase of grazing intensity,herbaceous biomass and litter decreased,and this decrease trend increased gradually.Compared to the no grazing treatment,biomass in light grazing,moderate grazing and heavy grazing were decreased by 27.51%,45.28%,65.05%,respectively.The underground biomass of no grazing,light grazing,moderate grazing and heavy grazing in September increased by 16.05%,13.07%,19.15%,19.08%,respectively,from June.Biomass in 0—20cm soil layer accounted for 85% of the total underground biomass,and the decreasing trend of underground biomass with the increasing soil depths was obvious.[Conclusion]The effect of grazing intensity on aboveground biomass was：light grazing〉no grazing〉moderate grazing〉heavy grazing.The maximum aboveground biomass occurred in July,which was significantly higher than that in September.The effect of grazing intensity on the underground biomass in 0—100cm soil depth was light grazing〉no grazing〉moderate grazing〉heavy grazing.The vertical distribution trend of underground biomass was the same in all different grazing intensities.Underground biomass mainly distributed in 0—10cm soil layer,and it accounted for 70% of the total underground biomass.In addition,underground biomass reduced with the increase of soil depths.Variations in underground biomass were great in September than in June.