晋北农牧交错带草地生物量对短期放牧强度的响应

Response of Grassland Biomass to Short-term Grazing Intensities in the Agro-pastoral Ecotone in Northern Shanxi

放牧是草地的主要利用方式之一,适度放牧可维持草地的生产和生态功能。为探究不同放牧强度如何影响北方农牧交错带草地生物量,本研究依托2016年在山西典型农牧交错带建立的草地放牧试验平台,采用收获法监测了不同放牧强度干扰下植物群落优势种赖草生物量(Leymus secalinus Tzvel.biomass,L.s.B)、地上生物量(Aboveground biomass,AGB)和地下生物量(Belowground biomass,BGB)指标。结果表明:放牧降低了该地区群落地上现存生物量和地下生物量(P<0.01),提高了群落的根冠比(P<0.05);放牧影响优势种赖草生物量在群落地上生物量中的占比,与不放牧相比,轻度放牧和重度放牧对赖草生物量的影响大,而中度放牧的影响小。因此,放牧降低了群落的地上、地下生物量,但中度放牧对优势种赖草生物量的影响小,符合中度干扰假说,为农牧交错带草地科学管理和可持续利用提供理论依据。

Grazing is one of the main approaches of grassland utilization.Moderate grazing can maintain the production function and improve the ecological function of grassland.In order to explore how different grazing intensities affect grassland biomass in the northern agro-pastoral ecotone,in 2016 we set up an experimental platform with four grazing intensities in the typical agro-pastoral ecotone grassland of Shanxi.We used the harvest method to study the effects of different grazing intensities on the biomass of Leymus secalinus Tzvel.(L.s.B),aboveground and belowground biomass of the grassland community(AGB and BGB).The results showed that:grazing significantly reduced the AGB and BGB of the plant community(P<0.01),grazing increased the root to shoot ratio of the community(P<0.05);grazing also affected the proportion of the L.secalinus biomass in the AGB of the community.Compared with ungrazed treatment,the light and heavy grazing had greater impacts on the L.secalinus biomass,while that effect of the moderate grazing was insignificant.Therefore,short-term grazing would reduce the AGB and BGB of the plant community,but the moderate grazing had little impact on the L.secalinus biomass,which was consistent with the“Intermediate disturbance hypothesis”,and could provide scientific basis for the rational utilization of grassland and ecological protection in the agro-pastoral ecotone.