以四合木植物群落为研究对象,通过设置不同放牧强度:轻度放牧(LG)、中度放牧(MG)、重度放牧(HG)的控制试验,以及与无放牧(NG)对照,对四合木群落植物种类组成、物种多样性、生物量及种群更新情况进行研究。结果表明:1)随着放牧强度的增加,群落优势种四合木的重要值呈上升趋势,HG降低了草本群落中无芒隐子草、画眉草的重要值,提高了蒙古韭、骆驼蓬的重要值;2)与NG区相比,放牧处理降低了草本群落的高度、盖度、密度以及地上生物量,放牧处理下灌丛群落的高度、密度及地上生物量变化不显著,盖度呈先增后减的趋势;3)与NG区相比,放牧处理显著提高了草本群落的多样性指数、丰富度指数和优势度指数,显著降低了灌木群落的多样性指数;4)地上生物量与多样性指数、丰富度指数在各区呈线性增加的关系,与均匀度指数在NG、LG、MG区表现为正相关,在HG区表现为不相关,与优势度指数呈负相关;5)四合木种群实生苗密度在MG、HG区高于NG区。综上所述,四合木植物群落结构和功能受放牧行为的影响,其中草本群落对放牧行为的响应相较灌丛群落更为明显,因此适度放牧有利于控制草本群落,保护四合木种群。

This study focused on the Tetraena mongolica plant community,examining the effects of different grazing intensities light grazing(LG),moderate grazing(MG),heavy grazing(HG)and no grazing(NG)as the control,onplant species composition,species diversity,biomass,and population regeneration.1)As grazing intensity increased,the importance value of dominant species Tetraena mongolica in the community showed an upward trend.HG reduced the importance values of Cleistogenes songorica and Eragrostis pilosa in the herbaceous community,while increasing the importance values of Allium mongolicum and Peganum harmala.2)Compared to NG,grazing reduced the height,coverage,density and aboveground biomass of herbaceous communities.No significant changes in the height,density and aboveground biomass of shrub communities under grazing treatment,although the coverage showed a trend of initially increasing and then decreasing.3)Compared to the NG area,grazing significantly increased the Shannon-Wiener,Margalef and Simpson indices of the herbaceous community,while significantly reduced the Shannon-Wiener index of the shrub community.4)Aboveground biomass was positively correlated with the Shannon-Wiener and the Margalef indices in all areas.It was positively correlated with the Pielou index in NG,LG,and MG areas,but shows no correlation in the HG area.It was negatively correlated with the Simpson index.5)The density of seedlings of the Tetraena mongolica population was higher in the MG and HG areas compared to the NG area.In summary,the structure and function of Tetraena mongolica plant communities are affected by grazing behavior,with the herbaceous community showing a more significant response than the shrub community.Therefore,MG is beneficial for controlling the herbaceous community and protecting Tetraena mongolica populations.