为探讨不同载畜率下短花针茅(Stipabreviflora)种群的时空变异性特征及差异,本研究于2020年7-9月以荒漠草原建群物种短花针茅为研究对象,分析了对照(无牧)、轻度放牧、中度放牧和重度放牧等不同载畜率下的短花针茅出现频率、种群多度、相对多度及其时空变异性,并运用地质统计学软件进行平面空间分布模拟.结果表明:随着载畜率增大,短花针茅种群多度增加(P＜0.05),但群落总多度随载畜率增大而呈现出先增加后降低的趋势;在9月时,与对照相比,放牧造成短花针茅种群变异性显著降低(P＜0.05),但不同月份间短花针茅种群变异性无显著差异;通过对7月与9月的短花针茅种群空间分布进行平面模拟发现,在9月时,与对照相比,放牧造成短花针茅种群分布相对均匀,使得其种群变异性降低.综上,在长期放牧过程中,短花针茅种群趋向于均匀分布.

以天然草地为对照(CK),通过野外调查取样,对不同弃耕年限下植物群落生产力、盖度、高度、密度及多样性等指标进行分析.结果 表明:弃耕5a时,植物群落主要以一、二年生植物为主,其生产力占群落生产力的87.13％;随弃耕年限增加,弃耕地物种丰富度增加,主要以多年生禾草为主;弃耕15a时,多年生禾草物种丰富度与天然草地相近,但总丰富度与生产力仍显著低于天然草地(P＜0.05).此外,弃耕5a时,植物群落生产力与物种多样性存在显著正相关关系(P＜0.05);但弃耕15a草地和天然草地的生产力与物种多样性间无显著相关关系.

We conducted an experiment to test the characteristics and differences of the spatial distribution of constructive species Stipa breviflora at different scales under different stocking rates in the S. breviflora desert steppe in Siziwang Banner, Inner Mongolia. The spatial distribution of S. breviflora under four treatments (control, light grazing, moderate grazing, and heavy grazing) at different scales (small scale as 1 m×1 m and mesoscale as 5 m×10 m) were analyzed. The results showed that the population density of S. breviflora at mesoscale in the control and light grazing was significantly lower than that at the small scale. Grazing significantly increased the population density of S. breviflora in the meso- and small scales. At the small scale, the population distribution of S. breviflora in the control, light grazing, moderate grazing, and heavy grazing treatments conformed to linear, exponential, exponential and exponential models, respectively, and Gaussian, exponential, Gaussian and exponential models at mesoscale fitted by semi-variance function. The spatial distribution pattern at small scales in the control was simple and better but was more complex and poorer under the heavy grazing. At the mesoscale, it was simple and better under the heavy grazing but complex and poor under the moderate grazing. The spatial heterogeneity of S. breviflora population reduced and were more uniform under the moderate and heavy grazing at meso- and small scales. In addition, the trend of population distribution in the enclosure, moderate and heavy grazing were generally the same, while light grazing showed inconsistent trend at different scales.

为探究不同载畜率对荒漠草原群落建群种与优势物种间的关系及其空间分布的影响,于2020年7-9月在内蒙古四子王旗短花针茅荒漠草原进行野外调查,以建群种短花针茅及优势种无芒隐子草和冷蒿为研究对象,设置不放牧对照（CK）、轻度（LG）、中度（MG）和重度放牧（HG）载畜率水平（分别放牧0、4、8和12只羊）,结合常规方法与地统计学方法分析建群种及优势种出现频率、多度、种间关系强度及空间分布特征。结果表明:1)与CK相比,LG下冷蒿出现频率仅在7月显著降低了50.55%（P＜0.05）,而MG和HG在7-9月均显著降低（P＜0.05）,7-9月平均降低77.76%和97.53%;而不同处理及月份下短花针茅和无芒隐子草出现频率无显著差异（P＞0.05）。2)与CK相比,各处理在7-9月时短花针茅种群多度均显著增加（P＜0.05）,LG、MG和HG分别在7-9月平均增加37.34%、75.72%和99.32%;冷蒿种群多度均显著降低（P＜0.05）,分别降低61.26%、66.32%和99.31%;无芒隐子草除LG在9月无显著变化外,各处理在7-9月时种群多度均显著增加（P＜0.05）。3)短花针茅与无芒隐子草主要表现为亲和关系,而在9月时从CK的亲和关系转化为HG的竞争关系;短花针茅与冷蒿主要表现为竞争关系,放牧未改变其种间关系。4)短花针茅与无芒隐子草对冷蒿的作用强度较大,而冷蒿对短花针茅和无芒隐子草的作用强度较小。5)模拟9月物种间空间分布发现,CK中短花针茅种群多度随无芒隐子草种群多度增加而增加,随冷蒿种群多度增加而呈降低的趋势;HG中冷蒿种群多度不随短花针茅与无芒隐子草的变化而变化,但随着无芒隐子草种群多度增加,短花针茅种群多度整体上呈波动下降的趋势,表明短花针茅与无芒隐子草之间的关系由CK中的亲和关系转变为HG下的竞争关系。综上,放牧会改变物种的种群多度及物种间的关系。