科尔沁沙地西缘两种沙丘上盐蒿种群空间点格局研究

Study on Spatial Point Pattern of Artemisia halodendron Population on Two Sand Dunes in the Western Margin of Horqin Sandy Land

摘要: 研究科尔沁沙地西缘主要固沙灌木盐蒿(Artemisia halodendron)种群的空间分布格局和空间关联性，可以为该区域固沙灌木保护和防风固沙提供科学依据。沿地形在科尔沁沙地西缘半固定沙丘和流动沙丘上分别设置40 × 160 m和40 × 148 m的样方，采用点格局分析方法，结合不同零模型综合分析0~20 m尺度盐蒿物种的数量结构特征、空间分布格局及种内关联。研究结果表明：1) 基于异质泊松模型，半固定沙丘上各生长发育阶段的盐蒿种群聚集程度较流动沙丘强。半固定沙丘盐蒿个体在研究尺度上以聚集分布为主，随着尺度的增大，聚集程度逐渐减弱且趋于随机分布；流动沙丘盐蒿种群则表现出在小尺度上聚集，在大尺度上随机的空间分布格局。2) 基于泊松聚块模型，盐蒿种群在半固定沙丘的中小尺度上表现出正向偏离模型，在流动沙丘的部分尺度上表现出负向偏离模型，其余尺度内符合模型。嵌套双聚块模型进一步检验表明，在0~20 m研究尺度范围内，盐蒿种群在两种沙丘上均符合模型。3) 基于先决条件模型，两种沙丘上盐蒿种群个体间表现出相似的空间关联性。即幼株与营养株在中小尺度上呈正关联，其余尺度上无显著关联；幼株与生殖株以及营养株与生殖株在中小尺度上呈正相关，较大尺度上无显著关联。多种零模型检验表明，生境异质性和种子扩散限制是形成科尔沁沙地半固定和流动沙丘上盐蒿种群的空间分布格局的主要原因。

Abstract: The investigation of the spatial distribution patterns and spatial associations of the primary desert-stabilizing shrub, Artemisia halodendron, in the western margin of Horqin Sandy Land provides scientific evidence for the conservation and windbreak functions of this species. To achieve this, quadrats measuring 40 × 160 m and 40 × 148 m were established on semi-fixed and mobile sand dunes, respectively, along the terrain of the western margin of Horqin Sandy Land. Using point pattern analysis methods combined with various null models, the quantitative structural characteristics, spatial distribution patterns, and intra-specific correlations of Artemisia halodendron were analyzed at scales ranging from 0 to 20 meters. The results indicate that: 1) Based on the heterogeneous Poisson model, the aggregation intensity of Artemisia halodendron populations at different growth stages is stronger on semi-fixed sand dunes than on mobile sand dunes. On semi-fixed sand dunes, Artemisia halodendron individuals exhibit aggregated distributions at the research scale; however, as the scale increases, the degree of aggregation decreases, and the population distribution tends towards randomness. Conversely, on mobile sand dunes, populations display aggregated distributions at smaller scales but random spatial distribution patterns at larger scales. 2) Based on the Poisson cluster model, Artemisia halodendron populations on semi-fixed sand dunes positively deviate at small to medium scales, while they negatively deviate at certain scales on mobile sand dunes, with the remaining scales conforming to the model. Further validation using nested double-cluster models confirms that Artemisia halodendron populations in two sand dune habitats adhere to this model within scales of 0~20 meters. 3) Based on antecedent condition models, individuals of Artemisia halodendron populations in two sand dune habitats show similar spatial correlations: young plants positively correlate with nutrient plants at small and medium scales but show no significant correlation otherwise; similarly, young plants correlate positively with reproductive plants, as do nutrient plants with reproductive ones at small and medium scales, without significant associations observed at larger ones. Multiple null model tests indicated that habitat heterogeneity and seed dispersal limitation are the main reasons for the spatial distribution pattern of Artemisia halodendron populations on semi-fixed and mobile sand dunes in Horqin Sandy Land.