鄂尔多斯高原风蚀沙化梁地克隆植物的分布及其与物种多样性的关系

 采用样线法和点样法对鄂尔多斯风蚀沙化梁地上的植物进行了调查，研究了梁地上克隆植物的分布、克隆植物在群落中的重要性及其与群落物种多样性之间的关系。结果表明：1）在梁顶的典型草原植物群落和梁底的滩地盐生植物群落中克隆植物的物种丰富度较高，而在梁坡的沙生植物群落中较少，非克隆植物物种在梁顶出现频率较高，在梁坡和梁底较少；密集型克隆植物物种丰富度的变化与非克隆植物相同，游击型克隆植物在梁顶植物群落中没有出现，在梁坡群落中也很少，而在梁底的滩地中较多。2）梁底群落中克隆植物的重要值高于梁顶和梁坡群落中克隆植物的重要值，梁顶与梁坡群落中非克隆植物的重要值高于梁底群落中非克隆植物的重要值；在梁坡与梁底群落中，克隆植物的重要值都高于非克隆植物的重要值，而在梁顶群落中克隆植物与非克隆植物的重要值之间无差异；梁顶与梁坡群落中密集型克隆植物的重要值高于梁底群落中密集型克隆植物的重要值，而游击型克隆植物的重要值在梁底群落中较高；在梁顶与梁坡群落中，密集型克隆植物的重要值分别高于游击型克隆植物的重要值，而在梁底群落中，密集型克隆植物的重要值低于游击型克隆植物的重要值。3）梁顶的典型草原植物群落中，群落物种多样性随非克隆植物的重要值、克隆植物的重要值、密集型克隆植物的重要值的变化趋势相同，都为抛物线型。梁坡的沙生植物群落中，群落物种多样性与非克隆植物的重要值呈正相关，而分别与克隆植物和密集型克隆植物的重要值呈负相关。梁底的滩地盐生植物群落中，群落物种多样性与非克隆植物的重要值呈正相关，而与克隆植物和游击型克隆植物的重要值呈负相关。

CLONAL PLANTS ALONG THE SANDY HILL-SLOPE IN ORDOS PLATEAU AND RELATION OF THEIR IMPORTANCE TO PLANT SPECIES DIVERSITY

We investigated the distribution of clonal and non_clonal plants along the sandy hill_slope in Ordos Plateau, using the line intercept method and the point method. One_way ANOVA was used to compare the difference of species richness and importance of plants with different growth forms among communities along the sandy hill_slope. We used the regression analysis method to analyze the relation of species diversity to importance of clonal plants in the communities. Species richness of clonal plants was higher in the ridge summit and the mid_slope, while lower in the foot_slope. The same trends were found for non_clonal plants, their species richness in the ridge summit and mid_slope was higher than that in the foot slope. Variation of species richness of phalanx clonal plants was similar to that of non_clonal plants. Guerilla clonal plants were absent in the ridge summit and few in the mid_slope, while abundant in the foot_slope. The importance of clonal plants in the foot slope was higher than in the ridge summit and the mid_slope. The importance of non_clonal plants in the foot slope was lower than in the ridge summit and the mid_slope. The importance of clonal plants was higher than the non_clonal plants in the mid_slope and the foot slope, while there was no such a difference between them in the ridge summit. The importance of phalanx clonal plants in the ridge summit and the mid_slope was much higher than that in the foot slope. In contrast, the importance of guerilla clonal plants in foot slope was much higher than that in ridge summit and mid_slope. The importance of phalanx clonal plants was higher than that of guerilla clonal plants in both the ridge summit and the mid_slope, while in the foot slope, the importance of guerilla clonal plants was higher than that of phalanx clonal plants. In the ridge summit, the relations of community plant species diversity to importance of clonal plants, importance of non_clonal plants as well as importance of phalanx clonal plants were parabola. In the mid_slope, plant species diversity increased with increasing importance of non_clonal plants, while it decreased with increasing importance of clonal plants as well as importance of phalanx clonal plants. In the foot_slope, plant species diversity was positively correlated to the importance of non_clonal plants, and negatively correlated to the importance of clonal plants as well as importance of guerilla clonal plants. Our results confirmed that clonal growth in plants is adaptive in general under stressed conditions, and clonal plants are more important in stressful habitats. There are marked differences between phalanx and guerilla clonal plants in their optimal locations along the sandy hill_slope. Phalanx clonal plants are more abundant and more important in drier habitats. In contrast, guerilla clonal plants tend to be more abundant and more important in wetter habitat. This suggested that phalanx clonal plants seem to have strong ability to grow under stressed environments. In the community located in ridge summit, Shannon_Wiener index increase and then decrease with increasing importance of clonal plants. In mid_slope and foot_slope communities, Shannon_Wiener index decrease with increase importance of clonal plants owing to their strong spreading ability.