两类植物型沙丘上植物群落的异同及其对沙丘形态的响应

为探究相同环境条件下发育的两类植物型沙丘上植物群落的异同点,以及相异点与沙丘形态的关系,对毛乌素沙地南缘盐碱地上相间分布的抛物线形沙丘和白刺灌丛沙丘分别进行形态学、植物群落学及土壤理化性质的调查分析。结果显示:抛物线形沙丘的水平尺度虽为白刺灌丛沙丘的12-23倍,但两类沙丘上物种数相当,其植物分属12科31属39种和12科30属33种,均以菊科、藜科、禾本科、豆科植物为主(占70%以上),其中共有植物17种,群落相似度0.66;两类沙丘上的群落建群种不同,优势种的重叠度较低,抛物线形沙丘的不同部位共统计到7个植物群丛,可分为沙生植物群落和喜湿耐盐碱群落,白刺灌丛沙丘上均以白刺为建群种,油蒿、冰草、雾冰藜、沙蓬、狗尾草为主要优势种;沙丘形态造成其不同部位风沙活动及土壤水分、PH值和全盐含量的差异是两类沙丘上植物群落相异的重要影响因素。

Similarities and differences of the plant communities on two vegetation-dunes and their responses to dune morphology

The morphology, vegetation, and soil physical and chemical properties of two vegetation-dunes located in different areas of the southern margin of the Mu Us Sandy Land were investigated. The aims of the study were to examine the similarities and differences of plant communities between parabolic dunes and Nitraria tangutorum nebkhas under the same environmental conditions, and to elucidate the relationship between plant community differences and dune morphology. The horizontal scale of the parabolic dunes was 12-23 times greater than that of the nebkhas, whereas the number of species on the two dune types was equivalent. The plants on parabolic dunes and N. tangutorum nebkhas comprised 12 families, 31 genera, and 39 species, and 12 families, 30 genera, 33 species, respectively, with the plants mainly belonging to four families:Asteraceae, Chenopodiaceae, Gramineae, and Leguminosae (more than 70%). There were 17 mutual species and the similarity index of the plant communities was 0.66, although there were differences in the constructive species and there was a lower degree of overlap of the dominant species. Seven plant associations were identified and could be classified into the psammophyte community and the saline-alkali-tolerant community on different parts of the parabolic dunes. In contrast, N. tangutorum was the only constructive species of the nebkha plant community, and the dominant species were Artemisia ordosica, Agropyron cristatum, Bassia dasyphylla, Agriophyllum squarrosum, and Setaria viridis. The spatial variability in soil moisture, pH, total salt content, and intensity of sand-drift activities caused by dune morphology promoted the differences in plant communities between parabolic dunes and N. tangutorum nebkhas.