呼伦贝尔沙化草地不同生态修复阶段植物群落特征研究

Study on the characteristics of plant communities in different ecological restoration stages of Hulun Buir sandy grassland

  • 摘要: 人工植被修复是减缓草地沙化与生态重建的重要措施,理解不同修复阶段的沙地植物群落演替特征及其影响因素有利于沙地植被的持续修复。以呼伦贝尔市甘珠尔沙地植被修复为例,分别调查了修复9、11、13、15 a共4个不同修复阶段植物群落结构特征及土壤理化性质,探索甘珠尔沙地人工修复植物群落演替变化及其对环境因子的响应。结果表明:研究区共发现植物42种,隶属于17科35属。草本39种,以菊科、禾本科、蔷薇科和豆科为主;灌木3种,为豆科和菊科。不同修复年限物种数变化依次表现为28种(15 a)、25种(13 a)、19种(9 a)和16种(11 a)。各年限内多年生草本物种数均明显高于一年生和一/二年生植物。草本与灌木在不同修复阶段其优势种、地上生物量及物种多样性均存在波动变化,具体表现为草本植物中地梢瓜(Cynanchum thesioides)、虫实(Corispermum hyssopifolium)、披碱草(Elymus dahuricus)、糙隐子草(Cleistogenes squarrosa)、羊草(Leymus chinensis)与狗尾草(Setaria viridis)的优势度较高,灌木以小叶锦鸡儿(Caragana microphylla)为主要优势种。草本植物地上生物量和总盖度整体呈现波动增加的趋势但差异不显著。灌木总盖度15 a显著高于9 a,地上生物量整体呈现逐渐增加的趋势,表现为11、13、15 a均显著高于9 a。不同修复阶段的物种多样性指数在草本中无显著差异,但在灌木层表现为15 a显著高于9 a。随机森林模型表明,沙化草地的修复过程中气候及土壤因子对植物群落结构特征贡献度存在差异。土壤总氮含量、总钾含量、有机质含量、年降水量和年均风速是影响甘珠尔沙地草本植物多样性的主导因子,其中除年均风速外均为正相关。因此,建议在沙地植被修复中适当增加含氮、钾、有机质等营养物质的肥料,促进沙化生态系统的植物群落结构重建与多样性的恢复。

     

    Abstract: Artificial vegetation restoration is an important measure to slow down grassland desertification and ecological reconstruction. Understanding the succession characteristics and influencing factors of plant communities in different restoration stages is conducive to the sustainable restoration of vegetation in the sandy land. Taking the vegetation restoration of Ganzhuer sandy land in Hulun Buir as an example, the plant community structure characteristics and soil physical and chemical properties at different restoration stages in 9, 11, 13 and 15 years were investigated respectively, and the succession changes of artificial restoration plant communities and their responses to environmental factors were explored. It was found that 42 species of plants were found in the study area, belonging to 17 families and 35 genera, including 39 species of herbs, mainly Compositae, Gramineae, Rosaceae and Leguminosae. There were 3 kinds of shrubs, including Leguminosae and Compositae. The number of species in different recovery years varied from large to small, and the order was 28 species (15 a) > 25 species (13 a) > 19 species (9 a) > 16 species (11 a). Within each year, the number of perennial herbaceous species was significantly higher than that of annual and biennial plants. In different restoration stages, the dominant species, aboveground biomass and species diversity of herbaceous and shrub fluctuated. Specifically, among the herbaceous plants, Cynanchum thesioides, Corispermum hyssopifolium, Elymus dahuricus, Cleistogenes squarrosa, Leymus chinensis and Setaria viridis had higher dominance, and Cynanchum thesioides was the main dominant species of shrub. The aboveground biomass and total coverage of herbaceous plants did not change noticeably, but the overall trend was fluctuating and increasing. The total coverage of shrub in 15 a was significantly higher than that in 9 a, and the aboveground biomass showed a trend of gradual increase, which was significantly higher in 11, 13, 15 a than in 9 a. The species diversity index of the herbaceous had no significant difference in different restoration stages, and the species diversity of shrub layer was significantly higher in 15 a than in 9 a. The random forest model showed that the contribution of local climate and soil factors to the characteristics of plant community structure was different in the restoration process of desertification grassland. Soil total nitrogen, total potassium, organic matter, annual precipitation and average annual wind speed were the dominant factors affecting herbaceous diversity in Ganzhuer sandy land, and all of them were positively correlated except the average annual wind speed. Therefore, it was suggested to appropriately increase fertilizer containing nitrogen, potassium, organic matter and other nutrients in the sandy land vegetation restoration, so as to promote the plant community structure reconstruction and diversity restoration in the desertification ecosystem.

     

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