河西走廊绿洲外围沙化草地固沙造林效果研究

Study on the effect of dune fixation afforestation on desertification grassland around the oasis edge in Hexi Corridor,Gansu Province

通过对流动沙丘固沙造林效果的对比研究,结果发现:未固沙造林的沙丘,丘间低地是以芦苇和赖草为优势种的原生群落,沙丘迎风坡植被稀疏,不形成植物群落,而实施固沙造林技术20年后的沙丘,虽丘间低地群落组成成分变化不大,但流动沙丘被完全固定,中下部形成以引入固沙灌木柠条锦鸡儿、花棒为优势种的人工植物群落,植物种类增加,生产力提高,草地生态系统得到有效恢复。固沙造林沙丘与未固沙造林沙丘相比,丘间低地群落高度增加51.6%,产草量增加12.6%,盖度增加4.7%,多度无变化,密度提高15%,物种丰富度指数提高25%,均匀度指数提高34.8%;迎风坡下部群落高度增加87.1%,产草量增加13%,多度提高一个等级,密度增加15%,物种丰富度指数提高228%,均匀度指数提高22.8%;迎风坡中部群落高度增加453.7%,产草量增加64.5%,多度提高一个等级,密度增加128.9%,物种丰富度指数提高616%,均匀度指数提高33.3%;迎风坡上部植被非常稀疏,不形成群落,植株平均高度25.3 cm,产草量增加206.8%,多度提高一个等级,密度增加550%,物种丰富度指数提高800%,均匀度指数提高66.7%。

The effect of afforestation on moving sand dune was studied and the results showed that the dominant plants between untreated sand dunes were Phragmites commiunis and Leymus secalinus. The vegetation in the windward slope of sand dune was sparse. However, the moving sand dunes where the afforestation technique was applied for 20 years later were entirely fixed,though the composition of community had no visible change in the low lands between sand dunes. The introduced shrubs established into artificial vegetative community with the dominant species Caragana korshinskii and Hedysarum scoparium in the middle and lower part of sand dunes. The grassland ecosystem was rehabilitated effectively with the increasing variety of vegetation and the increasing productivity. Compared with untreated sand dunes, the height of community, forage yield, coverage, density,species abundance index and evenness index in the low lands between treated sand dunes increased by 51.6 %, 12.6%, 4.7 %, 15 %, 25 % and 34.8 % respectively. No changes were found in species composition. In the low part of windward slope of sand dunes,the community height increased by 87.1% ;the forage yield increased by 13~ ;the variety number increased by one grade and density increased by 15% ;the species abundance index increased by 228% and the evenness index increased by 22.8%. In the middle part of windward slope of sand dunes,the community height increased by 453.7 % ;the forage yield increased by 64.5%;the species number increased by one grade and density increased by 128.9% ;the species abundance index increased by 616% and the evenness index increased by 33.3 % ;In the upper part of windward slope of sand dunes,the vegetation was very sparse and could not form community. The mean height of vegetation was 25.3 cm. The forage yield increased by 206.8 % ;the species number increased by one grade and density increased by 550 % ; the species abundance index increased by 800% and the evenness index increased by 66.7%.