【作者】 陈子萱；

【导师】 牛俊义；

【作者基本信息】 甘肃农业大学 ， 作物生态生理， 2008， 博士

【摘要】 近年来青藏高原草地沙化日趋严重,位于黄河第一弯的甘肃省玛曲县是黄河径流重要的汇集区和黄河上游至源头的重要水源涵养区。补充黄河水量约达45%。但由于人口和牲畜的增加,掠夺式经营使草场退化严重,湿地萎缩。全县近90%的天然草地出现了不同程度的退化和沙化,其中沙化面积达5×104hm2以上,且每年以10.8%的速度蔓延。研究人工扰动对高寒沙化草地植物多样性和生产力的影响,以及草地植物群落特征和演替状况,对玛曲县高寒草地生态环境恢复和沙漠化防治有重要意义。本论文采用围栏、施肥和补播等方法研究了人工扰动对高寒沙化草地生态系统中植物多样性与生产力,以及草地植物群落生态位特征的影响,主要取得了以下结果:1施肥使高寒沙化草地植物群落高度明显增加,氮肥、磷肥和有机肥混合施肥效果最好,可使群落高度增加76.75%。施肥使植物个体增高增壮,使得植被盖度整体上增加,3种肥料混合施肥盖度可增加7%。在高寒沙化草地补播禾草后,对草群高度影响不大,垂穗披碱草、中华羊茅和草地早熟禾混播使平均高度增加了26%。补播明显增加了植被盖度,其中3种禾草混播可使盖度增加7%。施肥和补播使沙化草地高度和盖度增加,可以防止沙化草地进一步沙化,对高寒沙化草地的恢复起到重要的作用。2施肥使物种丰富度显著下降,草群密度减小,3种肥料混施可使物种数比对照减少了17.24%,密度减少30.09%。施肥使Pielou均匀度指数增大,Simpson指数和Shannon-Wiener指数减小。补播使物种丰富度增加,草群密度都明显增大,补播草地早熟禾使物种数增加了8.08%,混播中华羊茅和垂穗披碱草使密度增加了39.65%。补播后各处理Pielou均匀度减小,Simpson指数,Shannon -Weiner指数也减小,其中单播中华羊茅,和混播中华羊茅和垂穗披碱草显著减小。施肥和补播都使草地植物多样性下降。3施肥后使草地地上生物量比对照显著增加,3种肥料混施使地上生物量增加150.33%。施肥后生产力的增加主要是因为禾草类生物量的增加,禾草类占到地上总生物量的50%左右。禾草类生物量的增加,使草地可食牧草的比例增加,也提高了草地的经济价值和营养价值。补播后地上生物量比对照显著增加,3种禾草混播后地上生物量增加了55.74%左右,禾草类占到总地上生物量的50%以上,补播禾草后,草地群落以禾本科为主要的产量构成因素,草地的经济价值也得以提高。施肥和补播对提高草地生产力有明显的作用,有利于高寒沙化草地的恢复,也有利于高寒草地生态环境保护。4沙化草地群落结构不稳定,存在高度异质性,与其它草地群落结构不同,多样性-生产力没有明显的相关关系。施肥后多样性-生产力是U型相关关系,R2达到0.73;但补播后多样性-生产力是近似U型关系,R2仅为0.31,相关性不高。5玛曲高寒沙化草地当前的优势种是异针茅,围栏、施肥和补播都没有改变异针茅的优势地位。乳浆大戟和高山唐松草等作为高寒沙化草地的主要杂草,具有很强的生态适应性和竞争能力,它们与优势种异针茅和亚优势种紫羊茅等在生态环境资源的利用上相似程度较高,在群落的演替过程中起着重要作用。经过围栏、施肥和补播两年后,禾草得到较好的生长,种间竞争由杂类草之间的竞争,以及杂草与其它种群的竞争逐渐转变为杂类草与禾草之间的竞争。随着禾草类个体数,盖度和高度的增加,禾草竞争力增强,对其它种群造成抑制,杂类草减少,草地的利用价值得以提高。人工扰动措施围栏、施肥和补播禾草都能提高高寒草地的质量,是提高退化高寒草地生产力的有效手段,可以在退化高寒草地大量推广。更多还原

【Abstract】 In recent years desertification of Tibetan plateau alpine meadow has become increasingly serious. Maqu County of Gansu Province located in the first bend of the Yellow River, which is the main catchment area and the important water sources conservation areas of upper Yellow River, it added Yellow River water about 45%. However, nearly 90% of the natural meadow has appeared degradation and made wetlands shrinking in Maqu County for increasing in population and livestock, the predatory business to serious degradation of meadows. Desertification area of more than 5×10~4hm~2, and the annual increasing rate is 10.8%. It was the important meaning to restore its ecological environment and alpine meadow and control desertification. It had also important significance that study on artificial disturbance on plant diversity and productivity, characteristics and succession situation of plant communities in Maqu alpine desertified meadow. The research had been done on plant diversity and productivity of the ecological system and the relationship between them, meadow communities niche characteristics and artificial disturbance experiments by methods of enclosure, fertilization and fertilization in Maqu alpine desertified meadow, we drew the following conclusions:1. The research showed heights of plant communities in alpine meadow desertification increased significantly, mixed fertilization treatments of nitrogen, phosphate and organic fertilizer was the best effect, which increased 76.75% of communities height. Fertilizing treatments had made the plants individual strong, vegetation cover increasing. The treatments of three fertilizers could increase coverage of 7%.Interseeding of grasses had little effect on grasses height, Average height of Elymus nutans, Festuca sinensis keng and Poa pratensis L. increased 26%. Interseeding significantly increased the vegetation coverage. Coverage of three mixed interseeding grasses increased 7%.2. Fertilization made species richness dropped significantly, reduce the density of grass group. Species of nitrogen, phosphate and organic fertilizer treatments decreased number 17.24% less than that of non-fertilizing treatment and density of nitrogen, phosphate and organic fertilizer treatments redued 30.09% Fertilization made Pielou evenness index increased, while Simpson index and the Shannon-Wiener index decreased, plant diversity decreased. Interseeding increased species richness and grass groups density significantly. The density added 39.65% by mixed interseeding Festuca sinensis keng and Elymus nutans. After interseeding, Pielou minished, Simpson index and Shannon-Weiner index also decreased, which single seeding Festuca sinensis keng and mixed interseeding Festuca sinensis keng and Elymus nutans reduced evidently. Fertilization and interseeding made plant diversity declined.3. Above-ground biomass significant increased after fertilizing. Above-ground biomass of mixed fertilization treatments for nitrogen, phosphate and organic fertilizer added 150.33%. After fertilization, productivity increasing was due to grasses biomass increasing, grasses biomass accounted for the total biomass of about 50%. Grasses biomass increased, the ratio of edible forage grass increase, also enhanced the economic value of meadow nutritional value. After interseeding, Above-ground biomass also significant increased than control, Above-ground biomass of mixed interseeding Elymus nutans, Festuca sinensis keng and Poa pratensis L. increased about 55.74%.Grasses accounted for the total biomass of more than 50%. This showed grasses formed of the main production factors, the economic value of meadow also be improved.We had taken measures of artificial disturbance improved the productivity of meadow, and controlled desertification in alpine meadow.4. Desertified meadow community structure was instability, it had heterogeneous and had different community structure. There were no obvious correlativity. Diversity - productivity is U-shaped relationship after fertilization. But after interseeding Diversity - productivity is similar to U-shaped relationship, the calibration graphs of the method were not linear.5. Stipa aliena was the current dominant species in Maqu alpine desertification meadow. Fencing, fertilizer and interseed didn’t change different podcasts have not changed dominant species position of Stipa aliena.However Euphorbia esula and Thalictrum alpinum as the main forbs, which had strong ecological adaptability and competitiveness, they played an important role in the community succession.After two years treatments of Fencing, fertilizer and interseed, grasses grew better, the competition is mainly between the forb and grass competition. With the grasses individual categories, coverage and a high degree increasing, grasses will inevitably posed major advantage groups, this improved utilization value of alpine desertification meadow. Interseeding grasses and fertilization could improve the meadow quality, increase the productivity in degradation alpine meadow, which can widely generalize in degraded alpine meadow.更多还原