Effects Of Artificial Interference On Plant Diversity And Productivity In Maqu Degraded Alpine Meadow

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.