Study on Effects of Improved Measures on Vegetation and Soil of Grassland
The research was carried out at the country of Taipusi, south of Xilingol Grassland of Inner Mongolia, for two years from 2007 to 2008. The objective of the experiment is to research the effect of different improved measures on the degraded grassland. There were four measures adopted: turf scarifying(H), turf scarifying and irrigation(H+G), fertilizer(N1:25kg/hm~2, N2:50 kg/hm~2, N3:75 kg/hm~2, N4:100 kg/hm~2 urea per year) and irrigation, fertilizer(S:75 kg/hm~2 urea per year) and none as control to research the effect and mechanism of these measures from the characteristic of individual, populations, community and soil, and according to these to choose a more suitable measure of the region and provide theory foundation. The results indicated:1. The height、coverage、density、and biomass of all species in community got the maximum at the middle of August. Some species such as Leymus chinensis and Agropyron crastatum were got the maximum at the middle of September because of the abundant rainfall in 2008 year.2. The treatment of turf scarifying can improve the soil condition of air and water content. The treatment of irrigation can increase the water content of the soil and the treatment of fertilization can improve the deficiency of soil nutrient. So all the treatments could be effectively improved the recovery of the degraded grassland. The height, coverage, density and biomass of the community were significantly improved in contrast to the control and the leaf indexes were increased.3. The different measures could be effectively improved the growth of all plants. And the species of Leymus chinensis, Agropyron crastatum, Pottentilla acaulis and Phlomis tuberose were more sensitive to the measures. The percentage in community and the important value of those were changed relatively obviously by different measures. The species of Leymus chinensis and Pottentilla acaulis are seperately the constrative and the dominant species in the community and according to the changes of both species and community and the nutrient of siol as indexes to evaluate the effects of the treatments.4. The measures of 50kg/hm2 urea could be the best to the growth of Leymus chinensis in two years.The height increased 64.42% and 45.14% separately in 2007 and 2008 years to the control. And the coverage also increased 40%, double to the control. The biomass of community increased 538.98% and 249.53% separately in two years and the important values increased from 0.21 to 0.45.5. The measures of 100kg/hm2 urea could be the most significant to the growth of Pottentilla acaulis in two years. The height increased 32.7% and 26.9% to the control in two years. The density and coverage also increased. The biomass of community increased 123.28% and 12.37% separately in two years and the important value increased 0.4 to the control in 2007 year. The important values of Leymus chinensis were lower than Pottentilla acaulis except in H+G and N2 treatment of two years.6. All measures could improved the plant growth in the community, and the height、density、coverage and the above ground biomass of the community were significantly promoted. N2 and N3 treatments were the most effective in contrast to others. The aboveground biomass increased 163.68% and 169.71% in August of 2007 year separately and 53.04% and 51.57% in September in 2008 year. The richness (S and Margalef index)、diversity index (Simpon index and Shannon-Weaver index)、LAI index and the ratio root: shoot were changed a lot in two years relating to many factors, so they were not contained in the indexes of evaluate the effects of treatments.7. In contrast to all measures, N2 treatment was the most significant way to improve the height、density、coverage、aboveground biomass and the important value of the Agropyron crastatum species and the same of Phlomis tuberose species by N3 treatment.8. The soil nutrient of N2 treatment was all enhanced. The total nitrogen content of 0-10 cm soil depth was increased 2.86% to the control. The total phosphorus content were increased 2.85%、13.76% and 12.75% separately in 0-10cm, 10-20cm, 20-30cm soil depth. The available nitrogen content were higher in 10-20cm and 20-30 cm soil depth to the control, increased 7.03% and 26.86% separately. The available phosphorus content increased 21.56%, 2.94% and 22.92% and organic matters content were increased 3.78%, 12.91% and 21.72% in every soil depth separately.9. In contrast of the effects of changes of fours species, community and soil nutrient, N2 treatment was the most significant effective. And the important values of Leymus chinensis were higher than Pottentilla acaulis in two years and became the dominant species in the community. The percentage of Agropyron crastatum in community was also increased. So in considering of the treatments effects and the value in use of the grassland, 50kg/hm2 urea and irrigation was the most effective way in the region.9. The plant growth coule be better in the early spring than increasing rainfall later by the contrast of H and H+G, S and N3 treatments.10. The period of flowering of species such as Koeleria cristata, Phlomis tuberose, Thalictum petaloideum and Allium anisopodium were changed in two years.11. The distribution of aboveground biomass and belowground biomass were changed in different treatments and the ratio root: shoot were lower than the control. There were no obvious relationships of the aboveground biomass, belowground biomass and the ratio root: shoot to the rainfall in growing seasons, but had some correlation to the last month average temperature. And the climate factors did not have the determine function to the effects of treatment.