切根和浅耕翻措施对退化草地生长季土壤性质及植物群落的影响

草地退化是我国主要生态问题之一,研究草地不同改良措施的生态效应对于科学有效地恢复草地生态系统具有重要意义。以切根、浅耕翻两种典型改良措施为对象,在内蒙古锡林郭勒盟毛登草原内蒙古大学生态学研究基地研究了两种改良措施对土壤硝化速率、羊草群落植物生物多样性和生物量的影响。结果表明:与对照相比,浅耕翻措施显著降低了土壤硝化速率(P0.05),切根措施对土壤硝化速率有提高效果,且土壤硝化速率呈现出明显的时间动态,土壤硝化速率6月份显著最高、9月份显著最低;浅耕翻措施显著降低了羊草群落植物多样性和生物量(P0.05),而切根处理则显著提高了羊草群落植物多样性(P0.05),切根处理对植物生物量提高有作用但效果不显著。研究结果表明不同草地恢复措施显著影响了土壤性质和植物群落,在短期内,浅耕翻措施不是草地恢复的有效措施,而切根处理有助于提高退化草地生物多样性。

Effects of root pruning and shallow plowing on soil properties and plant communities in deteriorated steppe

Grassland degradation is one of the main ecological problems in the arid and semi-arid areas of China. Nitrogen content, which is typically reflected by the mineralization rate of soil nitrate nitrogen, plays a very significant role in plant life in deteriorated steppe regions. The key to addressing the limitation of soil nitrogen content is determining how to increase the exchange speed of soil nitrate nitrogen mineralization using different ameliorative treatments. Furthermore, biomass, the accumulation of organic matter per unit leaf area, is also a vital evaluation factor for primary productivity. Species diversity, the index of which generally increases with an increase of biomass, is an indicator of ecosystem stability. The species diversity of deteriorated steppe communities reflects the restoration status of grassland and changes in soil physical and chemical properties. The aim of the present study was to provide a scientific basis for the development of deteriorated steppe restoration by determining the effective use of different ameliorative treatments. In this regard, we examined the effects of two typical ameliorative treatments, namely, shallow plowing and root pruning of deteriorated grassland, in Inner Mongolia in order to determine the effects of different treatments on soil properties (the mineralization rate of soil nitrate nitrogen) and the character of Leymus chinensis communities (biomass and biodiversity). The data was obtained at the research base of the School of Life Science, Inner Mongolia University of Mao Deng grassland, Xilin Gol, Inner Mongolia. The research focused on the relationship between different treatments and biodiversity, biomass, and the mineralization rate of soil nitrate nitrogen. Compared with the control treatment, our results indicate that the mineralization rate of soil nitrate nitrogen was reduced by shallow plowing (P < 0.05). This might be attributable to changes in soil structure and the natural habitat of most plant caused by shallow plowing, which often causes marked disturbance to the soil in the first and second years after plowing. The mineralization rate of soil nitrate nitrogen was increased by root pruning but the effect was not significant. This might be due to the reduction in certain species whose growth requires a high content of nitrite nitrogen, although the total biomass increased. The mineralization rate of soil nitrate nitrogen differed according to the time of year. The lowest nitrification rate was in June, whereas the highest was in September. Shallow plowing significantly reduced the diversity and biomass of the L. chinensis community, whereas root pruning significantly increased the diversity of this community (P < 0.05). This is because the growth of annuals is more rapid in seasons with high precipitation. Root pruning reduced the competition between short-lived plants and other plants. Accordingly, annuals could grow very well and increased in number. This might be closely related to the increase in biomass. Although the biomass of the L. chinensis community was incr eased by root pruning, the difference was not significant. The data show that different treatments have a marked impact on soil properties and biota. Furthermore, root pruning treatment, but not shallow plowing, contributes to the biodiversity of deteriorated steppe in the short term.