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内蒙古典型草原群落和物种水平对降水变化的响应

发布时间:2018-06-18 14:31

  本文选题:草原生态系统 + 降水格局 ; 参考:《内蒙古大学》2015年硕士论文


【摘要】:当前人类活动的加剧显著地影响着全球大气循环的格局。多个大气循环模型预测:年际间降水波动增大、极端降水事件(如:极端干旱和强降雨)发生频率增加将是未来全球水分循环变化的主要特征。水分是干旱、半干旱区草原植物生长发育的限制性资源。而草原生态系统是陆地生态系统中对降水变化非常敏感的系统。迄今为止,关于降水变化对我国草原生态系统会产生怎样的影响,我们的认识还相当有限。研究群落与物种对降水变化的响应,对于我们深刻认识生态系统的响应至关重要。本实验依托中国科学院内蒙古草原站完全控水防雨棚实验平台,利用控制实验的手段,探讨了生长季不同降水总量和降水分布格局对内蒙古典型草原群落与物种水平的影响。取得的主要结论如下:(1)土壤平均含水量随着生长季降水量的增加而升高,表层(0-20cm)土壤水分的波动减小,总体水分波动增加;降水分配格局的改变虽然对土壤平均含水量没有显著影响,但是却增加了土壤水分的总体变异。(2)群落地上生产力随着生长季降水量的增加而增加,和土壤平均含水量之间存在显著的线性关系。生长季前期和中期的降水量比值为1:1时,群落地上生物量显著低于其他格局的处理。生长季降水量和降水格局的改变对地下生物量没有显著影响。(3)群落盖度随着生长季降水量的增加而升高,尤以增加生长季中期降水量的效果最为显著。生长季降水总量和降水格局对群落多样性没有显著影响;功能群之间比较发现,多年生丛生禾草和多年生根茎禾草生物量随着降水总量的增多而增加;多年生杂类草和一、二年生植物对降水总量的变化响应不显著。降水格局的改变对多年生丛生禾草、多年生根茎禾草、多年生杂草和一、二年生植物四个功能型组成均没有显著影响。(4)物种水平上,西伯利亚羽茅和大针茅的高度、盖度和多度随着降水总量的增加先增加后减小,生物量与土壤平均含水量之间存在着较好的线性关系;苔草的高度、盖度和多度和生物量在整个降水范围内并没有显著差异;羊草的高度、盖度、多度和生物量均随降水量的增加而增加,生物量与土壤平均含水量之间存在较好的线性关系。降水分配格局的变化对四个物种的高度、盖度、和密度没有显著影响,降水格局变化对西伯利亚羽茅和羊草的生物量均无显著影响。苔草和大针茅的生物量在前期与中期降水量之比为1:8的处理下显著高于其他处理水平。降水格局处理中四个物种的生物量与土壤平均降水量之间均无显著的线性关系。
[Abstract]:The aggravation of human activities has significantly affected the pattern of global atmospheric cycle. Several atmospheric cycle models predict that the increase of interannual precipitation fluctuation and the increase of the frequency of extreme precipitation events (such as extreme drought and heavy rainfall) will be the main characteristics of global water cycle changes in the future. Water is a restricted resource for the growth and development of grassland plants in arid and semiarid areas. Grassland ecosystem is very sensitive to precipitation change in terrestrial ecosystem. So far, our understanding of the impacts of precipitation changes on grassland ecosystems in China is rather limited. It is very important for us to study the response of communities and species to precipitation changes. Based on the experimental platform of the Inner Mongolia steppe station of the Chinese Academy of Sciences, the effects of different precipitation amount and precipitation distribution pattern on the level of typical grassland communities and species in Inner Mongolia were studied by means of control experiments. The main conclusions are as follows: (1) the average water content of soil increases with the increase of precipitation in growing season, but the fluctuation of soil moisture decreases and the fluctuation of total water increases with the increase of precipitation in the growth season. Although the change of precipitation distribution pattern had no significant effect on the average soil water content, it increased the total variation of soil water content. 2) the aboveground productivity of the community increased with the increase of precipitation in the growing season. There was a significant linear relationship between soil moisture content and soil water content. When the precipitation ratio of the early and middle growing season was 1:1, the aboveground biomass of the community was significantly lower than the treatment of other patterns. The change of precipitation and precipitation pattern in growing season had no significant effect on the underground biomass. The coverage of community increased with the increase of precipitation in growing season, especially in the middle of growing season. The total precipitation and precipitation pattern in growing season had no significant effect on community diversity. The results of functional group comparison showed that the biomass of perennial herbage and perennial rhizomatous grasses increased with the increase of total precipitation, and that of perennial hybrid grasses and I. The response of biennial plants to the change of total precipitation was not significant. The change of precipitation pattern had no significant effect on the height of the four functional types of perennial herbaceous grasses, perennial rhizomatous grasses, perennial weeds and first and second year plants. Coverage and abundance increased first and then decreased with the increase of total precipitation, and there was a good linear relationship between biomass and soil average water content, but there was no significant difference in height, coverage and abundance and biomass of Carex spp in the whole precipitation range. The height, coverage, abundance and biomass of Leymus chinensis increased with the increase of precipitation, and there was a good linear relationship between biomass and soil water content. The change of precipitation distribution pattern had no significant effect on the height, coverage and density of four species, while the change of precipitation pattern had no significant effect on the biomass of Siberian fescue and Leymus chinensis. The biomass of Carex lanceolata and Stipa grandis was significantly higher than that of other treatments when the ratio of precipitation was 1:8. There was no significant linear relationship between the biomass of the four species and the average precipitation in the precipitation pattern treatment.
【学位授予单位】:内蒙古大学
【学位级别】:硕士
【学位授予年份】:2015
【分类号】:S812

【参考文献】

相关期刊论文 前2条

1 江玉林;生物多样性及其保护[J];国外畜牧学(草原与牧草);1999年01期

2 龚道溢,韩晖;华北农牧交错带夏季极端气候的趋势分析[J];地理学报;2004年02期



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