Knowledge Resource Center for Ecological Environment in Arid Area
| 内蒙古典型草原植物对降水量和降水间隔的响应 | |
| 其他题名 | Reponses of Plant Species in Inner Mongolia Typical Steppe to Changes in Precipitation Regimes |
| 刘宏德 | |
| 出版年 | 2012 |
| 学位类型 | 硕士 |
| 导师 | 潘庆民 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 水分是干旱半干旱区草原植物生长发育第一位的限制性资源，草原生态系统是陆地生态系统中对降水波动最为敏感的系统。大气环流模型（GCMs）预测未来高纬度地区降水量增加，同时极端降水或干旱事件发生频次增加，降水间隔将延长。但是迄今为止，关于降水量增加和降水间隔延长对我国草原生态系统会产生怎样的影响，我们的认知还相当有限。草原群落是由不同的植物种组成的，物种水平的响应对于我们深刻认识群落和生态系统水平的响应至关重要。为此，我们在内蒙古典型草原选择9个植物种，就它们对降水量增加和降水间隔延长的响应进行了研究，以期为揭示全球变化背景下草原植物的响应对策和生态系统演变的机理提供依据。\n本实验在完全控水的防雨棚中进行。降水量设置了27年平均降水量和平均降水量增加50%两个处理；降水间隔设置了3天1次（生长季发生频次最高的时间间隔）和15天1次（延长5倍的时间间隔）两个处理。9个植物种从功能型上分属多年生根茎禾草、多年生丛生禾草、一年生植物和灌木半灌木4个功能群；从优势度上包括建群种、优势种和常见种；从光合型上包括C3植物和C4植物。测定内容包括土壤温度、水分和养分动态、植物的生长速率和生物量动态、资源分配动态和植物的光合动态等。主要结论如下：\n1）降水量和降水间隔对土壤因素的影响\n降水量增加对大多数植物盆钵的土壤温度影响不显著，部分半灌木盆钵和一年生植物盆钵的土壤温度显著升高。降水间隔的延长对大多数植物盆钵土壤温度的影响不显著。\n降水量增加对C4植物（糙隐子草、木地肤、狗尾草和灰绿藜）盆钵土壤水分的影响显著高于C3植物种的盆钵。降水间隔对所有植物盆钵的土壤含水量均产生了显著影响。\n降水格局对半灌木盆钵土壤无机氮库的影响比对草本植物盆钵土壤无机氮库的影响更为显著，对一年生草本植物盆钵土壤无机氮库的影响比对多年生草本植物盆钵土壤无机氮库的影响要大，对多年C4丛生禾草盆钵土壤无机氮库的影响对多年生C3丛生禾草盆钵土壤无机氮库的影响要大。\n2）降水量和降水间隔对草原植物光合生理特性的影响\n从生长季的平均值看，降水量增加，多年生丛生禾草的净光合速率显著升高，多年生根茎禾草和一年生植物的净光合速率没有显著变化；西伯利亚羽茅的气孔导度显著升高，其它物种的气孔导度没有显著变化；大针茅的水分利用效率显著降低，其它物种的水分利用效率没有显著变化。\n从生长季的平均值看，降水量增加50%、降水间隔延长到15d的处理草原植物的光合速率的变化更为显著。多年生植物对降水间隔延长的响应较一年生植物更为强烈，不同多年生植物对降水间隔延长的响应并不一致。\n3）降水量和降水间隔对草原植物生物量的影响\n生长季前期，增加降水量使大多数物种生物量显著增加，延长降水间隔则使大多数物种生物量显著降低，地上生物量和地下生物量对降水量和降水间隔的改变在整个生长季中最为敏感。\n生长季中期，地上生物量和地下生物量对降水量的改变最不敏感。\n生长季后期，地上生物量和地下生物量对降水间隔的改变最不敏感。增加降水量使大多数物种地上生物量显著增加，延长降水间隔则使部分物种地下生物量显著降低，降水量的影响远大于降水间隔的影响。\n \n关键词：典型草原植物；降水量；降水间隔；土壤因素；光合生理特性；生物量 |
| 英文摘要 | Water is the primary limiting resource for grassland plant species in the arid and semiarid regions. Grasslands are the most sensitive ecosystems to the variability of annual precipitation among terrestrial ecosystems. General circulation models (GCMs) have predicted that, in high-latitude areas, precipitation amount will increase with the frequency of extreme precipitation events increasing and the drought intervals between precipitation events prolonged. However, we are still lack of the information about the effects of increasing precipitation amount and intervals on grassland ecosystems in China. Because plant community is composed of different plant species, species-level responses to changing precipitation regimes can help us understand the underlying mechanisms of community-level changes. Therefore, we chose 9 plant species and examined their responses to the changes in precipitation amount and in intervals between precipitation events. \nOur experiment was conducted in six rain-out shelters at the Inner Mongolia Grassland Ecosystem Research Station Chinese Academy of Sciences (IMGERS) in 2009. For precipitation amount, two levels, 249.1 mm and 373.65 mm (+50%), were used. The former is based on mean precipitation amount of treatment period (from June 1 to September 28) of 27 years (1982-2008) and the later is based on the prediction of IPCC (2007) that the precipitation amount in this area will increase. For precipitation pattern, two intervals between precipitation events, 3 d and 15d, were selected. The 3-d interval is the most frequent interval in growing season of 26 years (1982-2007) and 15-day interval represents extremely dry period. Nine plant species were selected, which belong to 4 functional groups (perennial rhizomatous grasses, perennial bunchgrasses, annuals, and semi-shrubs). They also represent a spectrum of species dominance in natural communities of typical steppe, from dominant species, subdominant species, common species and rare species. C3 and C4 plants were also considered. Soil temperature, soil water and soil inorganic N were measured to determine the changes of soil environments following changed precipitation regimes. Plant growth, biomass production and photosynthetic parameters were examined for determining the responses of 9 plant species. The key findings are as follows: \n1. Effects of changed precipitation regimes on soil parameters \nThe effects of changed precipitation regimes on soil temperature differed significantly among the pots with different species. The soil temperature was significantly affected by changed precipitation amount for 3 species and by changed precipitation intervals for 1 species. Increased rainfall amount affected the content of soil volumetric water in pots with C4 species more than those with C3 plant species. In contrast, precipitation intervals significantly altered the content of soil water for all plant species. \nThe content of soil inorganic N in pots with semi-shrubs was significantly affected by precipitation, compared with those planted herbs. The content of soil inorganic N in pots with annual herbs was significantly affected by precipitation, compared with those planted perennial herbs. \n2. Effects of changed precipitation regimes on plant photosynthesis \nWith the increase of rainfall amount, the photosynthetic rate of perennial bunchgrasses increased significantly, while that for perennial rhizomatous grasses and annuals exhibited no significant change. With the increase of precipitation intervals, perennials responded more significantly than annuals.\n3. Effects of changed precipitation regimes on plant biomass production\nAt the beginning stage of growing season, the biomass for most species increased significantly with the increase of precipitation amount. By contrast, the biomass for most species decreased significantly with the increase of precipitation intervals. For grassland plant species, this stage is the most sensitive period in biomass production to changing precipitation regimes. \nAt the middle stage of growing season, neither aboveground biomass nor belowground biomass was significantly influenced by changes in precipitation amount. \nAt the last stage of growing season, neither aboveground biomass nor belowground biomass was significantly influenced by changes in precipitation intervals. The aboveground biomass of most plant species increased significantly with the increase of precipitation amount, while the belowground biomass of some species reduced significantly with the increase of precipitation intervals. In total, plant biomass production was more sensitive to precipitation amounts than precipitation intervals.\nKey Words: Typical steppe; Precipitation regimes; Biomass production; Soil moisture; Soil nutrients; Photosynthesis |
| 中文关键词 | 典型草原植物 ; 降水量 ; 降水间隔 ; 土壤因素 ; 光合生理特性 ; 生物量 |
| 英文关键词 | Typical steppe Precipitation regimes Biomass production Soil moisture Soil nutrients Photosynthesis |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院植物研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287164 |
| 推荐引用方式 GB/T 7714 | 刘宏德. 内蒙古典型草原植物对降水量和降水间隔的响应[D]. 中国科学院大学,2012. |
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