Knowledge Resource Center for Ecological Environment in Arid Area
| 科尔沁沙地沙丘植物群落对降雨特征改变的响应 | |
| 其他题名 | Response of amanthium to altering rainfall regimes in Horqin Sand Land, north of China |
| 岳祥飞 | |
| 出版年 | 2016 |
| 学位类型 | 博士 |
| 导师 | 张铜会 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 全球变暖正在改变着区域的降雨特征，而降雨特征的改变将对陆地生态系统产生重要的影响。由于水是干旱半干旱环境最重要的限制资源，所以干旱半干旱生态系统被认为可能是对降雨特征变化最敏感的生态系统。本论文以半干旱沙地——科尔沁沙地为例，以通过长期监测数据分析和降雨控制试验相结合的方法研究了降雨特征变化对沙丘植物生长、群落结构与功能的影响，以期了解沙地植物生态系统结构与功能对未来降雨特征改变的潜在响应，为土地资源的可持续利用及管理提供理论依据。主要的结果和结论如下： （1）分析了科尔沁沙地沙漠化较为严重的奈曼旗43年（1971~2013年）的降水数据。结果表明，该地区平均降水量为338.8 mm，年降水量无明显的变化趋势。5-9月降雨量占全年降水量的85.32%，从2001年有缓慢增加的趋势，同时降水量的年际变率也呈增加的趋势。高频的小降雨事件是该地区降雨事件的主要组成部分，而低频率的大降雨事件是总降雨量的主要贡献者。生长季降雨日数以每10年2.16 d的速率在减少，降雨事件的分布有极端化的趋势，意味着强降雨事件和干旱事件频率将会增加。（2）分析了两种典型沙丘植物群落地上生物量、物种丰富度10年（2005~2014）的变化与同期降水特征的关系。结果表明，不同沙丘植物群落对降水变化的敏感性不同，以多年生灌木和草本植物为主的固定沙丘植物群落，地上生物量和物种丰富度与年降水量有显著正相关关系；以一年生植物为主的丘间低地植物群落地上生物量和物种丰富度与年降水量无显著相关性，而与5~8月的降雨特征有关。降雨频率和强度对丘间低地地上生物量的影响可能要强于降雨总量，但研究并没有得出地上生物量与降雨频率、强度的相关关系。（3）通过降雨控制试验调查了不同降雨特征（如高频率小降雨事件和低频率大降雨事件）对一年生植物生长的影响。结果发现，总降雨总量不变，随着降雨次数的减少、单次降雨强度的增加，一年生植物的地上、地下生物量和高度显著增加。例如，当降雨次数26次降至10次时，单次降雨量从8.37 mm升至21.76 mm，丘间低地一年生植物的地上显著增加；当降雨次数从12次降至6次、单次降雨量从15 mm升至30 mm时，流动沙丘一年生植物的地上、地下生物量均显著增加。但是，降雨间隔期的延长同样会影响一年生植物的生长。例如，降雨间隔期从16 d延长至32 d时，流动沙丘一年生植物的地上、地下生物量又显著降低。（4）通过降雨控制试验调查了自然降雨特征改变对一年生植物群落的结构与功能的影响。结果发现，总降雨量不变，单次降雨强度增加和降雨间隔期延长的极端降雨特征显著降低了一年生植物群落的地上生物量、植物高度、盖度、物种组成及多样性指数。如当降雨次数从自然条件下的23次降至8次时，一年生植物群落的地上生物量、盖度和高度显著降低，而当降雨次数降至5次时，降雨间隔期从9.7 d升至29.3 d时群落的地上生物量、植物高度、盖度、Shannon-Winner指数和物种丰富度均显著降低。（5）通过降雨控制试验调查了短期极端干旱事件（30 d无降雨发生）对一年生植物群落结构与功能的影响。结果发现，短期极端干旱事件显著降低了植物盖度、物种数和地上生物量，增加了植物地下/地上生物量比。但短期极端干旱事件对一年生植物群落的影响程度依赖于其发生的时间，例如，发生在4月的极端干旱事件对植物地上生物量的影响没有达到显著水平；4、5月的干旱事件对植物群落的盖度的影响并没有达到显著水平；4、7月的干旱事件对物种数的影响也未达到显著水平。 降雨分布特征（强度和频率）对科尔沁沙地一年生植物群落结构与功能的影响要强于总降雨量。以高频率小降水事件为主的多变的降雨类型对维持半干旱沙地生态系统一年生植物群落的生产力和物种多样性有重要的作用。大降雨事件频率的增加会促进一年生植物的生长，增加群落的生产力，但当降雨间隔期超过了一定的阈值则会抑制一年生植物的生长，降低群落生产力、改变群落的结构。因此，未来降雨特征的改变可能会加剧沙地一年生植物的干旱胁迫，影响沙丘生态系统的稳定性，减缓沙地沙漠化逆转的速率。 |
| 英文摘要 | Regional precipitation regime is altering by global warming, which will have significant impacts on terrestrial ecosysytems. Because water is the most limiting resource, arid and semi-arid ecosystems are likely to be highly responsive to future precipitation variability. However, the effects of precipitation variability on semi-arid ecosysytems remain less understanded. Combining the analysis of long-term mornitoring data with precipitation manipulation experiments, the goal of my dissertation is to understand how altering precipitation regime will affect stucture and function of amanthium in Horqin Sand Land, a semi-arid desert ecosysytem, North China, and provide theoretical basis for susutainable utilization and management of limited land resources. The results and conclusion as follows:(1) The 43-year (1971~2013) precipitation data of Naiman Banner, southeast Horqin Sand Land, was analysized. The results showed that mean rainfall from May to September was 291.9 mm, accounting for 85.32% of annual precipitation (338.8 mm), and tended to increase since 2001. Although rainfall was dominated by small rainfall events (<10 mm) with short rainfall intervals (<10 d), the large ranfall events with low frequency was the major contributor to total rainfall amount. The rain days tended to decrese at the rate of 2.16 d per 10 y. The distribution of rainfall in time tended to be extremelization, which indicated that the frequency of heavy rainfall events and short-term extreme drought is increasing.(2) The correlation between above-ground biomass (AGB), species richness (SR) of two amanthiums on different biotopes (sand dune and lowland) and precipitation characteristics during 10-year (from 2005 to 2014) was analysized. The results showed that the amanthium on sand dune was dominated by perennial plant species, and the AGB, SR was positively correlated with annual precipitation; while amanthium on lowland was dominated by annual plant species, and AGB and SR had significant correlation with rainfall characteristics of growing season (from May to August), rather than annual precipitation. The effects of rainfall patterns on annual plant communities may be more important than rainfall amount.(3) A rainfall manipulation experiment was carried out to investigate the effects of different rainfall patterns (e.g. small rainfall event with high frequency and large rainfall event with low frequency) on growth of annual plants. The results showed that, independent of total rainfall amount, the rainfall patterns played significant effects on growth of desert annuals. Under a constant amount of total rainfall, the aboveground biomass (AGB), belowground biomass (BGB), plant cover, plant height, and plant density of lowland annuals increased with an increase in rainfall size. The AGB, BGB and plant cover of annual plant of mobile sand dune increased when the size of rainfall events increasing from 15 mm to 30 mm, However, when number of rainfall events decresed from 6 to 3, the AGB, BGB and plant cover of agriophyllum squarrosum decreased significantly, although the size of single rainfall event increase from 30 to 60 mm.(4) A rainfall manipulation experiment was carried out to understand the effects of novel extreme rainfall regime on structure and function of annual plant community on fixed sandy land. The results showed that the rainfall regime characterized with intensified rainfall events and extended rainfall intervals significantly decreased AGB, plant height, plant cover and species diversity index of annual plant community, although total rainfall amount was consistant. For example, when number of rainfall events decreased from 23 to 8, the AGB, plant height and plant cover decreased significantly, and species richness and Shannon-Winner index also decresed when number of rainfall events decreased to 5. (5) A rainfall manipulation experiment was carried out to understand the effects of short-term extreme drought event (30 d without rain) on structure and function of annual plant community on fixed sandy land. The results showed that the short-term extreme drought events decreased AGB, plant cover and species richness of annual plant community on fixed sandy land, while increased the BGB/AGB ratio. However, the extent of the impacts largely depended on timing of extreme drought event. For example, extreme drought event in April had no significant effect on AGB, plant cover and species richness. Consequently, distribution of rainfall events (frequency and size) had more significant effects on structure and function of plant community than total rainfall amout. The current rainfall regime characterized by small rainfall events with high frequency play a important role on productivity and species diversity of amanthium. The increase in frequency of large rainfall event will promote the growth of annual plants and increase the productivity of amanthium, but extended event-interval inhibited the growth of annual plants, reduced productivity of amanthium, and influenced the structure of the community. The altering rainfall regime may affect the stability of sand land ecosystem and slow the reversal of desertification. |
| 中文关键词 | 降水变化 ; 极端降雨事件 ; 极端干旱事件 ; 一年生植物 ; 科尔沁沙地 |
| 英文关键词 | Precipitation variability Extreme rainfall regime Extreme drought events Annual plant community Horqin Sand Land |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287711 |
| 推荐引用方式 GB/T 7714 | 岳祥飞. 科尔沁沙地沙丘植物群落对降雨特征改变的响应[D]. 中国科学院大学,2016. |
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