Knowledge Resource Center for Ecological Environment in Arid Area
| 人工固沙植被建群种植物生长动态对降水波动的响应 | |
| 其他题名 | Responses of growth dynamics of artificially re-vegetated constructive plant species to precipitatio |
| 张浩 | |
| 出版年 | 2015 |
| 学位类型 | 博士 |
| 导师 | 王新平 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 摘要 在全球变暖影响下，全球及区域降水格局正在或将要发生改变，极端干旱、极端降雨时间发生频率增加，这将对陆地生态系统产生深刻影响。降水是干旱区荒漠生态系统过程和功能的最重要限制因子，受降水格局变化会影响，干旱荒漠区土壤水分、植物生长、群落组成、结构、物种多样性、生产力都将发生改变。为探讨荒漠生态系统对未来降水格局变化的响应，2013~2014年，在沙坡头沙漠试验研究站人工植被恢复区，选取不同生活型植物物种为研究对象，根据生长季内（5~9月）每次降雨量，进行不同梯度的人工模拟降雨实验（减雨50%、减雨25%、自然降雨、增雨25%、增雨50%、增雨100%），研究了不同植物覆盖下土壤水分、植物生长、一年生草本群落对生长季降雨波动的响应。主要结论如下： （1）沙坡头地区生长季降雨量在不同年份、不同月份时间变异性都较大。生长季平均降雨量为137.2 mm，平均降雨频次为24.5次，变异系数分别为38.2%和21.4%。生长季月降雨量分配不均，时间变异性较强，多年月降雨量平均变异系数为68.3%。沙坡头地区生长季降雨多以间隔5日内的＜5 mm小降雨事件为主，发生频次占总降雨频次的52.6~66.7%之间。＜5 mm的降雨事件对降雨量贡献不大，仅占总降雨量的14.3~19.9%之间。＞10 mm以上降雨频次占总降雨频次的16.8%~27.6%，占总降雨量的48.7%~65.5%，是生长季降雨量的主要贡献者。 （2）在干旱荒漠人工植被恢复区，降雨波动、地上覆盖植物物种形态和用水策略显著影响土壤含水量变化。油蒿灌丛低矮、茎叶密集呈垫状对灌丛下土壤遮阴性好，而柠条灌丛较高大，呈倒卵形对灌下土壤遮阴性差，所以整个生长季不同深度土壤含水量油蒿灌丛较柠条灌丛高。由于油蒿根系分布较柠条浅，对0~60 cm 深度土壤水分利用较柠条高，致使生长旺盛期6~8月油蒿灌丛0~60 cm深度土壤含水量波动性较柠条灌丛高。在降雨量、降雨频次较高的7月，0~60 cm深度土壤含水量都随降雨量增加而增高，6月和8月0~40 cm深度土壤含水量增加而增高，9月仅增雨100% 增高了0~40 cm深度土壤含水量，其他降雨处理土壤含水量无差异。 （3）由于不同生活型植物物种在物候、形态、生理等特性存在差异，造成生长对降雨波动的响应显著不同。 半灌木油蒿对生长季降雨波动敏感性高于灌木柠条。2013、2014年生长季不同降雨处理对灌木柠条新枝累积生长量无显著影响，2013年增雨100% 显著促进了半灌木油蒿新枝累积生长量，2014年减雨50% 处理显著降低了油蒿生长季累积生长量。2013年5~7月增雨处理对灌木柠条新枝生长没有显著影响，而对于半灌木油蒿增雨100% 处理显著促进了6月和7月新枝生长，增雨50% 处理显著促进了7月新枝生长；减雨50% 处理显著降低了柠条7月新枝生长，而对油蒿新枝生长影响不显著。2014年5~8月增雨处理对灌木柠条新枝生长没有显著影响，而增雨100% 处理显著促进了半灌木油蒿5月和6月新枝生长；减雨25% 和减雨50% 处理显著降低了柠条和油蒿6月新枝生长，同时减雨50% 处理还降低了油蒿7月新枝生长。生长季不同降雨波动对灌木柠条株高、冠幅生长没有显著影响。生长季增雨100% 显著促进了半灌木油蒿株高、冠幅生长，减雨50% 显著降低了油蒿株高、冠幅生长。 一年生禾本科物种小画眉对生长季降雨波动敏感性高于非禾本科优势物种刺沙蓬。增雨100% 处理显著促进了小画眉6月和7月株高生长量， 降低了小画眉8月株高生长。刺沙蓬各月株高生长不受增雨影响，减雨50% 降低了刺沙蓬7月和8月株高生长， （4）经过多年演替，在沙坡头人工植被恢复区灌丛下及灌丛间广泛分布着一年生草本植物片层，主要物种有：小画眉、刺沙蓬、虫实、雾冰藜、狗尾草、虎尾草、地锦、沙蓝刺头、沙米。其中小画眉、刺沙蓬为优势物种。一年生植物片层物种组成、结构、物种多样性及生产力往往受生长季、年际降雨波动影响。 增加100% 降雨量能显著增加禾本科物种小画眉、狗尾草、虎尾草种群数量。而非禾本科一年生物种种群数量受降雨波动影响不显著。一年生植物片层盖度随降雨量增加而增加，增加25%、50%、100% 降雨量显著增加一年草本植物群落总盖度，减少50% 降雨量显著降低了群落盖度。 降雨波动影响一年生植物片层物种多样性。增加100% 降雨量在整个生长季能维持较高的物种多样性和物种均匀度。减雨50% 降低了对干旱胁迫极端敏感的优势物种小画眉种群数量，增加了群落物种多样性和均匀度。 在平水年2013年，一年生植物地上部分生物量与生长季降雨量呈线性增加趋势。丰水年2014年，降雨量在255 mm以下一年生植物地上部分生物量与生长季降雨量呈线性增加趋势，当降雨量超过255 mm后地上部分生物量呈线性下降趋势。 |
| 英文摘要 | Abstract Changes in Earth’s surface temperatures are expected to affect the precipitation patterns of global and regional, and increase higher frequencies of extreme precipitation events and longer drought periods. These alterations could have important consequences on terrestrial ecosystems. Precipitation is the chief limiting factor for the processes and functions of desert ecosystems. The soil moisture, plant growth, species composition, structure and production of communities, would be altered by precipitation patterns changing in desert ecosystems. Artificial rainfall simulation experiments under 5 rainfall gradients were conducted upon desert plants of different life forms from 2012 to 2013 in revegetated desert of Shapotou Desert Research and Experement Station. According to the individual rainfall amounts in the growing season of 2013, rainfall amount was reduced by 25% and 50%, and increased by 25%, 50% and 100%, respectively, with natural rainfall as the control. We mainly aimed to assess the responses of soil moisture under different bushwood, plant growth, annual herbaceous communities to rainfall changes in growing season. The main results of the study is as fllows. (1) The rainfall amounts have a stronger variation whether between each month and interannual in Shapotou area. Average annual rainfall amount and rainfall frequency was respectively 137.2 mm and 24.5 in growing season, and the coefficient of variation was respectively 38.2% and 21.4. From 2002 to 2012, the average coefficient of variation monthly rainfall amount was 68.3% which indicate monthly rainfall was uneven distributed. Frequency of smaller rainfall events (＜5 mm) and intervals within 5 days are very higher in growing season, which is main characteristics of rainfall in Shapotou area. The frequency of smaller rainfall events (＜5 mm) accounted for 52.6~66.7% of total rainfall events form 2002 to 2012. But the contribution ratio of smaller rainfall events(＜5 mm) was very low for annual total rainfall amount, accounted for 14.3-19.9% of annual total rainfall amount only. The frequence of more than 10 mm rainfall events accounted for 16.8%~27.6% of total rainfall frequency, accounted for 48.7%~65.5% of total annual rainfall amount. More than 10 mm rainfall events was the most importent contributory for annual rainfall amount. (2) Precipitation fluctuation, morphological characteristics and water use strategy of plant significantly affect soil moisture in arid revegetated desert. The morphological characteristics of Artemisia ordosica is low cusion and branches is dense. Stems and leaves densely shade soil under the shrubs and reduce evaporating of soil moisture. But Caragana korshinskii is higher than Artemisia ordosica and crown is obovate, which characteristics is no shading function for soil under shrubs. So the soil moisture under Artemisia ordosica were always a little higher than under Caragana korshinskii throughout growing season. Artemisia ordosica roots distribute shallower at soil layer than Caragana korshinskii, so consuming water amount from depth soil layer of 0~60cm is much more than Caragana korshinskii. These different water use strategy increasing fluctuation of soil moisture under Artemisia ordosica in vigorous growth period from June to August. Due to rainfall amount and frequency is so more than the other month at July, the siol moisture in depth of 0~60cm increased with rainfall amount increasing during July. At June and August, the soil moisture in depth of 0~40cm increased with rainfall amount increasing. At September, Rainfall increased by 100% significantly enhanced soil moisture in depth of 0~40cm, but other treatment no variation. (3) Different life forms plant have variation characteristcs of phenology, morphology, physiology, these would affect the plant growth response to precipitation fluctuation. Subshrub Artemisia. ordosica has a higher sensibility to precipitation fluctuation than shrub Caragana korshinskii. Different artificial rainfall simulation treatmen weren’t significantly affect total growth at the end of growing season from 2013 to 2014. Increased rainfall by100% significantly promoted the new branch total growth of A. ordosica, in 2013, and reduced rainfall by 50% significantly reduced the new branch total growth. Increased rainfall treatment hadn’t affect significantly new branch growth of C. korshinskii from May to July in 2013, but increased rainfall by100% significantly promoted new branch growth of A. ordosica, during June and July. Increased rainfall by 50% significantly promoted new branch growth, and reduced rainfall by 50% significantly reduced the new branch growth during July. Increased rainfall treatment hadn’t affect significantly new branch growth of C. korshinskii but increased rainfall by100% significantly promoted new branch growth of A. ordosica during May and June in 2014. Induced rainfall by 50% reduced significantly the new branch growth of C. korshinskii and A. ordosica during June. Induced rainfall by 50% reduced significantly the new branch growth of A. ordosica during July in 2014. Precipitation fluctuation hadn’t affect significantly plant height and crown breadth growth of C. korshinskii. Increased rainfall by100% promoted plant height and crown breadth growth of A. ordosica. Induced by 50% reduced significantly the plant height and crown breadth growth of A. ordosica. (4)There are distributed extensively annual herbaceous species between and under bushwood after series successing. Main species include: Eragrostis poaeoides, , Salsola ruthenica, Bassiadasyphylla,Corispermum declinatum, Setaris Viridis Beauv, Chloris virgate, Euphorbia humifusa, Echinops gmelinii, Agriophyllum squarrosum. E. poaeoides and S. ruthenica are dominate species in all species. The composition, structure, diversity and productivity of annual herbaceous communities are frequently affected by precipitation fluctuation of annual and interannual.Increased rainfall by100% significantly increased population density for grass species including E. poaeoides, S. Viridis Beauv., C. virgate. But precipitation fluctuation coulden’t affect other herbaceous population density. The coverage of annual herbaceous communities incread with rainfall amount increasing, Increased rainfall treatments increased significantly the coverage of annual herbaceous communities. Reduced rainfall by 50% reduced significantly the coverage of annual herbaceous communities. Precipitation fluctuations affect the diversity of annual herbaceous communities. Increased rainfall by100% maintained higher diversity and evenness throughout growing season. Reduced rainfall by 50% reduced population density of E. poaeoides which are extremely sensitive for drought stress and increased diversity and evenness of herbaceous communities. Aboveground biomass of annual herbaceous communities was positive linear correlation with rainfall amount in growing season in 2013. Aboveground biomass of annual herbaceous communities were positive linear correlation with rainfall amount when was under 255mm, but it was negative linear correlation when total rainfall amount was above 255mm. |
| 中文关键词 | 荒漠生态系统 ; 降水波动 ; 土壤含水量 ; 新枝生长量 |
| 英文关键词 | Desert ecosystem Precipitation fluctuation Soil moisture New branch growth |
| 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/2XILL650/287523 |
| 推荐引用方式 GB/T 7714 | 张浩. 人工固沙植被建群种植物生长动态对降水波动的响应[D]. 中国科学院大学,2015. |
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