Knowledge Resource Center for Ecological Environment in Arid Area
| 典型沙区土壤水分同位素特征及固沙植被水分来源研究 | |
| 其他题名 | Analysis of water moisture isotope characteristics and sand-fixation vegetation water sources in typical desert regions |
| 王艳莉 | |
| 出版年 | 2016 |
| 学位类型 | 硕士 |
| 导师 | 刘立超 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 植物固沙是防治沙害和构建风沙区生态屏障的重要措施。建国以来，我国在西部地区实施了一系列以植被建设为主的生态建设工程，对当地的水土流失和沙漠化等产生了积极的影响。但受严酷的生境条件限制，特别受有限水分的限制，一些早期栽植的固沙灌木逐渐退化，植被盖度大幅下降，严重影响沙区固沙植被的稳定性。土壤水分是影响固沙植被的主要因子，研究沙区土壤水分状况和固沙植被对土壤水分的利用模式，对建设合理稳定的固沙植被具有理论和实践意义。本研究以我国西北典型固沙植被区—腾格里沙漠东南缘（沙坡头）、毛乌素沙地南缘（盐池县）和古尔班通古特沙漠南缘（阜康）固沙植被为研究对象，以稳定同位素技术为主要研究手段，系统研究了不同固沙植被区降水、土壤水、地下水和植物水的稳定同位素组成（δ18O和δD）特征，并利用Iso-Source模型分析了固沙植被对不同深度土壤水分的利用比例，确定了不同深度土壤水和地下水对固沙植物的贡献及其季节变化，研究结果表明：一、在沙坡头固沙植被区，（1）降水δ18O值的变化范围较大，具有明显的季节变化规律。在生长季前期（4-6月）和生长季后期（9-10月）降水δ18O值处于较高水平；雨季降水δ18O值处于相对较低水平。该地区区域大气降水线方程：δD=7.88δ18O+7.12（R2=0.91，n=27），与全球大气降水线方程相比，斜率与截距均偏小，表明该区域降水过程中稳定同位素值受到了二次蒸发的影响。（2）在较大降水（18.4mm）后第一天，柠条对40-80 cm土壤水的利用率占56.1%，油蒿对20-60 cm土壤水的利用率占56.4%；降水后一周，柠条和油蒿都增加了对浅层土壤水的利用比例，其中，柠条对0-40 cm土层水分利用率增加了12.5%，油蒿对0-20 cm土层水分利用率增加了10%。（3）0-200cm土层内随土壤深度的增加土壤水δD值整体呈下降趋势，且具有明显的季节效应。浅层（0-40cm）土壤水δD值变化幅度较大，夏季土壤水δD值明显高于春季和秋季；中层（40-120cm）土壤水δD值波动较小，在较多降水补给后δD值有增加趋势；深层（120-200cm）土壤水δD值季节差异较小保持相对稳定的状态。（4）固沙植被柠条在4-7月份较为干旱的条件下主要利用浅层0-60cm的土壤水分，8-10月份土壤水分条件较好时主要利用40-100cm土壤水分。油蒿水分利用主要在0-60cm土层范围内，其中6-7月分主要利用0-30cm土层土壤水，而在8-10月份对60-100cm水分利用可达20%~30%。表明固沙植被可以通过改变水分利用策略，高效地利用有限的降水，从而避免和克服干旱所引起的水分胁迫。二、在盐池柠条固沙植被区，（1）浅层0-50cm土壤含水量波动较大；50-100cm土层土壤含水量随土层深度增加呈快速下降趋势；100-200cm土层土壤含水量较低且有缓慢增加的变化趋势；200-300cm深度土壤含水量处于较高水平且有趋于稳定的变化趋势。（2）随着林龄的增大，10-310cm土层土壤储水量呈先减少后增加的变化趋势。林龄 10a至20a间是土壤水分快速消耗时期；而林龄近20a至30a间土壤水分条件差异不大且有好转的变化趋势，其中对中层土壤水分的旱化持续增加，深层土壤水有所回升。（3）在植被生长旺盛季，10a林龄柠条主要利用0-50cm土壤水分；19a和28a林龄主要利用100cm土层以下土壤水，其中对100-200cm土层水分利用比例为55.8%和27.3%，对200-300cm土层的利用比例分别占38.7%和62.8%；自然恢复区柠条主要水分来源于60cm土层，利用比例占66.4%，对深层土壤水分的利用比例较小。表明随着林龄的增大对深层土壤水分的利用比例逐渐增加。三、在阜康梭梭固沙植被区，（1）0-40cm浅层土壤水δ18O值随土层深度和季节变化波动较大；40-100cm中层土壤水同位素值波动相对缓和，随土层深度增加呈减小变化趋势，δ18O值大小季节差异不大；100-300cm深层土壤水同位素值随土层深度增加变化较小且季节间差异不明显。（2）夏季，梭梭95.2%水分来源于深层土壤水及地下水；春季融雪后梭梭对浅层土壤水的利用比例较大为48.6%，中层土壤水所占比例为12.4%，深层土壤水及地下水的利用比例为和39%。因此，由冬季融雪和春季降水补给的浅层土壤水、深层土壤水及地下水是固沙植被梭梭可利用的重要水源。梭梭对不同水源利用的季节性变化是其对干旱环境的适应的表现。 |
| 英文摘要 | Revegetation is an important measure to combat the scourge of sand and build s ecological barrier in desert area. Since the founding of the China, a series of ecological construction projects focused on vegetation have been implemented to control soil erosion and desertification, which has a positive impact in the western region. However, due to the harsh habitat conditions, particularly the water limitation, some early sand-fixing shrubs gradually degenerated and vegetation coverage declined dramatically, seriously influencing the stability of sand-fixing vegetation. Soil moisture is the main factor for sand-fixing vegetation. Therefore, study of soil moisture conditions and plants uptake by soil moisture can offer theoretical and practical significance for constructing the reasonable and stable vegetation in desert area.In this study, we choose three typical vegetation areas of northwestern China- southeast edge of the Tengger Desert (Shapotou), the southern edge of the Mu Us sandland (Yanchi County) and southern edge of the Gurbantünggüt Desert (Fukang) for the study. Stable isotope technology is used as the main research method to analyze the characteristics of isotopic compositions (δ18O and δD) of precipitation, soil water, groundwater and plant xylem water in different vegetation areas and the Iso-Source model is then used to calculate water utilization ratio in different soil depths of the sand-fixing vegetation. Therefore, the contributions of groundwater and soil water at different depths to sand-fixing plants and its seasonal variation are determined.Main findings of this dissertation are summarized as follows:In Shapotou sand-fixing vegetation region, the two plants of Caragana korshinskii and Artemisia ordosica were chosen for study, the results show that: (1) an equation of local meteoric water line in Shapotou is δD=7.88δ18O+7.12 (R2=0.91). The value for rainfall δ18O varied during plant-growing season, which showed a higher values in the beginning and end of growing season, and a lower value in the peak of growing season. (2) The value for soil water δ18O in the upper layers varied dramatically and the variation become smaller when soil depths go deeper. Caragana korshinskill had a greater efficiency (56.1%) in utilizing soil water in 40-80cm layers. Artemisia ordosica had a utilizing efficiency of 56.4% in 20-60cm soil layers. One week after rain event, Caragana korshinskill and Artemisia ordosica showed a higher efficiency in upper soil water. Caragana korshinskill showed an increase of 12.5% in utilizing soil water in 0-40cm layer and Artemisia ordosicas showed an increase of 10% in utilizing soil water in 0-20cm layers. These results suggest that water utilizing efficiency in growing plants change dramatically after large rainfall events. (3) In soil profile of 0-200cm, soil water δD values have a downward trend with increasing of soil depth and have a significant seasonal effects. In shallow layer (0-40cm), soil water δD value has a larger changes in volatility, and summer soil water δD values were significantly higher than in spring and fall. In middle layer (40-120cm), soil water δD value is less volatile and δD values tend to increase after more precipitation recharging. In deep layer (120-200cm), seasonal variation of soil water δD value is smaller and that maintains a relatively stable state. (4) Under drier conditions ( April to July) Caragana korshinskill mainly uses of shallow layer (0-60cm) soil water. When the soil moisture conditions become better (August to October), Caragana korshinskill mainly uses soil moisture of 40-100cm. Artemisia ordosicas uptake water is primarily from the range of 0-60cm soil layer. Artemisia ordosicas mainly uses the 0-30cm layer soil water from June to July and then the uptake water can use up to 20% to 30% from the 60-100cm layer soil water (August to October). These variations may enable plants more easily to be adapted to arid and semi-arid environment. Therefore, this study provides important data for desert plantation and ecology-management.In the southern edge of the Mu Us sandland (Yanchi County), we choose three groups of different ages (10a, 19a, 28a) and natural restoration zone Caragana korshinskill, the results show that: (1) In shallow layer (0-50cm) soil moisture has a larger volatility variation. In 50-100cm layer soil moisture decreases rapidly with the increase of soil depth. In 100-200cm layer soil moisture content is lower and there is slowly increasing trend. In 200-300cm layer soil moisture is at a high level and there is the trend of stabilization. (2) With the increase of forest age, soil water storage of 10-310cm layer decreases first and then increases. Around 10a to 20a soil moisture is quickly consumed period. The difference of soil moisture conditions of forest age near 20a to 30a is not obvious and has an improved trend, in which the middle layer soil moisture drought continues to increase and the deep soil water has recovery. (3) In the vigorous vegetation growth season, Caragana korshinskill of 10a forest age mainly uses the 0-50cm layer soil moisture. Caragana korshinskill of 19a and 28a mainly uses soil water of the following 100cm layer, in which the ratio of soil water uptake of 100-200cm is 55.8% and 27.3%,respectively. And utilization ratio of 200-300cm layer accounts for 38.7% and 62.8%, respectively. At the natural restoration zone Caragana korshinskill uses soil moisture of 60cm soil layer and the ratio is 66.4%. It indicates that the utilization proportion of deep soil moisture increased with the age of the forest.In the southern edge of the Gurbantünggüt Desert (Fukang), the sand-fixing shrubs Haloxylon ammodendron is as the research object. The results show that: (1) In shallow layer (0-40cm), soil water δ18O values variation with soil depth and seasonal fluctuation is obvious. In middle layer (40-100cm), the fluctuation of isotope values is relatively slight and decreases with the increase of soil depth. In soil water of deep layer (100-300cm), isotopic values varied a little with the increase of soil depth and the seasonal variation was not obvious. (2) In summer, Haloxylon ammodendron mainly takes advantage of deep soil water and groundwater and the proportion accounts for 95.2%. In spring after the snow melting, the shallow soil water using ratio of Haloxylon ammodendron is 48.6%. The proportion of middle soil water is 12.4% and deep soil water and groundwater is 39%. Therefore, the shallow soil water recharged by snow melting and precipitation in spring, deep soil water and groundwater are the important water sources for Haloxylon ammodendron. Moreover, seasonal variations of water usage of Haloxylon ammodendron reflect its adaptation to this water-limiting desert environment. |
| 中文关键词 | 典型沙区 ; 固沙植被 ; 土壤水分 ; 稳定氢氧同位素 ; 水分来源 ; 水分利用策略 ; Iso-Source模型 |
| 英文关键词 | typical desert region， sand-fixation vegetation， soil moisture， hydrogen and oxygen stable isotopes， water sources， water-use strategy， Iso-Source model. |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生物工程 |
| 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/2XILL650/287691 |
| 推荐引用方式 GB/T 7714 | 王艳莉. 典型沙区土壤水分同位素特征及固沙植被水分来源研究[D]. 中国科学院大学,2016. |
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