Knowledge Resource Center for Ecological Environment in Arid Area
| 荒漠河岸胡杨液流与叶水势特性研究 | |
| 其他题名 | Characteristics of Sap Flow and Leaf Water Potential of Populus euphratica in Desert Riparian Forest |
| 李小琴 | |
| 出版年 | 2014 |
| 学位类型 | 硕士 |
| 导师 | 张小由 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 水是影响干旱区生态环境的决定性因子，在有限的水资源条件下，准确计算各生态系统需水量是合理高效配置和利用水资源的前提条件。胡杨（Populus euphratica）是黑河下游荒漠河岸林生态系统的最主要建群种之一，它对于维护荒漠河岸林生态系统的健康稳定发展有重要作用，也是当地最重要的旅游资源。蒸腾作用是植物水分消耗的最主要方式，是植物水分吸收和运输的主要动力；植物叶片水势是液态水在植物体内流动的驱动力，它代表着植物水分运动的能量水平，是判断植物水分亏缺、衡量植物抗旱的重要指标，也是目前最常用的植物水分生理指标。因此，将胡杨的蒸腾耗水特性与水势特征结合起来可以更好地反映胡杨耗水特征与机制，也可以为区域生态需水量的估算提供一定的数据基础。\n 试验于2013年5-9月在黑河下游额济纳旗七道桥胡杨林保护区和阿拉善荒漠生态水文试验站内及其南向约800 m的胡杨林内进行，利用SF300茎流计对胡杨树干液流速率进行测定，结合边材面积-胸径关系对林分耗水进行初步估算。利用WP4露点水势仪对水文站内外胡杨在不同条件下的叶水势进行测定，结合利用LI-6400测定的光合、蒸腾等数据对叶水势变化特征进行探讨。通过研究，得到以下结论：\n 1) 液流速率日变化呈明显宽单峰形曲线；夜间存在液流上升现象，夜间平均液流速率为白天平均液流速率的的32%；液流速率与蒸腾速率、光合速率、气孔导度日变化之间均存在较好的拟合关系，R2依次为0.72、0.62、0.61。不同探针插入深度处的液流速率变化趋势一致，由外层到内层呈现“低-高-低”的变化趋势；最大液流速率位点在25 mm深度处；径向校正系数K=0.56。\n 2) 单株月耗水量由大到小依次为7月、8月、6月、9月和5月，对应的月耗水量依次为1421.04 L、1168.08 L、943.20 L、720.00 L、505.92 L，5-9月单株总耗水量为4758.24 L。边材面积-胸径最佳拟合模型为：As =1.522(DBH)1.479，R2=0.96；经耗水尺度扩展得到林分在5-9月总耗水量为370.90 m3，按林分总面积折合为247.27 mm水深，日平均耗水为1.62 mm。\n 3) 各个月份典型晴天胡杨叶水势日变化趋势相似，基本呈“V”形曲线，最小值几乎都出现在13:00；叶水势在阴天没有明显的变化规律且日变化幅度很小；胡杨叶水势月变化基本呈先上升后下降趋势，各月平均值为-2.43 MPa。不同树龄胡杨叶水势日变化规律相同，但水势值存在一定差异，表现为：ψ老龄<ψ中龄<ψ幼龄；叶片着生部位越高叶水势越低；卵圆形叶水势值整体稍高于披针形叶。Ta、RH和VPD与叶水势的多元线性拟合方程为：Ψ=-0.171VPD-0.05Ta-0.01RH，R2=0.99；低的土壤含水量对应的叶水势也较低；叶水势与蒸腾速率和光合速率间均存在较好的拟合关系，R2分别为0.78和0.85。胡杨和柽柳(Tamarix ramosissima)叶水势日变化趋势基本相同，柽柳水势值明显低于胡杨，且变幅更大，胡杨叶水势日均值为-2.58 MPa，日变幅为1.33 MPa，柽柳日均值为-5.96 MPa，日变幅为2.76 MPa，二者都属于低水势忍耐脱水型植物。 |
| 英文摘要 | Water is the crucial factor of ecological environment in arid areas. It is the precondition to calculate accurately the water demand of every ecosystem for reasonable and efficient utilization of water resources under limited water supply. Populus euphratica is the main plantation species of desert riparian forest ecosystem in the lower reaches of Heihe River. It plays a significant role in maintaining healthy and stable development of desert riparian forest ecosystem, and is the most important tourism resource of Ejin Banner. Transpiration is the main water consumption way of plant and is the major impetus of water uptake and transportation of plant. Leaf water potential is the driving force of liquid water flowing in plant. It represents the energy level of plant water movement and is an important indicator to detect water deficit and measure drought resistance of plant. It is also the most widely used water physiological indicator of plant. \n The study was carried out between May and September 2013 in Qi Daoqiao Euphratica Forest Protection Zone, the Alxa Desert Eco-hydrology Experimental Research Station (Alxa Station) and the euphratica forest about 800m south of Alxa Station. Combining the sap flow velocity data measured by SF300 stem flow gauge and the relationship between SA and DBH, we discussed the variable characteristics of sap flow velocity and evaluated the water consumption of the euphratica forest stand. Combining the leaf water potential data measured by WP4 Dewpoint Potential Meter and the photosynthetic and transpiration data measured by LI6400, we discussed the variable characteristics of leaf water potential in Populus euphratica. According to the study, we got the main conclusions as flows: \n 1) The diurnal variation of sap flow showed a wide mono-peak curve. Sap flow still uptook at night and its average velocity was 32 percent of that of the day. There are highly significant correlations between sap flow velocity and transpiration rate, photosynthetic rate and stomatal conductance，and the determination coefficients were 0.72, 0.62 and 0.61, respectively. The variation tendency of sap flow velocity was similar under different insertion depth. It presented a “low-high-low” trend from the outer part of sapwood to the inner part. The largest sap flow velocity appeared at 25mm insertion depth. The radial correlation coefficient K was 0.56. \n2) The water consumption of the standard tree of different months from high to low was July, August, June, September and May, and the values were 1421.04L, 1168.08L, 943.20L, 720.00L and 505.92L, successively. The whole water consumption between May and September was 4758.24L. The best fitting model of sap area and DBH (diameter at breast hight) is As =1.522(DBH)1.479, R2=0.96. According to the upscaling of water consumption, the whole water consumption of the forest stant between May and September was 370.90 m3, which can be converted to 247.27 mm water depth according to the forest stand area. And the average daily water consumption of the stand was 1.62 mm.\n3) The diurnal variation tendency in leaf water potential of Populus euphratica on typical clear days of different mouths was similar. It was a V-curve and the minimums appear at 13:00 mostly. There was not obvious regularity of diurnal variation of leaf water potential on cloudy days and which had a narrow daily varial amplitude. The monthly variation increased firstly and then decreased. The monthly average value was -2.44 MPa. Trees with younger ages had higher leaf water potential. Leaves on the upper branches had lower water potential and vice versa. Water potentials of the oval leaves exceeded the lanceolate leaves as a whole. Multiple linear fitting equation between Ta, RH, VPD and Ψ was: Ψ=-0.171VPD-0.05Ta-0.01RH, R2=0.99; there were good fitting relationships between Ψ and Tr, Pn, the determination coefficients were 0.78 and 0.85. Lower soil water content corresponded to lower leaf water potential. The diurnal variation tendency in leaf water potential of Populus euphratica and Tamarix ramosissima was similar. However, the diurnal average value (-5.96 MPa) of the latter was much lower than the former’s(-2.58 MPa). Tamarix ramosissima had a wider daily varial amplitude (2.76 MPa) than Populus euphratica (1.33 MPa). |
| 中文关键词 | 液流速率 ; 林分耗水量 ; 叶水势 ; 胡杨 ; 荒漠河岸林 |
| 英文关键词 | sap flow velocity water consumption of forest stand leaf water potential Populus euphratica desert riparian forest |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 环境工程 |
| 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/2XILL650/287378 |
| 推荐引用方式 GB/T 7714 | 李小琴. 荒漠河岸胡杨液流与叶水势特性研究[D]. 中国科学院大学,2014. |
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