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黄土丘陵区山杨树干液流动态分析
文献类型：学位论文
| 学位类别 | 硕士 |
| 答辩日期 | 2010 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 陕西 |
| 导师 | 徐学选 ; 杜 峰 |
| 关键词 | 山杨 液流 热扩散式探针 环境因子 |
| 其他题名 | Dynamic changes of Populus davidiana sap flow in hilly-gully region of Loess Plateau |
| 学位专业 | 生态学 |
| 中文摘要 | 本研究利用热扩散技术在黄土丘陵区延安市燕沟流域，对山杨（Populus davidiana）树干及相关枝条的液流流速进行了连续的测量（2009年4月14日—10月10日），并同步监测相应的环境因子（土壤水分、光合有效辐射强度、空气温度、空气相对湿度和风速），对于探明这山杨的蒸腾耗水规律，水土保持林区水分管理、林地水文效益分析等具有重要参考价值。本文着重分析了不同季节树干枝条液流的变化特征，及液流变化与环境因子的关系研究，取得了如下结论： （1）山杨树干液流流速变化特征 在整个监测阶段，无论是晴天还是阴天，山杨的树干液流均表现出明显的昼夜变化规律，呈现上升快、下降缓慢的单峰曲线。液流启动以后到达最大值之前液流流速会发生强烈的波动，形成许多由小峰组成的“高峰平台”，然后才开始下降，夜间仍有微弱的液流存在，没有明显的树干液流静止状态的界限。虽然，整个监测阶段液流变化都是呈单峰曲线，但不同季节峰型曲线亦有差异。 在春季，每日液流的启动时间为6:00—7:30，并于13:30—15:30达到最大值，然后迅速下降，18:00以后下降直到日出前后到达低谷。在夏季，每日液流的启动时间为5:00 - 7:00；但液流达到峰值的时间却有很大差异：6月1日—6月19日，液流达到峰值的时间为14:00 – 16:00；6月20日—7月7日，由于长期的干旱无雨，导致液流流速逐日下降，与此同时，液流流速达到峰值的时间也提前至9:00—11:00；7月8日—8月31日，液流达到峰值的时间为12:00—14:00。然后迅速下降，18:00以后下降直到日出前后到达低谷。在秋季，液流的启动时间和液流达到峰值的时间均逐渐的向后延迟，每日液流的启动时间为6:30—10:00，并于12:30—17:00达到最大值，然后迅速下降。 （2）山杨树干液流流速与土壤因子的变化关系 在春季，土壤水分能充分保证树木的蒸腾耗水。在夏季，液流流速的变化与土壤湿度变化趋势基本一致，6月—7月中旬，土壤湿度逐渐减小，液流流速也逐渐下降；7月中旬—8月中旬，由于降雨量的增加，土壤湿度增大，液流流速有所回升，保持在一个较大的水平。在秋季，土壤湿度增大，液流流速逐渐变小。在整个监测期，研究发现土壤温度并不是影响液流活动主要的因子。 （3）山杨树干液流流速与气象因子的变化关系 在春季，液流流速主要受空气温度、VPD的影响，在此阶段虽然土壤水分逐渐下降，但不足以影响液流。在晴天，树干上部枝条边材液流流速明显大于树干下部边材液流流速；在阴雨天，下部边材液流流速反而比上部液流流速大。另外，在干旱胁迫下，液流流速会明显下降，且峰值出现的时间都会提前。 在夏季，在降雨较少阶段，枝条液流主要受光合有效辐射强度、空气温度的影响；在雨水相对充足的阶段，树木上部枝条液流主要受空气温度与光合辐射强度的影响；树木下部枝条液流主要受空气温度与VPD。在晴天，树干上部枝条液流流速大于树干下部液流流速；而在阴雨天，不同的枝条边材液流流速无明显差异。在夏季，树干液流速率与气象因子的 Pearson 相关系数均小于春秋两季。 在秋季，液流流速主要受空气温度、VPD的影响，与春季的结论相同。在晴天，树干上部枝条边材液流流速大于树干下部边材液流流速；而在阴雨天下部液流流速仍小于上部液流流速。 |
| 英文摘要 | In this study, the thermal dissipation probe (TDP) was applied to measure the sap flow velocity of Populus davidiana in Yan’an City on the Loess Plateau of China from April 14 to May 22, 2009. Soil water content, photosynthetic active radiation (PAR), air temperature, relative air humidity, and wind speed were measured at the same time. Study the law of transpiration water consumption of those two forest types has important reference value to the water management of soil and water conservation forests as well as to the analysis of forest hydrologic effect. After the study of dynamic changes of Populus davidiana sap flow velocity，and the relationship between sap flow and the environmental factors, major conclusions got were as follows: 1. Sap flow velocity dynamics of Populus davidiana Diurnal variation of sap flow velocity displayed unimodal curve with fast-rising and slow-declining trends in the whole growth season. The sap flow velocity didn’t stop after reaching its peak, but there were minor fluctuations, a number of small peaks formed a "peak platform", and then began to decline. The sap flow also exists in night though it is small. The unimodal curve is different from others in different seasons. In spring, the sap flow started to increase at 6:00—7:30, reached the peak value at 13:30—15:30, and descend at 18:00. In summer, the sap flow started to increase at 5:00—7:00, but the time of sap flow velocity reached the peak value has a greatly differences. From June 1 to June 19, the sap flow velocity reached the peak value at 14:00—16:00. From June 20 to July 7, the sap flow reached the peak value at 9:00—11:00 because the drought. From July 8 to August 31, the sap flow reached the peak value at 12:00—14:00. In autumn, the time of sap flow started to increase and reached the peak value both delay to 6:30—10:00 and 12:30—17:00. 2. The relationship between sap flow velocity and soil factors Soil water content was gradually declined in spring, but its’ influence on the sap flow was not significant. The sap flow velocity declining goes with the soil water content in June and middle of July. Because there was plentiful rainfall, the soil water content was recruited quickly. At the same time, the sap flow velocity was also increasing gradually and maintained a high-speed level. In autumn, the soil water content was recruited quickly because of the rainfall. The soil water content was so excessive that the sap flow velocity was restrained. In this study we conclude that the soil temperature has nothing to do with the sap flow velocity. 3. The relationship between sap flow velocity and soil factors In spring, the sap flow velocity was significantly correlated with air temperature and water vapor pressure deficit (VPD), and the correlated coefficients were highly significant at 1% safety. Soil water content was gradually declined in this period, but its’ influence on the sap flow velocity was not significant. The peak of sap flow velocity in the upper trunk was higher than that in the lower trunk apparently in fine days, while it was lower in clouded and rainy days. The sap flow velocity peak became smaller day-by-day as the drought became seriously in both upper and lower trunks, and the appearing time of upper trunk’s sap flow velocity peak was getting earlier while that of lower trunk’s sap flow velocity peak was getting later. In summer, the sap flow velocity was significantly correlated with photosynthetic active radiation (PAR) and air temperature in fine days, and the peak of sap flow velocity in the upper trunk was higher than that in the lower trunk apparently. But in clouded and rainy days, the sap flow velocity of the upper trunk was significantly correlated with photosynthetic active radiation (PAR) and air temperature, and the sap flow velocity of the lower trunk was significantly correlated with water vapor pressure deficit (VPD). The peak of sap flow velocity in the upper trunk and the lower trunk was no apparently change. Pearson correlation coefficient of sap flow velocity to climatic factors in summer is less than that in spring and autumn. In autumn, as same as in spring the sap flow velocity was significantly correlated with air temperature and water vapor pressure deficit (VPD). The peak of sap flow velocity in the upper trunk was higher than that in the lower trunk apparently both in fine days and clouded days. |
| 公开日期 | 2011-09-02 |
| 分类号 | S718.43 |
| 源URL | [http://ir.iswc.ac.cn/handle/361005/4152]  |
| 专题 | 水土保持研究所_水保所知识产出(1956-2013) |
| 推荐引用方式 GB/T 7714 | . 黄土丘陵区山杨树干液流动态分析[D]. 陕西. 中国科学院研究生院. 2010. |
入库方式： OAI收割
来源：水土保持研究所
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