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塔里木河下游河岸胡杨耗水模型研究
赵天宇
学位类型硕士
导师苏里坦
2015
学位授予单位中国科学院大学
学位授予地点北京
学位专业自然地理学
关键词塔里木河下游 胡杨 液流速率 环境因子
摘要在生态系统中,森林是一个巨大的水分利用系统,它通过降水量,储存水分,减少地表径流,提高水分的利用。胡杨是干旱区的重要特种树木,根系发达,主要依靠地下水生存。在降水量偏小,气候极端干旱的西北地区,水资源紧缺,水分蒸发量快。在绿化造林和植被恢复过程中,通过胡杨树干液流量来估算胡杨林的耗水量,从而控制水分浪费,可以有效地利用塔里木河水资源。利用热扩散技术测定树木耗水量是当前的研究热点。 本研究以塔里木河下游的三种不同树龄的胡杨作为研究对象,从1月到12月连续测定胡杨树干液流量,以液流量日变化、月变化和季节变化来分析液流量变化规律并对液流量和环境因子进行同步监测。目的是研究胡杨树干液流量的日液流量变化,月液流量变化和季节液流量变化规律,找出影响胡杨树干液流量的最大影响因子,建立液流量与环境因子之间的回归方程,为塔里木河下游地区的胡杨输水情况和水资源的合理利用提供理论基础和参考依据。研究结果表明: 1) 三种不同树龄胡杨树干液流量有相似的变化规律,但是在液流量上存在一些差异。植物液流速率不仅受到自身的生理影响,而且还受到周围环境的影响; 2) 胡杨树干液流量的日变化规律存在明显的昼夜变化。晴天液流启动早、停止晚、高峰持续时间长;阴天则启动晚、停止早、高峰持续时间短,液流速率小,夜间液流速率依靠根压来进行微弱的活动,并且所占比例随着气候的变化也大有不同,夏季胡杨树干液流速率由于大气温度和太阳净辐射量的增加,占全年液流速率的比例远大于春季、秋季以及冬季; 3) 相关性分析表明,胡杨树干液流速率与气象因子存在着良好的相关性,在一定范围内,与太阳净辐射、大气温度呈显著性正相关,与相对湿度呈负相关,与风速的相关性较差;至于土壤因素,虽然相关性较小,但仍然起着重要的作用;胡杨日液流量与地下水位和胡杨胸茎横截面积也具有极高的相关性,并与地下水位呈显著性负相关,与横截面积呈显著性正相关。 4) 三个回归模型均表现出较好的模拟效果,其中非线性回归模型的模拟精度最高,三年拟合系数分别为0.5326、0.6760和0.6949,具有使用简便、影响因子易测定、一定精度等优点,能够更好刻画植被腾发量的复杂的非线性特性,为干旱区自然植被耗水量估算、模拟和生态需水量计算提供了新的思路和方法。
其他摘要The forest is a huge water consuming system which stores water through precipita-tion, reduces surface runoff, and increase water use efficiency. Populus euphratica is one of the important trees in arid areas, which has large root system, and mainly relies on groundwater. Water resources are scarce, and water evaporation is large in extremely arid northwestern region. In the process of afforestation and vegetation restoration, estimating water consumption of P. euphratica tree by trunk sap flow is important for saving water and effectively using water resources in the Tarim River. Thermal diffusion technology was used to estimate water use of trees in current researches. In this study, three different stages P.euphratica in the lower reaches of the Tarim River were chosen, the daily, monthly and seasonal sap flows were measured and ana-lyzed from January to December through continuously observation. The aim of the study is to find out the main factors affecting sap flow variations and to establish the regression equation between sap flow rate and environmental factors. The results will provide theo-retical basis and references for rational use of water resources for P.euphratica in the lower reaches of the Tarim River: The results showed that: 1) There are similar trend in P.euphratica tree trunk sap in three different ages, but there are some differences in the amounts of sap flow. Plant sap flow rate not only af-fected by their physiological conditions, but also by its surrounding environments. 2) The amount of P.euphratica tree trunk sap flow showed obvious diurnal variation. Compared with the cloudy days, the sap flow rate in the sunny days started earli-er,stopped later and kept much longer during the top period. In the night, sap flow kept moving all the time, and the proportion of sap flow rate in the evening is different in dif-ferent season. For the increases of air temperature and solar net radiation, the proportion of sap flow is much bigger than in other seasons; 3) There is a significant correlation between the sap flow rate and meteorological factors. To some extent, the sap flow rate was positively correlated with solar radiation and air temperature, negatively correlated with relative humidity and less correlated with wind speed; Soil factors also played an important role in the sap flow rage although there is less correlation. The correlation between underground water depth, cross sectional area and daily sap flow was significant, which was positively correlated with cross sectional area and negatively correlated with underground water depth; 4) Results showed that three regression models showed better simulating effect. sim-ulation accuracy of nonlinear regression model is higher than those of other two models. The coefficients of correlation between observed and simulated transpiration of P.euphratica were 0.5306, 0.6760 and 0.6949, respectively. The model is easy to use and measure and has high precision, which provides an effective and feasible way for the evaluation of natural vegetation evapotranspiration and the calculation of ecological wa-ter requirements in arid region.
学科领域自然地理学
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14682
专题研究系统_荒漠环境研究室
作者单位中科院新疆生态与地理研究所
推荐引用方式
GB/T 7714
赵天宇. 塔里木河下游河岸胡杨耗水模型研究[D]. 北京. 中国科学院大学,2015.
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