白榆冠层蒸腾及其对环境因子响应的边界线  

Characteristics and Boundary Line Analysis of Canopy Transpiration of Ulmus pumila to Environmental Driving Factors

作　　者：韩磊[1] 黄晓宇 韩永贵 高阳 展秀丽 Han Lei;Huang Xiaoyu;Han Yonggui;Zhan Xiuli(Ningxia University,Yinchuan 750021,P.R.China)

机构地区：[1]宁夏大学

出　　处：《东北林业大学学报》2019年第12期22-27,共6页Journal of Northeast Forestry University

基　　金：宁夏自然科学基金项目(AAC03043)

摘　　要：以宁夏河东沙区防护林树种白榆(Ulmus pumila)为研究对象,采用热扩散茎流计实时监测林木树干液流,分析不同天气条件下蒸腾耗水特性;为避免时滞产生的回环效应,采用边界线分析法研究白榆冠层蒸腾(Ec)对大气环境响应的最佳估计。结果表明:(1)白榆冠层蒸腾速率由大到小晴天、阴天、雨天,并在晴天条件下出现"午休"现象;日平均液流速率为晴天467.97 g·h-1、阴天320.08 g·h-1和雨天44.62 g·h-1,且夜间液流速率不为0。白榆日耗水量分别为(10.06±0.84)kg·d-1(晴天)、(8.02±0.48)kg·d-1(阴天)和(1.06±0.01)kg·d-1(雨天),其中夜间耗水量分别占全天耗水量的2.1%、3.0%和3.8%。(2)大气环境因子与白榆冠层蒸腾呈极显著相关关系(P<0.01),对Ec的影响从大到小依次为太阳辐射(RPA)、大气温度(Ta)、水汽压亏缺(DVP),分别可以解释41.1%、20.3%和4.4%的变量。(3)边界线分析得出,引起气孔调节的太阳辐射阈值为245 W·m-2;当DVP>1.35 kPa林木冠层蒸腾对水汽压饱和亏缺的响应敏感性降低,Ta>25.9℃和Ta<20.1℃时,成为诱导白榆气孔调节行为、限制冠层蒸腾的关键临界点。In order to quantify the diurnal variation of forest transpiration response to environmental factors in arid areas,Ulmus pumila,a typical tree species of protection forest growing in east sandy land of Yellow River in Ningxia was studied in a field trial.The Granier thermal dissipation probe technology was used in monitoring the sap flow continuously in the tree-growing season to clarify the characteristics of water consumption by transpiration under different weather conditions.To avoid the hysteresis loops effect caused by time lag,a boundary line analysis was used to describe the responses of canopy transpiration to meteorological factors,and the best estimation of canopy transpiration response to environmental factors was obtained.The daily canopy transpiration rate of U.pumila on sunny days>cloudy days>rainy days,and"the noon break of stem-flow velocity"phenomenon was found during 12 to 16 o’clock on the sunny days.Daily average sap flow velocity was 467.97 g·h-1 on sunny days,320.08 g·h-1 on cloudy days and 44.62 g·h-1 on rainy days separately.The diurnal change showed that the nighttime sap flow velocity was not zero.The daily water consumption of U.pumila was 10.06±0.84 kg·d-1 on sunny days,8.02±0.48 kg·d-1 on cloudy days and 1.06±0.01 kg·d-1 on rainy days,in which the water consumption at night accounted for 2.1%,3.0%and 3.8%of the whole day under different weather conditions,respectively.The variables as vapor pressure deficit(DVP),air temperature(Ta),and solar radiation(RPA)were significantly correlated with canopy transpiration of U.pumila(P<0.01).Based on the Pearson correlations and partial correlations analysis,the ranked factors from strong to weak correlated with the influence on Ec were RPA>Ta>DVP,explained 41.1%,20.3%and 4.4%of the total variation.Boundary line analysis indicated that the threshold of solar radiation causing stomatal regulation was 245 W·m-2,and the sensitivity of canopy transpiration responses to water vapor pressure saturation deficit decreased when DVP>1.35 kPa.I

关 键 词：白榆(Ulmus pumila) 树干液流 耗水量 冠层蒸腾 边界线分析 

分 类 号：S715.4[农业科学—林学]