【摘要】 为揭示典型天气下阔叶树种的液流变化差异及其主要影响因素,以北京平原区的4种阔叶乔木为研究对象,利用热扩散插针法对树干液流进行连续观测,同时结合Meter全自动气象站同步观测的环境因子,分析树木蒸腾特征及其影响因素,结果显示:(1)在典型天气条件下,4种阔叶树种液流日变化特征均为晴天液流日变化呈单峰型曲线,阴天呈双峰型变化,雨天则呈多峰型趋势;液流启动时间为晴天和阴天(06:00)早于雨天(06:30)。(2)各环境因子中太阳辐射日变化与液流相似,且各环境因子间相互影响,尤其太阳辐射与温度间存在滞后效应。(3)各环境因子中,太阳辐射、温度、风速及水汽压亏缺(VPD)均与液流呈极显著正相关(P<0. 01),而空气相对湿度则与液流呈极显著负相关(P<0. 01);同步观测的环境因子日变化与液流日变化存在时滞效应。(4)主成分分析结果发现,大气温度和太阳辐射作为主要影响因子贡献率为74. 37%;水汽压亏缺贡献率为14. 33%。(5)各树种7月总耗水量为毛白杨(289. 23 kg)>刺槐(235. 04 kg)>国槐(151. 53 kg)>栾树(133. 80 kg),日耗水量大小顺序与月耗水量相同,且晴天高于阴雨天。研究结果可为北京市园林树种的生态水文过程和影响因素综合评定提供一定的科学依据。更多还原

【Abstract】 To illustrate the differences in characteristics of sap flow of broadleaved species and their main influences in typical weather condition,sap flow rates of four broadleaved tree species were continuously monitored through the thermal dissipation probes( TDP) in plain areas of Beijing,combining simultaneous observations of environmental factors via automatic weather station,to explore the transpiration patterns of tree species and influencing environmental factors. The results show that diurnal variations in sap flow rates of 4 broadleaved species presented single-peak curves in sunny days,bimodel curves in cloudy days and multi-peaks curves in rainy days. The sap flow began at 6: 00 a. m. in sunny and cloudy days which were earlier than that in rainy days( 06: 30 a.m.). The diurnal patterns of solar radiation were consistent with that in sap flow. There exist interactions among environmental factors. Particularly,there is a lag-effect in variations between solar radiation and temperature. Considering the influencing extent of environmental factors on sap flow,solar radiation,temperature,wind speed and water vapor pressure deficit( VPD) were significantly positively related with the sap flow rates of four tree species( P<0.01),whereas there were remarkable negative correlationships between relative air humidity and sap flow rates( P<0.01). Diurnal variations of environmental factors were not in synchrony with that of sap flow rates of tree species. Based on the principal component analysis,as the main influentors,air temperature and solar radiation were responsible for 74.37% on variations of sap flow of tree species,while water vapor pressure deficit contributing 14.33%. Total monthly water consumptions of four tree species in July were ranked as Populus tomentosa( 289. 23 kg) > Robinia pseudoacacia( 235.04 kg) >Sophora japonica( 151.53 kg) > Koelreuteria paniculata( 133.80 kg). The daily water consumption of above species had the same sequence with that of monthly water consumption mentioned above. The water consumptions of tree species in sunny days were observed higher than that in rainy days. The results of the study can provide a certain scientific basis for the comprehensive evaluation on ecological hydrological processes and determination on influencing factors of garden tree species in Beijing.更多还原