| 摘要: |
| 【目的】探究香榧（Torreya grandis var. merrillii Hu）树干液流与主导环境因子在不同季节的时滞效应及使用白昼数据与全天数据进行时滞效应分析的差异性，阐明树体水分状态变化对环境因素的响应特性。【方法】以生长于皖南地区的17年生香榧为研究对象，采用热扩散法测定树干液流密度，使用生态定位观测法获取观测期内的气温、空气相对湿度、光合有效辐射（PAR）数据，并依据气温、空气相对湿度计算饱和水汽压差（VPD）。基于2年的观测数据，利用方差分析及显著性检验、相关分析及错位对比法，分析香榧树干液流密度和主导环境因子VPD、PAR的季节变化特征，以及在1 d和0.5 h观测时间窗口下树干液流密度对VPD、PAR响应的时滞特性。【结果】VPD和PAR的季节变化均呈单峰变化趋势。春季和夏季的树干液流密度与秋季和冬季相比具有更好的集中趋势，且其树干液流密度均值与秋季和冬季间均存在显著差异（P≤0.05）。1 d时间窗口下的树干液流密度对VPD、PAR的响应不存在时滞效应。在0.5 h时间窗口下，使用全天数据进行时滞效应分析时，树干液流密度在春季、冬季对VPD响应的时滞分别为15 h（相关系数(r)=－0.142）和14 h（r=0.144），对PAR响应的时滞分别为12.5 h（r=-0.097）和12 h（r=0.124）；使用白昼数据进行时滞效应分析时，树干液流密度在春季、秋季、冬季对VPD响应的时滞分别为－7 h（r=－0.177）、－5 h（r=－0.272）和－14.5 h（r=0.206），在春季、冬季对PAR响应的时滞分别为14 h（r=－0.141）和－14.5 h（r=0.179）；其他情况下树干液流密度对VPD、PAR的响应不存在时滞。【结论】树干液流密度对主导环境因子VPD、PAR的响应存在－14.5～15 h的提前或滞后；仅使用白昼数据进行树干液流密度与主导环境因子的时滞效应分析，可以获得更好的响应性；进行树干液流与主导环境因子的时滞效应研究，应考虑季节因素对研究结果的影响。 |
| 关键词: 香榧 树干液流密度 时滞效应 饱和水汽压差 光合有效辐射 热扩散法 |
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| 基金项目:中央财政林业科技推广示范项目（175070050002）；安徽省教育厅一般项目（KJHS2021B01）；黄山学院人才项目（2020xkjq012） |
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| Time-lag of trunk sap flow of Torreya grandis var.merrillii Hu in response to dominant environmental factors |
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TIAN Yuan,DAI Huiyan,LIU Xuan,et al
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| Abstract: |
| 【Objective】The time-lag effect and its variability of Torreya grandis var.merrillii Hu trunk sap flow in response to dominant environmental factors in different seasons based on daytime data and all-day data were explored to clarify changes of tree water in response to environmental factors.【Method】The 17-year-old T. grandis in southern Anhui was selected and the trunk sap flow density was measured by the thermal diffusion method for 2 years.Air temperature,air relative humidity and photosynthetically active radiation（PAR）data were acquired by ecological positioning observation method.The vapor pressure deficit（VPD）was calculated based on air temperature and air relative humidity.The ANOVA,significance test,correlation analysis and mismatch comparison analysis were applied to analyze seasonal variation characteristics of the trunk sap flow density of T. grandis and dominant environmental factors of VPD and PAR.Then,the time-lag characteristics of sap flow density in response to VPD and PAR in observation time windows of 1 d and 0.5 h were analyzed.【Result】The seasonal variations of VPD and PAR showed a single peak trend.Compared with autumn and winter,the sap flow density in spring and summer was more concentrated.The sap flow density in spring and summer was significantly different from that in autumn and winter (P≤0.05).In the 1 d time window,there was no time lag of sap flow density in response to VPD and PAR.In the 0.5 h time window,all-day data showed that time-lag of trunk sap flow density in response to VPD in spring and winter was 15 h (correlation coefficient (r)=－0.142) and 14 h (r=0.144),and that to PAR was 12.5 h (r=－0.097) and 12 h (r=0.124).Daytime data showed that time-lag of trunk sap flow density was －7 h (r=－0.177),－5 h (r=－0.272) and －14.5 h (r=0.206) in response to VPD in spring,fall and winter,and 14 h(r=－0.141) and －14.5 h(r=0.179) in response to PAR in spring and winter.There was no time-lag of trunk sap flow density in response to VPD and PAR in other cases.【Conclusion】There was －14.5 h to 15 h time-lag of trunk sap flow density in response to the dominant environmental factors of VPD and PAR.Daytime data had better responsiveness in analyzing the time-lagged effects of trunk sap flow density.Seasonal factors should be considered for the study of time-lag effect of trunk sap flow in response to dominant environmental factors. |
| Key words: Torreya grandis var. merrillii Hu trunk sap flow density time-lag effect vapor pressure deficit photosynthetically active radiation thermal diffusion method |
