油蒿(Artemisia ordosica)茎流动态及其环境控制因子

Temporal patterns and environmental controls of sap flow in Artemisia ordosica

于2012年7—10月利用Flow32-1K(Dynamax,USA)包裹式茎流仪对宁夏盐池典型沙地的油蒿(Artemisia ordosica)茎流进行连续监测,同时观测环境因子。结果表明:油蒿茎流速率日变化动态受天气影响;晴天茎流速率峰值为107.81 g·cm-2·h-1,阴天茎流速率峰值为79.40 g·cm-2·h-1,降雨时茎流峰值是4.34 g·cm-2·h-1;油蒿茎流速率呈现明显的季节变化,7月最大,10月最小;在干旱期土壤水分为油蒿茎流速率的决定因素,其中30 cm深度土壤含水量的解释能力最强;在非水分胁迫期油蒿茎流速率与气象因子相关性最强,对油蒿茎流速率影响的大小顺序为饱和水汽压差>平均空气温度>太阳辐射>相对湿度。

Sap flow in Artemisia ordosica, together with environmental variables, were continuously measured in situ from July to October 2012. Results showed that weather conditions exerted a strong control over the diurnal pattern of sap flow. The daily maximum sap flow rates were 107.81, 79.40, and 4.34 g·cm-2·h-1 on sunny, cloudy and rainy days, respectively. Sap flow showed pronounced seasonal variations, with the maximum occurring in July and the minimum in October. During drought periods, daily sap flow rate increased with soil water content, with that measured at 30 cm depth having the highest explanatory power. Under higher soil water conditions, daily sap flow rate showed a strong correlation with micrometeorological factors. Based on correlation analyses, these factors were ranked as follows in terms of the magnitude of their effects on sap flow： vapor pressure deficit 〉 solar radiation 〉 average air temperature 〉 relative humidity.