Some biometeorological features of wheat field in the ecological conditions of oasis at the Heihe Region
黑河地区绿洲生态条件下麦田生物气象若干特征

We observed and analysed some characteristics of biometeorology over and within canopy in spring wheat field in the ecological conditions of oasis during HEIFE program.Water potential in SPAC appeared a well vertical profile and the profile showed an obvious diurnal variation.There were water potential jumps in the SPAC junction boundaries.Sequence of variation intensity for water potential in each part of the SPAC was atmosphere,plant and soil.It is shown that the water potential was influenced and controlled strongly by the process of plant water metabolism and up to meteorological factors.Atmosphere mixed well in day time in comparison with night time in near surface over the wheat field from the time space section of wind speed,ambient temperature and relative humidity.The structure of atmosphere was stable before sun raising.It revealed that the atmospheric features over wheat canopy in oasis were affected and controlled by hot and dry air from desert or Gobi.There were also ambient temperature,relative humidity vertical profiles within canopy as well as CO 2 concentration,PAR,leaf transpiration,photosynthesis,stomatal conductance and leaf surface temperature.The diurnal variations of profiles were drived mainly by the solar radiation,and in the same time,also were affected by the intensity of leaf water metabolism in different height leaf layer within canopy and soil status.The vertical profiles of ambient temperature and relative humidity within canopy appeared a quite different variation pattern in comparison with over canopy.