Solar radiation distribution within the canopy of Phragmites communis community in Panjin wetland

Based on micro-meteorological elements observation and biological observation in different layers within the canopy of Phragmites communis community,the relationship between solar radiation and leaf area index(LAI) within the canopy of Phragmites communis community in Panjin wetland during the growing season in 2005 was discussed.The results indicate that the vertical distribution of solar radiation shows S-curve at the early stage(May) and the late stage(September) of Phragmites communis growth,while it is exponential curve at the peak stage(June and July).Solar radiation transmittances in the canopy of different layers reduce with the increase of LAI.The extinction coefficient(k) changes seasonally,and it decreases from the sprouting stage to the mature stage.The minimum value of the extinction coefficient(k) is 0.436.