杨树人工林冠层光合辐射分布的研究

通过对集约经营与粗放经营杨树人工林冠层上部，下部太阳总辐射和光合有效辐射（ＰＡＲ）的实测数据进行分析，建立了其相互转换的关系方程；研究了ＰＡＲ的日、季变化特征；根据Ｂｅｅｒ－Ｌａｍｂｅｒｔ方程，结合林分生长季内的叶面积动态及林冠各层次的叶面积指数（ＬＡＩ），计算出生长季内各天的消光系数（Ｋ）及任一时刻冠层内不同深度的光分布，并对ＰＡＲ的透过率与林分消光系数Ｋ及累积叶面积指数之间的相互关系进行了研究

THE DISTRIBUTION OF PHOTOSYNTHETIC RADIATION IN THE CANOPY OF POPLAR PLANTATION

According to the data of total solar radiation and Photosynthetically Active Radiation(PAR) in intensive and extensive silviculture poplar plantation, the equations of transforming from total radiation to ground PAR were established. Combined with the leaf Area Index(LAI) and its vertical distribution in the canopy, the extinction coefficients(k) and vertical distribution of PAR in the two stands were calculated respectively. The daily and seasonal change of K and PAR transmittance were discussed also. The relationship between PAR transmittance and cumulative LAI within the canopy was established, the result showed it is a linear model. Compared the absorbtion of PAR in two stands, since intensive culture stands with higher leaf area in the different layers of canopy, so the interception of PAR in intensive culture stand is higher than that in the extensive culture stand, this resulted the higher productivity in the former.