板栗密植园树冠结构特征与光能分布规律的研究

THE CHARACTERISTICS OF CANOPY STRUCTURE AND PATTERNS OF LIGHT DISTRIBUTION IN HIGH DENSITY PLANTING ORCHARD OF CHESTNUT

采用方格法和分层法对江苏省新沂市沐河果园４种不同密度（４ｍ×３ｍ、３ｍ×２．５ｍ、３ｍ×２ｍ、２ｍ×１．５ｍ）８年生板栗密植园的树冠结构特征和光能分布规律进行了研究。结果表明：随着密度的增大，树冠直径减小，绿叶层上移，叶幕厚度变薄，树冠体积减少；各层叶幕中的光能分布随着自然光照的变化而改变，其日平均透光率大小和光合有效辐射（ＰＡＲ）日变化范围均从叶幕外围向内膛而递减，树冠结构和叶面积指数（ＬＡＩ）对ＰＡＲ分布及利用效率具有决定性的影响。成龄板栗密植园高效光合生产的叶幕厚度宜在２．０ｍ以上，有效叶面积指数５～６，适宜密度为８３４～１３３４株／ｈｍ２。

Using gird system and layer methods, the characteristics of canopy structure and the patterns of light distribution in the 8 year old trees in four different high densities(4 m×3 m,3 m×2 5 m,3 m×2 m,3 m×1 5 m) orchards of chestnut( Castanea mollissima ) were studied in Xin Yi county, Jiangsu province. The results showed that the diameter of canopy reduced, the layer of green leave raised,the thickness of canopy decreased and the volume of canopy reduced with the density increased; The light distribution in the different layers of the canopy varied with the changes of the natural sunlight. The mean daily light transmissivity and the daily changes of the light intensity were reduced from the external to the internal part of the canopy. The light distribution in the canopy and the efficience of its utilization were obviously affected by the structure of canopy and the leaf area index(LAI). The best density that has high efficience light usage should be maintained with 834～1334 trees.gha -1 , with the thickness of canopy more than 2.0 m and an effective leaf area index of appoximately 5～6.